Origins of Recombinant Toxins: History
View Latest Version
Please note this is an old version of this entry, which may differ significantly from the current revision.
Subjects: Toxicology
Contributor:
Elena Efremenko
,
Aysel Aslanli
,
Ilya Lyagin

Toxins produced by various living organisms (bacteria, yeast, scorpions, snakes, spiders and other living organisms) are the main pathogenic factors causing severe diseases and poisoning of humans and animals. To date, recombinant forms of these toxins are widely used as antimicrobial agents, anticancer drugs, vaccines, etc. Various modifications, which in this case can be introduced into such recombinant proteins, can lead to a weakening of the toxic potency of the resulting toxins or, conversely, increase their toxicity. Thus, it is important to publicly discuss the situations and monitor the emergence of such developments.

  • protein
  • recombinant toxin
  • antivenom
  • vaccines
  • killer toxins
  • enzymatic antidots

1. Introduction

To date, recombinant toxins from various biological sources (bacteria, yeast, scorpions, snakes, spiders and other living organisms) are widely used as: (i) antimicrobial agents for medical purposes, as well as antimicrobial additives for the food and biotechnological industries, (ii) groundwork for the creation of drugs with anticancer activity and the treatment of neurodegenerative diseases and (iii) the basis to develop vaccines, etc. Multiple works have been performed to study the mechanisms of action of genetically modified toxins and their applications [1][2][3][4][5][6] (Figure 1).
Ijms 24 04630 g001 550
Figure 1. Various applications of recombinant toxins.
The protein/polypeptide nature of most of these natural toxins allows them to obtain their recombinant forms. The potential for developing these biomolecules in high enough quantities is the basis for further advancements in developing vaccines and drugs with reduced cost and their widespread use, on the one hand. On the other hand, the production of recombinant toxins avoids the need to work directly with the natural sources of these biomolecules (animals and microbial pathogens). Obtaining genetic constructs encoding the synthesis of recombinant toxins expands the possibilities of their synthesis in special modified forms. Like many recombinant proteins, recombinant toxins can be obtained in high yields using different expression systems, including extracellular secretion, and further isolated and finely purified using affine carriers [7][8].

2. Spectrum of Recombinant Toxins and Their Origins

Most of proteinaceous toxins well-studied to date are produced by various bacteria. However, toxins that are found in yeast, snake, scorpion and spider venoms and other living organisms are also actively studied by various scientific groups today. Recombinant toxins obtained from various origins and purposes of their obtaining are presented in Table 1 [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64].
Table 1. Recombinant toxins from various origins and the purposes of their obtaining.
Protein Origin Reference
Production
BoNT Bacteria Clostridium botulinum [9]
Killer toxins K1, K28, K1L Yeast Saccharomyces paradoxus [10][11][12]
Killer toxin Kpkt Yeast Tetrapisispora phaffii [13][14]
ppa1, Tppa2, Tce3, Cbi1 Scorpions of the genus Tityus and Centruroides [15]
β/δ agatoxin-1 Spider Agelena orientalis [16]
Purotoxin-1 Spiders of the genus Geolycosa sp. [17]
Azemiopsin, Three-Finger Toxins Viper Azemipos feae [18][19]
MdumPLA2 Coral snake Micrurus dumerilii [20]
APHC3, HCRG21 Sea anemone Heteractis crispa [21][22]
Toxicity assays
C3bot, C3botE174Q, C2IIa Bacteria Clostridium botulinum [23][24][25]
LeTx Bacteria Bacillus anthracis [26]
HlyII Bacteria Bacillus cereus [27][28]
Cry1Ia Bacteria Bacillus thuringiensis [29]
BFT Bacteria Bacterioides fragilis [30]
EGFP-SbB, translocation domain
(TD) of the diphtheria toxin		 Bacteria Corynebacterium diphtheriae [31][32]
In1B Bacteria Listeria monocytogenes [33]
LcrV Bacteria Yersinia pestis [34]
AtaT2 Bacteria Escherichia coli [35]
Killer toxin Kpkt Yeast Tetrapisispora phaffii [36]
MeICT, KTx Scorpion Mesobuthus eupeus [37][38][39]
Tbo-IT2 Spider Tibellus oblongus [40]
α-conotoxins, α-cobratoxin Marine snail and snake venom [41]
Three-Finger Toxins Viper Azemipos feae [42]
α-neurotoxins Cobra Naja melanoleuca [43]
Hct-S3 Sea anemone Heteractis crispa [44]
Immunology assays
BoNT Bacteria Clostridium botulinum [45]
Beta and epsilon toxins Bacteria Clostridium perfringens [46][47]
Cholera toxin subunit B (CTB) Bacteria Vibrio cholerae [48]
Ancrod, batroxobin, RVV-V Snakes Calloselasma rhodostoma, Bothrops atrox, Daboia russelii [49][50]
Modifications
BoNT/B-MY, C2IN-C3lim Bacteria Clostridium botulinum [51][52]
DT389-YP7, s-DAB-IL-2(V6A), DT2219 Bacteria Corynebacterium diphtheriae [53][54][55]
rPA83m + plant virus spherical particles (SPs) Bacteria Bacillus anthracis [56][57][58]
SElP + Zn Bacteria Staphylococcus aureus [59]
PE38 + AgNP Bacteria Pseudomonas aeruginosa [60]
CTB-KDEL Bacteria Vibrio cholerae [61]
GFP-L2-AgTx2 Scorpions Mesobuthus eupeus and Orthochirus scrobiculosus [62]
LgRec1ALP1 Spiders of the genus Loxosceles [63]
Ms 9a-1 fragments and homologues Sea anemone Metridium senile [64]

2.1. Bacterial Recombinant Toxins

Bacterial cells are capable of synthesizing endo- and exotoxins. Endotoxins, as a rule, are cell-bound lipopolysaccharides that are released after cell destruction, while exotoxins are protein toxins that are synthesized inside cells and released into the environment. Thus, the recombinant forms of these exotoxins are discussed next (Table 1).
Botulinum neurotoxin (BoNT) and tetanus toxin (TeNT) produced by cells of the Clostridium botulinum and C. tetani, respectively, are among the most dangerous and therefore the most well-studied bacterial toxins. Botulism and tetanus diseases caused by these toxins are among the most severe neurological diseases that cause flaccid paralysis and spastic paralysis, respectively. In addition, BoNT is widely used to treat a number of diseases. Consequently, recombinant forms of these toxins have been actively created and researched for many years with the aim of both developing effective antidotes and obtaining drugs based on them.
A double-blind, placebo-controlled study evaluated the safety, tolerability and pharmacodynamics (PD) of the recombinant botulinum toxin serotype E (rBoNT-E) compared with commercial botulinum toxin type A (ABO, Dysport ®) [9]. All doses of the recombinant toxin were well tolerated, and rBoNT-E had a faster onset of action, a greater peak effect and a shorter duration of effect at the highest tested doses compared with ABO.
To solve an opposite task and neutralize BoNT and other toxins, various antibodies are usually used. Special interest is afforded to single-domain camel antibodies (sdAb, VHH or nanobody) possessing unique structure and characteristics and their chimeras with usual human immunoglobulins. As a result, such immunotherapeutic agents could have up to 1000 times increased protective activity against C. botulinum and prolonged circulation in blood [45].
Different subtypes of BoNT have a varying toxicity, and BoNT/A is more potent toward the human neuroblastoma cell line as compared to BoNT/B [51]. At the same time, genetic modification of the latter to BoNT/BY resulted in improved affinity for human synaptotagmin and BoNT/B receptor, as well as increased toxicity toward this cell line.
C3 protein toxin from C. botulinum (C3bot) cells is a mono-ADP-ribosyltransferase that selectively intoxicates macrophages, osteoclasts and dendritic cells by cytosolic modification of Rho GTPases (Rho-A, Rho-B and Rho-C). Thus, C3bot and, even better, its nontoxic variant C3botE174Q have been proven as perspective transporters for selective delivery of small molecules, peptides and proteins to the cytosol of macrophages and other cells [23][24].
Proteolytically activated separate binding/transport subunit C2IIa of C2 toxin from C. botulinum has been found [25] to be a specific inhibitor of chemotaxis of polymorphonuclear neutrophils (PMN), allowing selective suppression of excessive and harmful PMN recruitment to organs as a result of trauma. The enzymatically inactive N-terminal part of the C. botulinum C2 toxin (C2IN) when fused to Rho-inhibiting C3 toxin from C. limosum (C3lim) significantly improves the toxic action of the latter [52]. In a clinically significant mouse model, the in vivo introduction of C2IN-C3lim into the lungs after a blunt chest injury prevented injury-induced recruitment of monocytes into the lungs. Thus, such combinatorial fusion chimeras can be of practical interest due to great variability of available toxin modules.
Until now, vaccination has been the best way to combat diseases associated with many bacterial strains, including C. perfringens cells and α-, β- and ε-toxins of the bacteria. However, commercially available vaccines are based on inactivated toxins and have many manufacturing disadvantages that can be overcome using recombinant antigens. Recombinant α-, β- and ε-toxins were synthesized in E. coli cells to create a trivalent vaccine and evaluated on rabbits, cattle, sheep and goats. The levels of produced antibodies in all animals exceeded the minimum values recommended by international protocols [46][47], thus proving the viability of the approach. Even more, nonvirulent species of the same bacteria can be modified to bear a specific toxin or its part and safely modulate strong immune response, e.g., Vibrio cholerae cells expressing the β-subunit of cholera toxin (CTB) [48].
Another major group of proteinaceous toxins is produced by the members of the genus Bacillus. Bacillus cereus cells causing foodborne diseases secrete various pore-forming pathogenicity factors, including Hemolysin II (HlyII). As above mentioned, it can be specifically neutralized by antibodies [27], thus preventing mortality in vivo [28].
B. anthracis cells cause one of the most dangerous infectious diseases, Anthrax. The use of the Anthrax protective antigen (PA) is considered the most promising approach to the development of an Anthrax vaccine. However, the instability of the recombinant PA complicates the production of stable recombinant vaccines. Thus, a number of modification methods have been applied in recent years to design a stable recombinant Anthrax PA. For example, proteolytic-sensitive sites simultaneously with deamidation-prone amino acids can be genetically modified [56][57]. Alternatively, additional stabilizers, e.g., spherical particles (SPs) of tobacco mosaic virus, can be added [58]. Joint application of both methods gives even better results in terms of stability, immunogenicity and protectiveness of the final product, including in vivo tests with a fully virulent B. anthracis strain.
B. thuringiensis cells produce δ-endotoxins (Cry), which are toxic to a wide variety of insect pests and currently used widely in agriculture. Insertion of the gene encoding Cry1Ia toxin into a bacterial strain inhibiting fungal growth results in combined fungistatic and insecticidal activity as well as ability to induce plant resistance [29].
A lot of bacterial toxins in their structures contain metal ions performing various purposes. First of all, metal ions can be located in the active sites of metalloproteases such as BFT toxin from B. fragilis leading to damage and necrosis of the intestinal epithelium [30]. In addition, such metals can contribute to toxin structural stabilization and even promote recognition of the target receptor like in the case of staphylococcal enterotoxin-like protein P (SElP) from Staphylococcus aureus binding to major histocompatibility complex class II (MHCII) [59]. It should be noted that some virulence factors secreted by bacteria may be toxic to the microorganisms themselves. To prevent collateral damage and to additionally protect active components, they can be secreted in nanovesicles, which are able to be modeled in silico [30].
The diphtheria toxin (DT) from Corynebacterium diphtheriae kills mammalian cells by inactivating the elongation factor EF-2. The translocation domain in DT plays a critical role in allowing the catalytic domain to pass to the cytosol from endosomal compartments and can be used as a functional vector for active transport of protein drugs [31].
Some mammalian species are resistant to DT. The DT receptor, proHB-EGF, in resistant and sensitive species differs by amino acid sequence and therefore by secondary structure; however, there is no consensual opinion on how the difference in the structure of primary receptors changes the process of internalization of DT by resistant cells compared to sensitive ones. According to some publications [32], there can be even very little difference of binding constants of DT subunit B (which includes receptor-binding and translocation domains) to resistant and sensitive cells, while there was huge difference of intracellular concentrations of toxin within model cells. It means that multiple mechanisms of resistance to DT may exist in mammalian cells.
Several approved drugs, e.g., denileukin diftitox, which is fusion of DT with interleukin-2, are commercially available and actively used to date. However, research to improve their efficiency, producibility and safety as well as to obtain new therapeutics with DT are constantly continued [54][55].
Listeria monocytogenes cells apply internalins InlA and InlB to attach and penetrate into mammalian cells. Curiously, hepatocyte growth factor receptors (HGFR) together with other multiple variants are also affected by InlB [33]. This is important since HGF/HGFR play crucial role in liver restoration after its acute toxic damage. Thus, truncated bacterial InlB was implemented as a functional analogue of HGF to obtain novel drugs with hepatoprotective activity.
Bacterial toxins can interact not only with receptors themselves but with complexes of receptor and signal molecules. One of such examples is LcrV from Yersinia pestis [34]. It is a strong virulence factor having multiple functionalities, one of which is specific activation of human receptor-bound interferon-γ (hIFN-γ), which resulted in immune cell death via apoptosis. It became possible only after hIFN-γ binding to receptor and presentation of its 138GRRA141 site, which specifically interacts with 32LEEL35 and/or 203DEEI206 sites of LcrV. Thus, inactivation of these sites by specific antibodies completely prevents any harmful effects of LcrV.
Protein biosynthesis can be targeted by bacterial toxins, as well. For example, bacteria can utilize multiple enzymes from Gcn5-related N-acetyltransferase (GNAT) superfamily to acetylate and thus inactivate specific aminoacyl tRNAs, including transporters of Met, Ile, Gly, etc. [35].

2.2. Yeast Recombinant Toxins

Killer yeasts are able to produce proteins named “killer toxins” that are often glycosylated and bind to specific receptors on the surface of the sensitive microorganism, which is then destroyed by a target-specific mechanism of action (Table 1). They are widespread among yeasts and attract a lot of attention of researchers. To date, more than 100 types of killer yeasts have been described [65]. The most well-characterized killer toxins in terms of their genetic determinants, biochemical characteristics, molecular targets on sensitive cells and mechanisms of their destruction are toxins K1, K2 and K28 from Saccharomyces cerevisiae; zymocin from Kluyveromyces lactis; PMKT and PMKT2 from Pichia membranifaciens; PaKT from Wickerhamomyces anomalus; HM-1 from Cyberlindnera mrakii and Kpkt from Tetrapisispora phaffii. Due to their properties and spectrum of action, which is aimed at pathogenic microorganisms, recombinant killer toxins are being actively investigated in order to develop therapeutic agents based on them. However, the lack of research on their effects on humans and animals limits their use in the food and feed industry. Another drawback is that additional information about the mechanisms underlying the formation of killer toxins in yeast is required. Without solving these issues, it is not possible to successfully implement killer toxins in practice [65][66].
A study of S. paradoxus revealed a new K1-like toxin (K1L) being active against sensitive competing yeast cells [10]. It is encoded by double-stranded RNA (dsRNA) and satellite dsRNA, which may also be of virus origin. Its homologues have been identified in other six yeast species not belonging to Saccharomyces and are likely to be acquired by horizontal gene transfer via dsRNA and/or DNA with subsequent diversification of their structure and toxicity profile.
Genetic fusion of toxins with fluorescent proteins allowed researchers to study the binding of the toxin to the cell envelope of affected yeast [11]. However, intracellular translocation of labeled recombinant toxin K28 was not observed then, in spite of the presence of toxicity. It means there are gaps in our understanding of the true mechanism of killer toxin action and transport even among best-investigated ones. Further research is required to visualize intracellular transfer of toxins using high-resolution imaging techniques of individual molecules.
Killer toxin K1 is secreted by S. cerevisiae strains in a heterodimeric form. After binding to the primary receptor (β-1,6 glucans) in the cell wall, K1 is transported to the plasma membrane and is initially supposed to interact with its secondary receptor Kre1p, which ultimately leads to an ionophoric disruption of the membrane function. However, expression of recombinant K1α in resistant yeasts lacking Kre1p resulted in profound toxic effect [12], thus excluding role of the receptor. At the same time, co-expression of toxin precursor(s) in sensitive cells eliminated any negative effects. Thus, resistance to killer toxins is a part of adaptive (acquired) immune system.
Some killer toxins, e.g., Kpkt from T. phaffii (formerly Kluyveromyces phaffii), have antimicrobial activity not only on yeast but also on bacteria [13]. Interestingly, activity of Kpkt was not detected toward all tested mycelial fungi. Meanwhile, Kpkt has a β-1,3-glucanase activity [14][36] and thus can be combined, for example, with chitinases to synergistically improve their antifungal effects. At concentrations effective again yeasts, recombinant Kpkt has no effect on immortalized human epidermal keratinocyte cell line HaCaT [36]. That makes it promising for further investigations.

2.3. Recombinant Toxins of Various Animals

Venoms of snakes, scorpions and spiders are used by animals as their own defensive and offensive means by immobilizing victim and blocking the functional activity of their cardiovascular, respiratory and/or nervous systems. Proteinaceous toxins are the main components of these systems and modulate important ion channels and receptors after introduction into the body. Today, powerful databases of poisons and protein toxins with improved properties have been assembled already for more selective action, resistance to the effects of proteases, less immunogenicity and improved characteristics, in terms of pharmacokinetic properties. These characteristics can be improved by genetic modification of amino acid sequences, addition of disulfide and ion bridges, etc. After all, animal venom toxins are of great interest for applications in medicine as a basis for drug development [5] (Table 1).
The β/δ agatoxin-1 of the spider Agelena orientalis was obtained in recombinant form in the entomopathogenic fungus Lecanicillium muscarium with a special secretory signal peptide [16]. Further toxin was fused with eGFP to simplify the screening procedure. Unfortunately, toxic activity of the fusion protein was not investigated in the work.
Another fusion protein of GFP with agitoxin-2 from scorpion Leiurus quinquestriatus hebraeus was more useful [62]. That allowed researchers to visualize the binding of toxins to their receptor as well as to determine dissociation constants of various toxins competing for the same Kv1.3 channel.
Purotoxin-1 (PT1) from the venom of the Central Asian spider Geolycosa sp. selectively inhibits the purinergic receptor P2X3 and is a potent analgetic. It can be produced in pilot scale as self-cleavable fusion protein with mini-intein DnaB [17]. However, its purification is multistage and labor-intensive with modest yield at the end.
Interestingly, Tbo-IT2 toxin was identified in the spider Tibellus oblongus by cDNA analysis of the transcriptome of its venom glands [40]. Its amino acid sequence has a 41% identity match with the closest protein toxin, while its spatial structure folds into a well-known inhibitory cysteine knot (ICK). The first main difference is the formation of five disulfide bonds instead of the typical three that should result in extreme stability of the toxin. The second and the most puzzling difference is that Tbo-IT2 did not have inhibitory activity on the tested panel of available ion channels and neuroreceptors, while it is still toxic to the housefly, Musca domestica. Further research may elucidate the target(s) of the Tbo-IT2.
Another attempt to apply mini-intein DnaB was a little bit more successful [21], although the target toxin, APHC3 from the anemone H. crispa, which has analgesic activity, was produced in inclusion bodies and multistage purification was still required.
Fusion with His-tag and Smt3-leader peptide was shown to be a much more efficient method [22]. The resulting inhibitor of the TRPV1 ion channel (HCRG21 peptide from the sea anemone H. magnifica) was easier to purify and after cleavage was obtained at comparable yield to APHC3.
As stated previously with bacterial toxins, antibodies are used almost exclusively in antivenoms [20]. Combining several recombinant toxins in simple mixture [15][49] or even in fusion protein [63] often leads to improved efficiency of antivenoms, including comparing to commercial ones. Furthermore, it was found that rationally selected toxin-specific single-stranded DNA aptamers can exhibit broad cross-reactivity in vitro and ex vivo against isoforms of toxins found in various snake venoms [50].
Computer modeling provides powerful tools to thoroughly solve even complicated issues. For example, interaction of proteinaceous toxins KTx from scorpion M. eupeus with potassium channels (KV) was simulated and explained, followed by modulation of their activity using genetic modification [38][39]. In other work [43], authors have investigated binding of TFTs with novel receptors. Secondary structures of multiple actinoporins Hct from the sea anemone Heteractis crispa were generated [67], followed by analysis and successful structure–activity hypothesis testing.
Venoms contain a large number of biologically active compounds with diverse activities. Shorter peptides, e.g., azemiopsin acting on neuroreceptors [18] and bradykinin-potentiating peptides (i.e., affecting blood pressure) [19], could be prepared by a solid phase synthesis using a general Fmoc-method, while larger polypeptides are the most rational to produce using common expression systems [42][43].
A modulatory effect of some proteinaceous toxins on neuroreceptors is worth mentioning. Well-known three-finger toxins (TFTs) and their analogues [42][43] as well as azemiopsin bind mostly nicotinic acetylcholine receptors (nAChRs), but γ-aminobutyric acid receptors (GABARs) can also be affected [43].
Pore-forming toxins, e.g., Hct from the sea anemone H. crispa [44], have a wide nonspecific action and are almost equally cytotoxic to normal and malignant cells. However, fusing them with targeting partners, such as site-specific ligands, toxins or antibodies, could result in new drug platform development.
Recombinant toxins can be easily genetically modified and truncated to help researchers investigate their toxic action in a more detailed way. For example, peptide Ms 9a-1 from sea anemone Metridium senile causes significant analgesic and anti-inflammatory effects by desensitization of TRPA1-expressing sensory neurons, and it was thought to be a positive modulator of TRPA1 channel. However, truncation of its unordered domains on the N- or C-terminus resulted in complete loss of analgesic and anti-inflammatory activities in vivo [64]. Thus, another target receptor(s) is likely present in neurons.

2.4. Recombinant Prions

Prions (Pr) are infectious agents that cause devastating and incurable disorders known as transmissible spongiform encephalopathies (TSE). With the advent of innovative technologies, such as protein misfolding cyclic amplification (PMCA) and real-time quaking-induced conversion (RT-QuIC), in vitro amplification of prions has become possible. There is evidence suggesting that prion complexes can acquire high-order assemblies in vivo, which may look structurally ordered. However, the biophysical nature of these structures and their role in amyloid biology are still unclear. Despite the fact that the amyloid collected in vitro has some biochemical similarities with the ex vivo amyloid of the same protein, it often does not reproduce the biological activity of the latter. For example, preparations of prion protein (PrP), which are resistant to proteinase K and obtained exclusively from one recombinant PrP (rPrP), may not have any detectable infectious activity both in cell cultures and in animal bioassays. However, the proteinase K-resistant PrP obtained from rPrP is infectious if it is placed in the homogenate of a diseased brain ex vivo using the PMCA assay [68].
To study the rPrP, mechanisms of the development of toxicity and pathogenicity of prion diseases as well as their role in the development of pathologies of the nervous system is an important task of the world scientific community (Table 2, [69][70][71][72][73][74][75]).
Table 2. Recombinant prion proteins and purposes of their biosynthesis and use.
Recombinant Protein Purpose of Biosynthesis and Use Reference
rPrP from a baculovirus-insect cell expression system (Bac-rPrP) To determine whether Bac-rPrPSc is spontaneously produced in intermittent ultrasonic reactions [69]
Mouse PrP (MoPrP, residues 89–230) in complex with a nanobody (Nb484) To understand the role of the hydrophobic region in forming infectious prion at the molecular level [70]
Transgenic mice expressing elk PrP (TgElk) To test vaccine candidates against chronic wasting disease [71]
rPrP from bank vole (BV rPrP) To develop a method to dry and preserve the prion protein for long term storage [72]
Murine rPrP To study how RNA can influence the aggregation of the murine rPrP [73]
Pr from the brains of clinically sick mice that had been intracerebrally inoculated with the Rocky Mountain Laboratory (RML) prion strain To demonstrate that prions are not directly neurotoxic and that toxicity present in infected brain tissue can be distinguished from infectious prions [74]
BV rPrP (amino acids 23–231) To understand how different cofactors modulate prion strain generation and selection [75]
Recent studies have shown that the infectivity of prions and their neurotoxicity may not be related to each other. Therefore, it is important to distinguish directly infective prions and those with a toxic effect, since the current hypothesis suggests that it is not the prions themselves that are toxic but another type of protein responsible for the toxicity of the disease. This species may be a by-product of prion formation, in a non-pathway amyloid PrP structure or even a non-protein whose formation is catalyzed by a prion [76]. Thus, using highly purified infectious prions, it was demonstrated that prions are not directly neurotoxic and that the toxicity presented in infected brain tissue may be different from infectious prions [74].
rPrP was obtained using the insect baculovirus cell expression system (Bac-rPrP) [69] to determine whether pathogenic Bac-pathogenic PrP (PrPSc) is produced spontaneously in intermittent ultrasound reactions. No spontaneous formation of Bac-rPrPSc was observed at 37 °C, but when the reaction temperature increased to 45 °C, Bac-rPrPSc was formed in all samples studied. Some variants of Bac-rPrPSc were transmitted to mice, but when the reaction was repeated for 40 cycles, transmissibility was lost. It is noteworthy that various variants of Bac-rPrPSc, including nontransmissive ones, were characterized by resistance to proteinase K and were dependent on the presence of cofactors during amplification. However, their characteristics also disappeared after 40 reaction cycles, and the variety converged on one variant. These results show that different variants of Bac-rPrPSc are generated with different transmissivity to mice and structural properties; variants of Bac-rPrPSc compete with each other and gradually converge to a variant with a slightly higher amplification rate.
To understand the role of the hydrophobic region in the formation of an infectious prion at the molecular level, X-rays of crystal structures of mouse PrP (MoPrP, residues 89–230) in complex with a nanobody (Nb484) were obtained [70]. Using a rPrP reproduction system, it has been shown that binding of Nb484 to the hydrophobic region of MoPrP effectively inhibits the reproduction of proteinase-resistant PrPSc and the infectivity of prions. In addition, when added to cultured mouse brain slices in high concentrations, Nb484 did not exhibit neurotoxicity, which is sharply different from other neurotoxic antibodies against PrP. Thus, Nb484 may be a potential therapeutic agent against prion disease.
Five groups of transgenic mice expressing elk PrP (TgElk) were vaccinated with either one CpG adjuvant or one of four rPrP immunogens: deer dimer (Ddi); deer monomer (Dmo); mouse dimer (Mdi) and mouse monomer (Mmo) [71]. Then mice were intraperitoneally infected with prions of chronic wasting disease (CWD). All vaccinated mice developed anti-PrP antibody titers detected by ELISA. It is important to note that all four vaccinated groups survived longer than the control group, while in the group immunized with Mmo, the average survival time increased by 60% compared to the control group (183 vs. 114 days after inoculation).
Thus, the use of recombinant forms of prions allows researchers to study their immunogenicity and to develop novel vaccines.
In order to establish how various cofactors modulate the formation and selection of prion strains, PMCA was used to generate a variety of infectious rPrP strains by multiplication in the presence of brain homogenate [75]. It is known that brain homogenate contains certain cofactors whose identity is only partially known and which facilitate the transformation of normal PrP (PrPC) into PrPSc. A mixture of various infectious prion strains was obtained and introduced into the brain homogenate, where various polyanionic cofactors were present. These cofactors could control the evolution of mixed prion populations toward the development of specific strains (types of conformations). As a result, it has been shown that various infectious rPrP can be obtained in vitro. Their specific conformation (strain) depends on the cofactors available during reproduction.
These observations are very important for understanding the pathogenesis of prion diseases and their ability to reproduce in various tissues and hosts.
The RT-QuIC method can be used to detect pathogenic PrP in various biological tissues of humans and animals. However, this method requires a continuous supply of freshly purified PrP and thus is not available in a diagnostic laboratory. To solve the issue, a method for obtaining a rPrP has been developed [72]. Lyophilized rPrP from bank vole (BV rPrP) can be stored for a long time before use, as well as be transported at certain temperatures to appropriate diagnostic laboratories, which can facilitate implementation of the RT-QuIC method as a diagnostic tool [72].
Nucleic acids have been shown in recent studies to act as potential cofactors of protein aggregation and prionogenesis. For example, RNAs, regardless of their sequence, source and size, modulate rPrP aggregation in a bimodal manner, affecting both the degree and the rate of rPrP aggregation depending on the concentration [73].
 

This entry is adapted from the peer-reviewed paper 10.3390/ijms24054630

References

  1. Micoli, F.; Bagnoli, F.; Rappuoli, R.; Serruto, D. The role of vaccines in combatting antimicrobial resistance. Nat. Rev. Microbiol. 2021, 19, 287–302.
  2. Shilova, O.; Shramova, E.; Proshkina, G.; Deyev, S. Natural and designed toxins for precise therapy: Modern approaches in experimental oncology. Int. J. Mol. Sci. 2021, 22, 4975.
  3. Marzhoseyni, Z.; Shojaie, L.; Tabatabaei, S.A.; Movahedpour, A.; Safari, M.; Esmaeili, D.; Mahjoubin-Tehran, M.; Jalili, A.; Morshedi, K.; Khan, H.; et al. Streptococcal bacterial components in cancer therapy. Cancer Gene Ther. 2022, 29, 141–155.
  4. Khatuntseva, E.A.; Nifantiev, N.E. Cross reacting material (CRM197) as a carrier protein for carbohydrate conjugate vaccines targeted at bacterial and fungal pathogens. Int. J. Biol. Macromol. 2022, 218, 775–798.
  5. Wulff, H.; Christophersen, P.; Colussi, P.; Chandy, K.G.; Yarov-Yarovoy, V. Antibodies and venom peptides: New modalities for ion channels. Nat. Rev. Drug. Discov. 2019, 18, 339–357.
  6. Oliveira, L.V.; Wang, R.; Specht, C.A.; Levitz, S.M. Vaccines for human fungal diseases: Close but still a long way to go. Vaccines 2021, 6, 33.
  7. Geron, M. Production and purification of recombinant toxins. In Snake and Spider Toxins; Humana: New York, NY, USA, 2020; Volume 2068, pp. 73–84.
  8. Rodrigues, R.R.; Ferreira, M.R.A.; Kremer, F.S.; Donassolo, R.A.; Júnior, C.M.; Alves, M.L.F.; Conceição, F.R. Recombinant vaccine design against Clostridium spp. toxins using immunoinformatics tools. In Vaccine Design; Humana: New York, NY, USA, 2022; Volume 2012, pp. 457–470.
  9. Pons, L.; Vilain, C.; Volteau, M.; Picaut, P. Safety and pharmacodynamics of a novel recombinant botulinum toxin E (rBoNT-E): Results of a phase 1 study in healthy male subjects compared with abobotulinumtoxinA (Dysport®). J. Neurol. Sci. 2019, 407, 116516.
  10. Fredericks, L.R.; Lee, M.D.; Crabtree, A.M.; Boyer, J.M.; Kizer, E.A.; Taggart, N.T.; Roslund, C.R.; Hunter, S.S.; Kennedy, C.B.; Willmore, C.G.; et al. The species-specific acquisition and diversification of a K1-like family of killer toxins in budding yeasts of the Saccharomycotina. PLoS Genet. 2021, 17, e1009341.
  11. Giesselmann, E.; Becker, B.; Schmitt, M.J. Production of fluorescent and cytotoxic K28 killer toxin variants through high cell density fermentation of recombinant Pichia pastoris. Microb. Cell Fact. 2017, 16, 228.
  12. Gier, S.; Schmitt, M.J.; Breinig, F. Expression of K1 toxin derivatives in Saccharomyces cerevisiae mimics treatment with exogenous toxin and provides a useful tool for elucidating K1 mechanisms of action and immunity. Toxins 2017, 9, 345.
  13. Carboni, G.; Fancello, F.; Zara, G.; Zara, S.; Ruiu, L.; Marova, I.; Pinnac, G.; Budroni, M.; Mannazzu, I. Production of a lyophilized ready-to-use yeast killer toxin with possible applications in the wine and food industries. Int. J. Food Microbiol. 2020, 335, 108883.
  14. Chessa, R.; Landolfo, S.; Ciani, M.; Budroni, M.; Zara, S.; Ustun, M.; Cakar, Z.P.; Mannazzu, I. Biotechnological exploitation of Tetrapisisporaphaffii killer toxin: Heterologous production in Komagataellaphaffii (Pichia pastoris). Appl. Microbiol. Biotechnol. 2017, 101, 2931–2942.
  15. Salazar, M.H.; Clement, H.; Corrales-García, L.L.; Sánchez, J.; Cleghorn, J.; Zamudio, F.; Possani, L.D.; Acosta, H.; Corzo, G. Heterologous expression of four recombinant toxins from Panamanian scorpions of the genus Tityus and Centruroides for production of antivenom. Toxicon 2022, 13, 100090.
  16. Timofeev, S.; Mitina, G.; Rogozhin, E.; Dolgikh, V. Expression of spider toxin in entomopathogenic fungus Lecanicilliummuscarium and selection of the strain showing efficient secretion of the recombinant protein. FEMS Microbiol. Lett. 2019, 366, fnz181.
  17. Esipov, R.S.; Stepanenko, V.N.; Zvereva, I.O.; Makarov, D.A.; Kostromina, M.A.; Kostromina, T.I.; Muravyova, T.I.; Miroshnikov, A.I.; Grishin, E.V. Biotechnological method for production of recombinant peptide analgesic (purotoxin-1) from Geolycosa sp. spider poison. Russ. J. Bioorganic Chem. 2018, 44, 32–40.
  18. Shelukhina, I.V.; Zhmak, M.N.; Lobanov, A.V.; Ivanov, I.A.; Garifulina, A.I.; Kravchenko, I.N.; Rasskazova, E.A.; Salmova, M.A.; Tukhovskaya, E.A.; Rykov, V.A.; et al. Azemiopsin, a selective peptide antagonist of muscle nicotinic acetylcholine receptor: Preclinical evaluation as a local muscle relaxant. Toxins 2018, 10, 34.
  19. Babenko, V.V.; Ziganshin, R.H.; Weise, C.; Dyachenko, I.; Shaykhutdinova, E.; Murashev, A.N.; Zhmak, M.; Starkov, V.; Hoang, A.N.; Tsetlin, V.; et al. Novel bradykinin-potentiating peptides and three-finger toxins from viper venom: Combined NGS venom gland transcriptomics and quantitative venom proteomics of the Azemiops feae viper. Biomedicines 2020, 8, 249.
  20. Romero-Giraldo, L.E.; Pulido, S.; Berrío, M.A.; Flórez, M.F.; Rey-Suárez, P.; Nuñez, V.; Pereañez, J.A. Heterologous expression and immunogenic potential of the most abundant phospholipase a2 from coral snake Micrurus dumerilii to develop antivenoms. Toxins 2022, 14, 825.
  21. Esipov, R.S.; Makarov, D.A.; Stepanenko, V.N.; Kostromina, M.A.; Muravyova, T.I.; Andreev, Y.A.; Dyachenko, I.A.; Kozlov, S.A.; Grishin, E.V. Pilot production of the recombinant peptide toxin of Heteractis crispa as a potential analgesic by intein-mediated technology. Protein Expr. Purif. 2018, 145, 71–76.
  22. Tereshin, M.N.; Komyakova, A.M.; Stepanenko, V.N.; Myagkikh, I.V.; Shoshina, N.S.; Korolkova, Y.V.; Leychenko, E.V.; Kozlov, S.A. Optimized method for the recombinant production of a sea anemone’s peptide. Mendeleev Commun. 2022, 32, 745–746.
  23. Fellermann, M.; Stemmer, M.; Noschka, R.; Wondany, F.; Fischer, S.; Michaelis, J.; Stenger, S.; Barth, H. Clostridium botulinum C3 toxin for selective delivery of cargo into dendritic cells and macrophages. Toxins 2022, 14, 711.
  24. Fellermann, M.; Huchler, C.; Fechter, L.; Kolb, T.; Wondany, F.; Mayer, D.; Michaelis, J.; Stenger, S.; Mellert, K.; Möller, P.; et al. Clostridial C3 toxins enter and intoxicate human dendritic cells. Toxins 2020, 12, 563.
  25. Eisele, J.; Schreiner, S.; Borho, J.; Fischer, S.; Heber, S.; Endres, S.; Fellermann, M.; Wohlgemuth, L.; Huber-Lang, M.; Fois, G.; et al. The pore- forming subunit C2IIa of the binary Clostridium botulinum C2 toxin reduces the chemotactic translocation of human polymorphonuclear leukocytes. Front. Pharmacol. 2022, 13, 810611.
  26. El-Chami, D.; Al Haddad, M.; Abi-Habib, R.; El-Sibai, M. Recombinant anthrax lethal toxin inhibits cell motility and invasion in breast cancer cells through the dysregulation of Rho GTPases. Oncol. Lett. 2021, 21, 163.
  27. Rudenko, N.; Nagel, A.; Zamyatina, A.; Karatovskaya, A.; Salyamov, V.; Andreeva-Kovalevskaya, Z.; Siunov, A.; Kolesnikov, A.; Shepelyakovskaya, A.; Boziev, K.; et al. A monoclonal antibody against the C-terminal domain of Bacillus cereus hemolysin II inhibits HlyII cytolytic activity. Toxins 2020, 12, 806.
  28. Rudenko, N.; Siunov, A.; Zamyatina, A.; Melnik, B.; Nagel, A.; Karatovskaya, A.; Borisova, M.; Shepelyakovskaya, A.; Andreeva-Kovalevskaya, Z.; Kolesnikov, A.; et al. The C-terminal domain of Bacillus cereus hemolysin II oligomerizes by itself in the presence of cell membranes to form ion channels. Int. J. Biol. Macromol. 2022, 200, 416–427.
  29. Maksimov, I.V.; Blagova, D.K.; Veselova, S.V.; Sorokan, A.V.; Burkhanova, G.F.; Cherepanova, E.A.; Sarvarova, E.R.; Rumyantsev, S.D.; Alekseev, V.Y.; Khayrullin, R.M. Recombinant Bacillus subtilis 26DCryChS line with gene Btcry1Ia encoding Cry1Ia toxin from Bacillus thuringiensis promotes integrated wheat defense against pathogen Stagonospora nodorum Berk. and greenbug Schizaphis graminum Rond. Biol. Control 2020, 144, 104242.
  30. Zakharzhevskaya, N.B.; Tsvetkov, V.B.; Vanyushkina, A.A.; Varizhuk, A.M.; Rakitina, D.V.; Podgorsky, V.V.; Vishnyakov, I.E.; Kharlampieva, D.D.; Manuvera, V.A.; Lisitsyn, F.V.; et al. Interaction of bacteroides fragilis toxin with outer membrane vesicles reveals new mechanism of its secretion and delivery. Front. Cell. Infect. Microbiol. 2017, 7, 2.
  31. Voltà-Durán, E.; Sánchez, J.M.; Parladé, E.; Serna, N.; Vazquez, E.; Unzueta, U.; Villaverde, A. The Diphtheria toxin translocation domain impairs receptor selectivity in cancer cell-targeted protein nanoparticles. Pharmaceutics 2022, 14, 2644.
  32. Manoilov, K.Y.; Labyntsev, A.J.; Korotkevych, N.V.; Maksymovych, I.S.; Kolybo, D.V.; Komisarenko, S.V. Particular features of diphtheria toxin internalization by resistant and sensitive mammalian cells. Cytol. Genet. 2018, 52, 353–359.
  33. Chalenko, Y.; Sobyanin, K.; Sysolyatina, E.; Midiber, K.; Kalinin, E.; Lavrikova, A.; Mikhaleva, L.; Ermolaeva, S. Hepatoprotective Activity of InlB321/15, the HGFR Ligand of Bacterial Origin, in CCI4-Induced Acute Liver Injury Mice. Biomedicines 2019, 7, 29.
  34. Abramov, V.M.; Kosarev, I.V.; Motin, V.L.; Khlebnikov, V.S.; Vasilenko, R.N.; Sakulin, V.K.; Machulin, A.V.; Uversky, V.N.; Karlyshev, A.V. Binding of LcrV protein from Yersinia pestis to human T-cells induces apoptosis, which is completely blocked by specific antibodies. Int. J. Biol. Macromol. 2019, 122, 1062–1070.
  35. Ovchinnikov, S.V.; Bikmetov, D.; Livenskyi, A.; Serebryakova, M.; Wilcox, B.; Mangano, K.; Shiriaev, D.I.; Osterman, I.A.; Sergiev, P.V.; Borukhov, S.; et al. Mechanism of translation inhibition by type II GNAT toxin AtaT2. Nucleic Acids Res. 2020, 48, 8617–8625.
  36. Carboni, G.; Marova, I.; Zara, G.; Zara, S.; Budroni, M.; Mannazzu, I. Evaluation of recombinant Kpkt cytotoxicity on HaCaT cells: Further steps towards the biotechnological exploitation yeast killer toxins. Foods 2021, 10, 556.
  37. Gandomkari, M.S.; Ayat, H.; Ahadi, A.M. Recombinantly expressed MeICT, a new toxin from Mesobuthuseupeus scorpion, inhibits glioma cell proliferation and downregulates Annexin A2 and FOXM1 genes. Biotechnol. Lett. 2022, 44, 703–712.
  38. Kuzmenkov, A.I.; Nekrasova, O.V.; Peigneur, S.; Tabakmakher, V.M.; Gigolaev, A.M.; Fradkov, A.F.; Kudryashova, K.S.; Chugunov, A.O.; Efremov, A.G.; Tytgat, J.; et al. KV1. 2 channel-specific blocker from Mesobuthuseupeus scorpion venom: Structural basis of selectivity. Neuropharmacology 2018, 143, 228–238.
  39. Gigolaev, A.M.; Kuzmenkov, A.I.; Peigneur, S.; Tabakmakher, V.M.; Pinheiro-Junior, E.L.; Chugunov, A.O.; Efremov, R.G.; Tytgat, J.; Vassilevski, A.A. Tuning scorpion toxin selectivity: Switching from KV1.1 to KV1.3. Front. Pharmacol. 2020, 11, 1010.
  40. Korolkova, Y.; Maleeva, E.; Mikov, A.; Lobas, A.; Solovyeva, E.; Gorshkov, M.; Andreev, Y.; Peigneur, S.; Tytgat, J.; Kornilov, F.; et al. New insectotoxin from Tibellus oblongus spider venom presents novel adaptation of ICK fold. Toxins 2021, 13, 29.
  41. Terpinskaya, T.I.; Osipov, A.V.; Kryukova, E.V.; Kudryavtsev, D.S.; Kopylova, N.V.; Yanchanka, T.L.; Palukoshka, A.F.; Gondarenko, E.A.; Zhmak, M.N.; Tsetlin, V.I.; et al. α -Conotoxins and α-Cobratoxin promote, while lipoxygenase and cyclooxygenase inhibitors suppress the proliferation of glioma C6 cells. Mar. Drugs 2021, 19, 118.
  42. Makarova, Y.V.; Kryukova, E.V.; Shelukhina, I.V.; Lebedev, D.S.; Andreeva, T.V.; Ryazantsev, D.Y.; Balandin, S.V.; Ovchinnikova, T.V.; Tsetlin, V.I.; Utkin, Y.N. The first recombinant viper three-finger toxins: Inhibition of muscle and neuronal nicotinic acetylcholine receptors. Dokl. Biochem. Biophys. 2018, 479, 127–130.
  43. Son, L.; Kryukova, E.; Ziganshin, R.; Andreeva, T.; Kudryavtsev, D.; Kasheverov, I.; Tsetlin, V.; Utkin, Y. Novel three-finger neurotoxins from Naja melanoleuca cobra venom interact with GABAA and nicotinic acetylcholine receptors. Toxins 2021, 13, 164.
  44. Kvetkina, A.; Malyarenko, O.; Pavlenko, A.; Dyshlovoy, S.; von Amsberg, G.; Ermakova, S.; Leychenko, E. Sea anemone Heteractis crispa actinoporin demonstrates in vitro anticancer activities and prevents HT-29 colorectal cancer cell migration. Molecules 2020, 25, 5979.
  45. Godakova, S.A.; Noskov, A.N.; Vinogradova, I.D.; Ugriumova, G.A.; Solovyev, A.I.; Esmagambetov, I.B.; Tukhvatulin, A.I.; Logunov, D.Y.; Naroditsky, B.S.; Shcheblyakov, D.V.; et al. Camelid VHHs fused to human Fc fragments provide long term protection against botulinum neurotoxin a in mice. Toxins 2019, 11, 464.
  46. Rodrigues, R.R.; Ferreira, M.R.A.; Donassolo, R.A.; Alves, M.L.F.; Motta, J.F.; Moreira, C., Jr.; Salvarani, F.M.; Moreira, A.N.; Conceição, F.R. Evaluation of the expression and immunogenicity of four versions of recombinant Clostridium perfringens beta toxin designed by bioinformatics tools. Anaerobe 2021, 69, 102326.
  47. Ferreira, D.V.; dos Santos, F.D.; da Cunha, C.E.P.; Moreira, C., Jr.; Donassolo, R.A.; Magalhães, C.G.; Belo Reis, A.S.; Oliveira, C.M.C.; Barbosa, J.D.; Leite, F.P.L.; et al. Immunogenicity of Clostridium perfringens epsilon toxin recombinant bacterin in rabbit and ruminants. Vaccine 2018, 36, 7589–7592.
  48. Karpov, D.S.; Goncharenko, A.V.; Usachev, E.V.; Vasina, D.V.; Divisenko, E.V.; Chalenko, Y.M.; Pochtovyi, A.A.; Ovchinnikov, R.S.; Makarov, V.V.; Yudin, S.M.; et al. A Strategy for the Rapid Development of a Safe Vibrio cholerae Candidate Vaccine Strain. Int. J. Mol. Sci. 2021, 22, 11657.
  49. Alomran, N.; Blundell, P.; Alsolaiss, J.; Crittenden, E.; Ainsworth, S.; Dawson, C.A.; Edge, R.J.; Hall, S.R.; Harrison, R.A.; Wilkinson, M.C.; et al. Exploring the utility of recombinant snake venom serine protease toxins as immunogens for generating experimental snakebite antivenoms. Toxins 2022, 14, 443.
  50. Alomran, N.; Chinnappan, R.; Alsolaiss, J.; Casewell, N.R.; Zourob, M. Exploring the utility of ssDNA aptamers directed against snake venom toxins as new therapeutics for snakebite envenoming. Toxins 2022, 14, 469.
  51. Neuschäfer-Rube, F.; Pathe-Neuschäfer-Rube, A.; Püschel, G.P. Discrimination of the activity of low-affinity wild-type and high-affinity mutant recombinant BoNT/B by a SIMA cell-based reporter release assay. Toxins 2022, 14, 65.
  52. Martin, T.; Möglich, A.; Felix, I.; Förtsch, C.; Rittlinger, A.; Palmer, A.; Denk, S.; Schneider, J.; Notbohm, L.; Vogel, M.; et al. Rho-inhibiting C2IN-C3 fusion toxin inhibits chemotactic recruitment of human monocytes ex vivo and in mice in vivo. Arch. Toxicol. 2018, 92, 323–336.
  53. Hashemi Yeganeh, H.; Heiat, M.; Kieliszek, M.; Alavian, S.M.; Rezaie, E. DT389-YP7, a recombinant immunotoxin against glypican-3 that inhibits hepatocellular cancer cells: An in vitro study. Toxins 2021, 13, 749.
  54. Cheung, L.S.; Fu, J.; Kumar, P.; Kumar, A.; Urbanowski, M.E.; Ihms, E.A.; Parveen, S.; Bullen, C.K.; Patrick, G.J.; Harrison, R.; et al. Second-generation IL-2 receptor-targeted diphtheria fusion toxin exhibits antitumor activity and synergy with anti–PD-1 in melanoma. Proc. Natl. Acad. Sci. USA 2019, 116, 3100–3105.
  55. Schmohl, J.U.; Todhunter, D.; Taras, E.; Bachanova, V.; Vallera, D.A. Development of a deimmunized bispecific immunotoxin dDT2219 against B-cell malignancies. Toxins 2018, 10, 32.
  56. Ryabchevskaya, E.M.; Evtushenko, A.; Granovskiy, D.L.; Ivanov, P.A.; Atabekov, J.G.; Kondakova, O.A.; Nikitin, N.A.; Karpova, O.V. Two approaches for the stabilization of Bacillus anthracis recombinant protective antigen. Hum. Vaccines Immunother. 2021, 17, 560–565.
  57. Ryabchevskaya, E.M.; Granovskiy, D.L.; Evtushenko, E.A.; Ivanov, P.A.; Kondakova, O.A.; Nikitin, N.A.; Karpova, O.V. Designing stable Bacillus anthracis antigens with a view to recombinant anthrax vaccine development. Pharmaceutics 2022, 14, 806.
  58. Evtushenko, E.A.; Kondakova, O.A.; Arkhipenko, M.V.; Kravchenko, T.B.; Bakhteeva, I.V.; Timofeev, V.S.; Nikitin, N.A.; Karpova, O.V. New formulation of a recombinant anthrax vaccine stabilised with structurally modified plant viruses. Front. Microbiol. 2022, 13, 1003969.
  59. Shulcheva, I.; Shchannikova, M.; Melnik, B.; Fursova, K.; Semushina, S.; Zamyatina, A.; Oleinikov, V.; Brovko, F. The zinc ions stabilize the three-dimensional structure and are required for the binding of staphylococcal enterotoxin-like protein P (SEIP) with MHC-II receptors. Protein Expr. Purif. 2022, 197, 106098.
  60. Gholami, N.; Cohan, R.A.; Razavi, A.; Bigdeli, R.; Dashbolaghi, A.; Asgary, V. Cytotoxic and apoptotic properties of a novel nano-toxin formulation based on biologically synthesized silver nanoparticle loaded with recombinant truncated Pseudomonas exotoxin A. J. Cell. Physiol. 2020, 235, 3711–3720.
  61. Royal, J.M.; Reeves, M.A.; Matoba, N. Repeated oral administration of a KDEL-tagged recombinant cholera toxin B subunit effectively mitigates dss colitis despite a robust immunogenic response. Toxins 2019, 11, 678.
  62. Nekrasova, O.V.; Primak, A.L.; Ignatova, A.A.; Novoseletsky, V.N.; Geras’kina, O.V.; Kudryashova, K.S.; Yakimov, S.A.; Kirpichnikov, M.P.; Arseniev, A.S.; Feofanov, A.V. N-terminal tagging with GFP enhances selectivity of agitoxin 2 to Kv1.3-channel binding site. Toxins 2020, 12, 802.
  63. Calabria, P.A.; Shimokawa-Falcão, L.H.A.; Colombini, M.; Moura-da-Silva, A.M.; Barbaro, K.C.; Faquim-Mauro, E.L.; Magalhaes, G.S. Design and production of a recombinant hybrid toxin to raise protective antibodies against Loxosceles spider venom. Toxins 2019, 11, 108.
  64. Logashina, Y.A.; Lubova, K.I.; Maleeva, E.E.; Palikov, V.A.; Palikova, Y.A.; Dyachenko, I.A.; Andreev, Y.A. Analysis of structural determinants of peptide MS 9a-1 essential for potentiating of TRPA1 channel. Mar. Drugs 2022, 20, 465.
  65. Mannazzu, I.; Domizio, P.; Carboni, G.; Zara, S.; Zara, G.; Comitini, F.; Budroni, M.; Ciani, M. Yeast killer toxins: From ecological significance to application. Crit. Rev. Biotechnol. 2019, 39, 603–617.
  66. Giovati, L.; Ciociola, T.; De Simone, T.; Conti, S.; Magliani, W. Wickerhamomyces yeast killer toxins’ medical applications. Toxins 2021, 13, 655.
  67. Leychenko, E.; Isaeva, M.; Tkacheva, E.; Zelepuga, E.; Kvetkina, A.; Guzev, K.; Monastyrnaya, M.; Kozlovskaya, E. Multigene family of pore-forming toxins from sea anemone Heteractis crispa. Mar. Drugs 2018, 16, 183.
  68. Ma, J.; Zhang, J.; Yan, R. Recombinant mammalian prions: The “correctly” misfolded prion protein conformers. Viruses 2022, 14, 1940.
  69. Imamura, M.; Tabeta, N.; Iwamaru, Y.; Takatsuki, H.; Mori, T.; Atarashi, R. Spontaneous generation of distinct prion variants with recombinant prion protein from a baculovirus-insect cell expression system. Biochem. Biophys. Res. Commun. 2022, 613, 67–72.
  70. Abskharon, R.; Wang, F.; Wohlkonig, A.; Ruan, J.; Soror, S.; Giachin, G.; Pardon, E.; Zou, W.; Legname, G.; Ma, J.; et al. Structural evidence for the critical role of the prion protein hydrophobic region in forming an infectious prion. PLoS Pathog. 2019, 15, e1008139.
  71. Abdelaziz, D.H.; Thapa, S.; Brandon, J.; Maybee, J.; Vankuppeveld, L.; McCorkell, R.; Schätzl, H.M. Recombinant prion protein vaccination of transgenic elk PrP mice and reindeer overcomes self-tolerance and protects mice against chronic wasting disease. J. Biol. Chem. 2018, 293, 19812–19822.
  72. Hwang, S.; Tatum, T.; Lebepe-Mazur, S.; Nicholson, E.M. Preparation of lyophilized recombinant prion protein for TSE diagnosis by RT-QuIC. BMC Res. Notes 2018, 11, 895.
  73. Kovachev, P.S.; Gomes, M.P.; Cordeiro, Y.; Ferreira, N.C.; Valadão, L.P.F.; Ascari, L.M.; Rangel, L.P.; Silva, J.L.; Sanyal, S. RNA modulates aggregation of the recombinant mammalian prion protein by direct interaction. Sci. Rep. 2019, 9, 12406.
  74. Benilova, I.; Reilly, M.; Terry, C.; Wenborn, A.; Schmidt, C.; Marinho, A.T.; Risse, E.; Al-Doujaily, H.; WigginsDeOliveira, M.; Sandberg, M.K.; et al. Highly infectious prions are not directly neurotoxic. Proc. Natl. Acad. Sci. USA 2020, 117, 23815.
  75. Fernández-Borges, N.; Di Bari, M.A.; Eraña, H.; Sánchez-Martín, M.; Pirisinu, L.; Parra, B.; Elezgarai, S.R.; Vanni, I.; López-Moreno, R.; Vaccari, G.; et al. Cofactors influence the biological properties of infectious recombinant prions. Acta. Neuropathol. 2018, 135, 179–199.
  76. Jack, K.; Jackson, G.S.; Bieschke, J. Essential components of synthetic infectious prion formation de novo. Biomolecules 2022, 12, 1694.
More
© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license; additional terms may apply. By using this site, you agree to the Terms and Conditions and Privacy Policy.
This entry is offline, you can click here to edit this entry!
Video Production Service
Feedback