Multifunctional enzymes are single-polypeptide biocatalysts that contain two or more catalytically competent sites or modules and therefore catalyze more than one enzymatic reaction ^[1][2]. Their defining architectural feature is the intramolecular organization of multiple catalytic modules within one covalent polypeptide chain ^[1][3]. This organization permits consecutive or independent chemical transformations at the individual sites and, in ordered pathways, allows an intermediate generated at one site to access a subsequent active site through substrate channelling [1][4]. In microbial secondary metabolism, multifunctional enzymes integrate multiple catalytic steps into biosynthetic pathways and contribute to metabolic efficiency ^[2]. In biotechnology, the term also covers engineered fusion enzymes in which two or more catalytic activities are combined within one polypeptide chain ^[3]. The essential components are a polypeptide scaffold, two or more catalytically active modules or sites, and, where reactions are consecutive, a structural arrangement that supports intermediate transfer ^[1][3][4].