Structural insights into modular polyketide synthases: From individual domains to supramolecular assemblies

Abstract Polyketide synthases (PKSs) are large, highly orchestrated enzymatic assemblies that produce a wide array of biologically active compounds with antibiotic, anticancer, and immunosuppressive properties. In particular, modular PKSs (mPKSs) are composed of multiple catalytic domains arranged in an assembly‐line fashion, typically encoded within gene clusters dedicated to polyketide biosynthesis. Recent advances in cryo‐electron microscopy have enabled high‐resolution structural characterization of diverse mPKSs, providing crucial insights into their molecular mechanisms and supporting structure‐guided engineering efforts. In this review, we introduce the individual domain structures and the overall domain architectures of mPKSs as revealed by recent structural studies. Despite the high conservation of individual domains, comparative analyses uncover unexpected variability in the overall architecture of PKS megasynthases, offering explanations for the limitations of earlier engineering attempts and suggesting strategies for more effective metabolic reprogramming.