Engineering of PKS Megaenzymes—A Promising Way to Biosynthesize High-Value Active Molecules

Polyketide reductases in defense‐related parasorboside biosynthesis in Gerbera hybrida share processing strategies with microbial polyketide synthase systems

“…In bacteria and fungi, functional modules like KR, DH, ER and CYC are commonly present in type I and II PKS systems. They act on the linear intermediates and are required for the correct region‐specific cyclization of the growing chain (Fischbach & Walsh, 2006; Hertweck, 2009; Neves et al ., 2021). The production of lactones as derailment products has been observed in many type I and II PKS initiated pathways when the KR was missing or blocked, such as in the type I PKS catalyzed 6‐MSA biosynthesis (Campuzano & Shoolingin‐Jordan, 1998) or type II PKS initiated actinorhodin biosynthesis, in which an SDR type KR is involved (Hadfield et al ., 2004).…”

“…Besides essential functional domains or modules like acyl carrier proteins (ACP) and keto synthases (KS) for conducting starter loading and chain extension, they also contain optional tailoring domains or modules such as ketoreductases (KR), dehydratases (DH), enoyl reductases (ER) and cyclases (CYC; Hertweck, 2009; Neves et al ., 2021). Selective manipulations of growing polyketide chains performed by these tailoring proteins are one of the main factors contributing to the diversity of fungal and bacterial polyketides (Hertweck, 2009; Neves et al ., 2021). Type III PKSs, however, are simple homodimeric KSs that use a single active site to employ starter units and to perform iteratively decarboxylative condensations.…”

Path to Actinorhodin: Regio- and Stereoselective Ketone Reduction by a Type II Polyketide Ketoreductase Revealed in Atomistic Detail

“…In this work, we combine protein−protein docking, molecular dynamics (MD) simulations, 2D protein-NMR spectroscopy, and hybrid quantum mechanics/molecular mechanics (QM/ MM) simulations to obtain detailed information on actKR− actACP binding and actKR−octaketide interactions: our aim is to provide a unified picture of actKR structure and function and address the lack of fundamental knowledge on type II PKSs. 1,17,22 ■ MATERIALS AND METHODS…”

“…Extensive work by Tsai and co-workers has found the KR to be capable of remarkable regio- and stereocontrol 5 − 8 and this class of enzymes has attracted interest for their use as biocatalysts in the stereoselective synthesis of small chiral alcohols from achiral ketones. 9 − 14 KRs can be mutated to alter and tune their biocatalytic properties as standalone enzymes or used in “combinatorial biosynthesis” alongside other enzyme components from a PKS to produce polyketide derivatives with novel functionality, 15 − 17 for example, with altered regio- or stereochemistry.…”

“…Most solved enzyme-ACP complexes − feature FASs, − , and only two feature a PKS component (namely, KS). , Moreover, to study protein–substrate interactions, a complex with act ACP- 1 is required, but this is unfeasible. In this work, we combine protein–protein docking, molecular dynamics (MD) simulations, 2D protein-NMR spectroscopy, and hybrid quantum mechanics/molecular mechanics (QM/MM) simulations to obtain detailed information on act KR– act ACP binding and act KR–octaketide interactions: our aim is to provide a unified picture of act KR structure and function and address the lack of fundamental knowledge on type II PKSs. ,, …”