Year: 2021
Type: preprint
Abstract: Notwithstanding the “one-module-one-elongation-cycle” paradigm of assembly line polyketide synthases (PKSs), some PKSs harbor modules that iteratively elongate their substrates through a defined number of cycles. While some insights into module iteration, also referred to as “stuttering”, have been derived through in vivo and in vitro analysis of a few PKS modules, a general understanding of the mechanistic principles underlying module iteration remains elusive. This report serves as the first interrogation of a stuttering module from a trans -AT subfamily PKS that is also naturally split across two polypeptides. Previous work has shown that Module 5 of the NOCAP ( noc ardiosis a ssociated p olyketide) synthase iterates precisely three times in the biosynthesis of its polyketide product, resulting in an all trans -configured triene moiety in the polyketide product. Here we describe the intrinsic catalytic properties of this NOCAP synthase module. Through complementary experiments in vitro and in E. coli , the “split-and-stuttering” module was shown to catalyze up to five elongation cycles, although its dehydratase domain ceased to function after three cycles. Unexpectedly, the central olefinic group of this truncated product had a cis configuration. Our findings set the stage for further in-depth analysis of a structurally and functionally unusual PKS module with contextual biosynthetic plasticity. TOC/Abstract Graphic
Institution: Stanford University
Language: English
Subfield: Pharmacology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W3123577942