Structural Plasticity within 3-Hydroxy-3-Methylglutaryl Synthases Catalyzing the First Step of β-Branching in Polyketide Biosynthesis Underpins a Dynamic Mechanism of Substrate Accommodation.

ABSTRACT: Understanding how enzymes have been repurposed by evolution to carry out new functions is a key goal of mechanistic enzymology. In this study we aimed to identify the adaptations required to allow the 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGCS) enzymes of primary isoprenoid assembly to function in specialized polyketide biosynthetic pathways, where they initiate β-branching. This role notably necessitates that the HMG synthases (HMGSs) act on substrates tethered to noncatalytic acyl carrier protein (ACP) domains instead of coenzyme A, and accommodation of substantially larger chains within the active sites. Here, we show using a combination of X-ray crystallography and small-angle X-ray scattering, that a model HMGS from the virginiamycin system exhibits markedly increased flexib

SUBMITTER: Collin S 

PROVIDER: S-EPMC11522927 | biostudies-literature | 2024 Oct

REPOSITORIES: biostudies-literature