학술논문
A conserved motif flags acyl carrier proteins for β-branching in polyketide synthesis.
Document Type
Article
Author
Haines, Anthony S; Dong, Xu; Song, Zhongshu; Farmer, Rohit; Williams, Christopher; Hothersall, Joanne; Płoskoń, Eliza; Wattana-amorn, Pakorn; Stephens, Elton R; Yamada, Erika; Gurney, Rachel; Takebayashi, Yuiko; Masschelein, Joleen; Cox, Russell J; Lavigne, Rob; Willis, Christine L; Simpson, Thomas J; Crosby, John; Winn, Peter J; Thomas, Christopher M
Source
Subject
*POLYKETIDE synthases
*CARRIER proteins
*ACYL group
*POLYKETIDES
*CHEMICAL synthesis
*HYDROXYMETHYLGLUTARYL coenzyme A reductases
*MUTAGENESIS
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Language
ISSN
1552-4450
Abstract
Type I polyketide synthases often use programmed β-branching, via enzymes of a 'hydroxymethylglutaryl-CoA synthase (HCS) cassette', to incorporate various side chains at the second carbon from the terminal carboxylic acid of growing polyketide backbones. We identified a strong sequence motif in acyl carrier proteins (ACPs) where β-branching is known to occur. Substituting ACPs confirmed a correlation of ACP type with β-branching specificity. Although these ACPs often occur in tandem, NMR analysis of tandem β-branching ACPs indicated no ACP-ACP synergistic effects and revealed that the conserved sequence motif forms an internal core rather than an exposed patch. Modeling and mutagenesis identified ACP helix III as a probable anchor point of the ACP-HCS complex whose position is determined by the core. Mutating the core affects ACP functionality, whereas ACP-HCS interface substitutions modulate system specificity. Our method for predicting β-carbon branching expands the potential for engineering new polyketides and lays a basis for determining specificity rules. [ABSTRACT FROM AUTHOR]