4etw
From Proteopedia
Structure of the Enzyme-ACP Substrate Gatekeeper Complex Required for Biotin Synthesis
Structural highlights
Function[BIOH_SHIFL] The physiological role of BioH is to remove the methyl group introduced by BioC when the pimeloyl moiety is complete. It allows to synthesize pimeloyl-ACP via the fatty acid synthetic pathway through the hydrolysis of the ester bonds of pimeloyl-ACP esters.[HAMAP-Rule:MF_01260] [ACP_SHIF8] Carrier of the growing fatty acid chain in fatty acid biosynthesis.[HAMAP-Rule:MF_01217] Publication Abstract from PubMedAlthough the pimeloyl moiety was long known to be a biotin precursor, the mechanism of assembly of this C7 alpha,omega-dicarboxylic acid was only recently elucidated. In Escherichia coli, pimelate is made by bypassing the strict specificity of the fatty acid synthetic pathway. BioC methylates the free carboxyl of a malonyl thioester, which replaces the usual acetyl thioester primer. This atypical primer is transformed to pimeloyl-acyl carrier protein (ACP) methyl ester by two cycles of fatty acid synthesis. The question is, what stops this product from undergoing further elongation? Although BioH readily cleaves this product in vitro, the enzyme is nonspecific, which made assignment of its physiological substrate problematical, especially because another enzyme, BioF, could also perform this gatekeeping function. We report the 2.05-A resolution cocrystal structure of a complex of BioH with pimeloyl-ACP methyl ester and use the structure to demonstrate that BioH is the gatekeeper and its physiological substrate is pimeloyl-ACP methyl ester. Structure of the enzyme-acyl carrier protein (ACP) substrate gatekeeper complex required for biotin synthesis.,Agarwal V, Lin S, Lukk T, Nair SK, Cronan JE Proc Natl Acad Sci U S A. 2012 Oct 23;109(43):17406-11. doi:, 10.1073/pnas.1207028109. Epub 2012 Oct 8. PMID:23045647[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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