Overall Retention of Methyl Stereochemistry during B₁₂-Dependent Radical SAM Methyl Transfer in Fosfomycin Biosynthesis.

ABSTRACT: Methylcobalamin-dependent radical S-adenosylmethionine (SAM) enzymes methylate non-nucleophilic atoms in a range of substrates. The mechanism of the methyl transfer from cobalt to the receiving atom is still mostly unresolved. Here we determine the stereochemical course of this process at the methyl group during the biosynthesis of the clinically used antibiotic fosfomycin. In vitro reaction of the methyltransferase Fom3 using SAM labeled with ¹H, ²H, and ³H in a stereochemically defined manner, followed by chemoenzymatic conversion of the Fom3 product to acetate and subsequent stereochemical analysis, shows that the overall reaction occurs with retention of configuration. This outcome is consistent with a double-inversion process, first in th

SUBMITTER: McLaughlin MI 

PROVIDER: S-EPMC8158854 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature