A Carboxylate Shift Regulates Dioxygen Activation by the Diiron Nonheme β-Hydroxylase CmlA upon Binding of a Substrate-Loaded Nonribosomal Peptide Synthetase.

ABSTRACT: The first step in the nonribosomal peptide synthetase (NRPS)-based biosynthesis of chloramphenicol is the β-hydroxylation of the precursor l-p-aminophenylalanine (l-PAPA) catalyzed by the monooxygenase CmlA. The active site of CmlA contains a dinuclear iron cluster that is reduced to the diferrous state (WT^R) to initiate O₂ activation. However, rapid O₂ activation occurs only when WT^R is bound to CmlP, the NRPS to which l-PAPA is covalently attached. Here the X-ray crystal structure of WT^R is reported, which is very similar to that of the as-isolated diferric enzyme in which the irons are coordinately saturated. X-ray absorption spectroscopy is used to investigate the WT^R cluster ligand structure as well as the structures of

SUBMITTER: Jasniewski AJ 

PROVIDER: S-EPMC5258830 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature