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Title: Structure of the cobalamin-binding protein of a putative O-demethylase from Desulfitobacterium hafniense DCB-2

The first crystal structure of the vitamin B12-binding protein from a three-component O-demethylase enzyme system is reported. During O-demethylation methyl groups are transferred from phenyl methyl ethers to tetrahydrofolate via methyl-B12 intermediates. This study describes the identification and the structural and spectroscopic analysis of a cobalamin-binding protein (termed CobDH) implicated in O-demethylation by the organohalide-respiring bacterium Desulfitobacterium hafniense DCB-2. The 1.5 Å resolution crystal structure of CobDH is presented in the cobalamin-bound state and reveals that the protein is composed of an N-terminal helix-bundle domain and a C-terminal Rossmann-fold domain, with the cobalamin coordinated in the base-off/His-on conformation similar to other cobalamin-binding domains that catalyse methyl-transfer reactions. EPR spectroscopy of CobDH confirms cobalamin binding and reveals the presence of a cob(III)alamin superoxide, indicating binding of oxygen to the fully oxidized cofactor. These data provide the first structural insights into the methyltransferase reactions that occur during O-demethylation by D. hafniense.
Authors:
; ; ;  [1]
  1. University of Manchester, 131 Princess Street, Manchester M1 7DN (United Kingdom)
Publication Date:
OSTI Identifier:
22347819
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica. Section D: Biological Crystallography; Journal Volume: 69; Journal Issue: Pt 8; Other Information: PMCID: PMC3727330; PMID: 23897483; PUBLISHER-ID: be5232; OAI: oai:pubmedcentral.nih.gov:3727330; Copyright (c) Sjuts et al. 2013; This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
Denmark
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; BOUND STATE; CRYSTAL STRUCTURE; CRYSTALS; ELECTRON SPIN RESONANCE; OXYGEN; RESOLUTION; SPECTROSCOPY