Structural highlights
FunctionPublication Abstract from PubMedPrevious retrosynthetic and isotope-labeling studies have indicated that biosynthesis of the iron guanylylpyridinol (FeGP) cofactor of [Fe]-hydrogenase requires a methyltransferase. This hypothetical enzyme covalently attaches the methyl group at the 3-position of the pyridinol ring. We describe the identification of HcgC, a gene product of the hcgA-G cluster responsible for FeGP cofactor biosynthesis. It acts as an S-adenosylmethionine (SAM)-dependent methyltransferase, based on the crystal structures of HcgC and the HcgC/SAM and HcgC/S-adenosylhomocysteine (SAH) complexes. The pyridinol substrate, 6-carboxymethyl-5-methyl-4-hydroxy-2-pyridinol, was predicted based on properties of the conserved binding pocket and substrate docking simulations. For verification, the assumed substrate was synthesized and used in a kinetic assay. Mass spectrometry and NMR analysis revealed 6-carboxymethyl-3,5-dimethyl-4-hydroxy-2-pyridinol as the reaction product, which confirmed the function of HcgC. Identification of HcgC as a SAM-Dependent Pyridinol Methyltransferase in [Fe]-Hydrogenase Cofactor Biosynthesis.,Fujishiro T, Bai L, Xu T, Xie X, Schick M, Kahnt J, Rother M, Hu X, Ermler U, Shima S Angew Chem Int Ed Engl. 2016 Jul 8. doi: 10.1002/anie.201604352. PMID:27391308[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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