Identification of HcgC as a SAM‐Dependent Pyridinol Methyltransferase in [Fe]‐Hydrogenase Cofactor Biosynthesis. (8th July 2016)

• Record Type: Journal Article
• Authors: Fujishiro, Takashi; Bai, Liping; Xu, Tao; Xie, Xiulan; Schick, Michael; Kahnt, Jörg; Rother, Michael; Hu, Xile; Ermler, Ulrich; Shima, Seigo
• Is Part Of: Angewandte Chemie. Volume 128:Number 33(2016)
• Page Start: 9800
• Page End: 9803
• Publication Date: 2016-07-08
• Subjects: Cofaktoren -- Enzyme -- Hydrogenasen -- Methyltransferasen -- Proteinstrukturen; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201604352
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Previous 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.