Identification of HcgC as a SAM‐Dependent Pyridinol Methyltransferase in [Fe]‐Hydrogenase Cofactor Biosynthesis |
| |
| Authors: | Dr. Takashi Fujishiro Liping Bai Dr. Tao Xu Dr. Xiulan Xie Dr. Michael Schick Jörg Kahnt Prof. Dr. Michael Rother Prof. Dr. Xile Hu Dr. Ulrich Ermler Dr. Seigo Shima |
| |
| Affiliation: | 1. Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany;2. Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Sakura-ku, Saitama, Japan;3. Institute of Chemical Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland;4. Department of Chemistry, Philipps Universit?t Marburg, Marburg, Germany;5. Institut für Mikrobiologie, Technische Universit?t Dresden, Dresden, Germany;6. Max-Planck-Institut für Biophysik, Frankfurt/Main, Germany;7. PRESTO, Japan, Science and Technology Agency, JST, Saitama, Japan |
| |
| 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. |
| |
| Keywords: | cofactors enzymes hydrogenases methyltransferases protein structures |
|
|
