Methyl-coenzyme M reductase (MCR) catalyzes both the synthesis and the anaerobic oxidation of methane. MCR is one of the few nickel-containing proteins in nature, and its Ni center catalyzes the C–S bond homolysis of methyl-coenzyme M (methyl-SCoM), generating a methyl radical that withdraws a hydrogen atom from coenzyme B (HSCoB) to produce methane and the mixed disulfide CoMSSCoB. Anjali Patwardhan, Stephen Ragsdale, and their collaborators set out to obtain an accurate description of the coordination chemistry at the active Ni(I) site. Their results from spectroscopic, kinetic, structural, and computational studies rule out the presence of direct Ni(I)–sulfur interactions that had been previously suggested. Instead, both methyl-SCoM and CoMSSCoB bind to the active Ni(I) state of MCR through their sulfonate groups, forming hexacoordinated Ni(I)–N/O complexes. The researchers propose that the forward and the reverse MCR reactions rely on long-range electron transfer from the Ni(I)–sulfonate complexes with methyl-SCoM and CoMSSCoB, respectively. Congratulations to Anjali, Steve, and their coauthors for their publication in the Journal of the American Chemical Society (JACS) and for having it selected to be in JACS Spotlights!
April 9, 2021
A research article from the Ragsdale lab is featured in JACS Spotlights
Nickel–sulfonate mode of substrate binding for forward and reverse reactions of methyl-SCoM reductase suggest a radical mechanism involving long-range electron transfer