The Reaction Mechanism of Methyl-Coenzyme M Reductase

Thanyaporn Wongnate1,2, Bojana Ginovska3, Matthew W. Wolf4, Nicolai Lehnert4, Simone Raugei3, and Stephen W. Ragsdale2
1School of Bioresources and Technology and Excellent Center of Waste Utilization and Management (ECoWaste), Pilot Plant Development and Training Institute, King Mongkut’s University of Technology Thonburi, Bangkhunthian, Bangkok 10150, Thailand.
2Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
3Physical Sciences Division, Pacific Northwest National Laboratory, K2-12, Richland, WA 99352, USA.
4Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA.

Methanogens are masters of CO2 reduction. They conserve energy by coupling the reduction of CO2 to CH4, the primary constituent of natural gas. They also generate methane by the reduction of acetic acid, methanol, methane thiol and methylamines. Methanogens produce 109 tons of methane per year and are the major source of the earth’s atmospheric methane. Reverse methanogenesis or anaerobic methane oxidation, which is catalyzed by methanotrophic archaea living in consortia among bacteria that can act as an electron acceptor, is responsible for annual oxidation of 108 tons of methane to CO2. Our studies describe the enzymatic mechanism of the nickel enzyme, methyl-CoM reductase (MCR), the key enzyme in methane synthesis and oxidation. MCR catalyzes the formation of methane and the heterodisulfide (CoBSSCoM) from methyl-Coenzyme M (methyl-CoM) and Coenzyme B (HSCoB). Uncovering the mechanistic and molecular details of MCR catalysis is critical since methane is an abundant and important fuel and is the second (to CO2) most prevalent greenhouse gas.

Time: February, 1 2017

Location: RD1-B2-16, PDTI, BKT