Component of the methyl-coenzyme M reductase (MCR) I that catalyzes the reductive cleavage of methyl-coenzyme M (CoM-S-CH3 or 2-(methylthio)ethanesulfonate) using coenzyme B (CoB or 7-mercaptoheptanoylthreonine phosphate) as reductant which results in the production of methane and the mixed heterodisulfide of CoB and CoM (CoM-S-S-CoB). This is the final step in methanogenesis. coenzyme B + methyl-coenzyme M = coenzyme M-coenzyme B heterodisulfide + methane Binds 2 coenzyme F430 non-covalently per MCR complex. Coenzyme F430 is a yellow nickel porphinoid. Methyl-coenzyme-M reductase is activated when the enzyme-bound coenzyme F430 is reduced to the Ni(I) oxidation state. One-carbon metabolism; methyl-coenzyme M reduction; methane from methyl-coenzyme M: step 1/1. MCR is a hexamer of two alpha, two beta, and two gamma chains, forming a dimer of heterotrimers. There are two MCR complexes in this bacteria. MCR II is expressed in the early growth phase. Late growth cells contain mostly MCR I. Belongs to the methyl-coenzyme M reductase beta subunit family.