Figure 1.

MCR metabolic function, purification, and phylogeny. (A) During methoxydotrophic growth, 3,4,5-trimethoxybenzoate (TMB) methyl-groups are transferred by an unknown mechanism to the central carbon metabolism of the methanogen. The methyl-group will be transferred onto HS-CoM and MCR will branch methyl-S-CoM to CoB-SH by a thiyl-radical based reaction catalyzed by its F₄₃₀ cofactor. The end products of the reaction are methane and the heterodisulfide made of HS-CoM and CoB-SH. (B) Purification profile on SDS-PAGE of MCR α, β and γ subunits from TMB-grown cells. (C) Phylogenetic tree of concatenated MCR generated with MegaX using the Maximum Likelihood method and JTT matrix-based model (see Materials and Methods). Orange and red backgrounds indicate thermophiles and hyperthermophiles, respectively. Structural information exists for the species with asterisks. Post-translational modifications (PTM) observed in the structures are shown: mH, N¹-methylhistidine; mR, 5(S)-methylarginine; mQ, 2(S)-methylglutamine; sG, thioglycine; mC, S-methylcysteine; dD, didehydroaspartate; hW, 6-hydroxytryptophan in M. formicicus and 7-hydroxytryptophan in ANME-1; oM, oxidized methionine. Growth substrates are also indicated (Ac, acetate; F, formate; MC, methylated compounds; Ar-O-CH₃, methoxylated compounds).