A Cobalamin-Dependent Radical SAM Enzyme Catalyzes the Unique C_α -Methylation of Glutamine in Methyl-Coenzyme M Reductase.

ABSTRACT: Methyl-coenzyme M reductase, which is responsible for the production of the greenhouse gas methane during biological methane formation, carries several unique posttranslational amino acid modifications, including a 2-(S)-methylglutamine. The enzyme responsible for the C_α -methylation of this glutamine is not known. Herein, we identify and characterize a cobalamin-dependent radical SAM enzyme as the glutamine C-methyltransferase. The recombinant protein from Methanoculleus thermophilus binds cobalamin in a base-off, His-off conformation and contains a single [4Fe-4S] cluster. The cobalamin cofactor cycles between the methyl-cob(III)alamin, cob(II)alamin and cob(I)alamin states during catalysis and produces methylated substrate, 5'-deoxyadenosine and S-adenosyl-l-homocysteine in a

SUBMITTER: Gagsteiger J 

PROVIDER: S-EPMC9401015 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature