Cobalamin-independent methionine synthase MetE, C-terminal/archaeal (IPR002629)

Short name: Met_Synth_C/arc

Overlapping homologous superfamilies


Domain relationships



Methionine synthases catalyse the the final step of methionine biosynthesis. Two apparently unrelated families of proteins catalyse this step: cobalamin-dependent methionine synthase, which catalyses the transfer of a methyl group from N5-methyltetrahydrofolate to L-homocysteine and requires cobalamin as a cofactor (MetH; 5-methyltetrahydrofolate:L-homocysteine S-methyltransferase; EC: and cobalamin-independent methionine synthase, which catalyses the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine without using an intermediate methyl carrier (MetE; 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase; EC: These enzymes display no detectable sequence homology between them, but both require zinc for activation and binding to L-homocysteine. Organisms that cannot obtain cobalamin (vitamin B12) encode only the cobalamin-independent enzyme. Escherichia coli and many other bacteria express both enzymes [PMID: 1339288]. Mammals utilise only cobalamin-dependent methionine synthase, while plants and yeasts utilise only the cobalamin-independent enzyme.

The N-terminal half and C-terminal half of MetE in E. coli show some sequence similarity, indicating that the metE gene has evolved from an ancestral metE gene by duplication [PMID: 1339288]. This entry represents a the C-terminal domain of cobalamin-independent methionine synthase (MetE) from bacteria and plants. It also includes archaeal proteins where this domain corresponds to the entire length of the protein [PMID: 10469143].

GO terms

Biological Process

GO:0009086 methionine biosynthetic process

Molecular Function

GO:0003871 5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase activity
GO:0008270 zinc ion binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.