tRNA (guanine-N-7) methyltransferase, Trmb type (IPR003358)

Short name: tRNA_(Gua-N-7)_MeTrfase_Trmb

Overlapping homologous superfamilies

Family relationships


This entry represents tRNA (guanine-N-7) methyltransferase (EC:, which catalyses the formation of N(7)-methylguanine at position 46 (m7G46) in tRNA. Capping of the pre-mRNA 5' end by addition a monomethylated guanosine cap (m(7)G) is an essential and the earliest modification in the biogenesis of mRNA [PMID: 17949828]. The reaction is catalysed by three enzymes: triphosphatase, guanylyltransferase, and tRNA (guanine-N-7) methyltransferase [PMID: 12403464, PMID: 18412263]. This entry includes Bacillus subtilis TrmB, which contains a a unique variant of the Rossmann-fold methyltransferase (RFM) structure, with the N-terminal helix folded on the opposite site of the catalytic domain [PMID: 16600901].

Methyltransferases (EC 2.1.1.-) constitute an important class of enzymes present in every life form. They transfer a methyl group most frequently from S-adenosyl L-methionine (SAM or AdoMet) to a nucleophilic acceptor such as oxygen leading to S-adenosyl-L-homocysteine (AdoHcy) and a methylated molecule [PMID: 16225687, PMID: 21858014, PMID: 12826405]. All these enzymes have in common a conserved region of about 130 amino acid residues that allow them to bind SAM [PMID: 7897657]. The substrates that are methylated by these enzymes cover virtually every kind of biomolecules ranging from small molecules, to lipids, proteins and nucleic acids [PMID: 16225687, PMID: 21858014, PMID: 7897657]. Methyltransferase are therefore involved in many essential cellular processes including biosynthesis, signal transduction, protein repair, chromatin regulation and gene silencing [PMID: 16225687, PMID: 21858014, PMID: 12826405]. More than 230 families of methyltransferases have been described so far, of which more than 220 use SAM as the methyl donor.

GO terms

Biological Process

GO:0006400 tRNA modification

Molecular Function

GO:0008176 tRNA (guanine-N7-)-methyltransferase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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