Methionyl-tRNA synthetase, beta subunit, C-terminal (IPR004495)

Short name: Met-tRNA-synth_bsu_C

Overlapping homologous superfamilies

Domain relationships

  • tRNA-binding domain (IPR002547)
    • Methionyl-tRNA synthetase, beta subunit, C-terminal (IPR004495)


The aminoacyl-tRNA synthetases (also known as aminoacyl-tRNA ligases) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction [PMID: 10704480,PMID: 12458790]. These proteins differ widely in size and oligomeric state, and have limited sequence homology [PMID: 2203971]. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric [PMID: 10673435]. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices [PMID: 8364025], and are mostly dimeric or multimeric, containing at least three conserved regions [PMID: 8274143, PMID: 2053131, PMID: 1852601]. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan, valine, and some lysine synthetases (non-eukaryotic group) belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, phenylalanine, proline, serine, threonine, and some lysine synthetases (non-archaeal group), belong to class-II synthetases. Based on their mode of binding to the tRNA acceptor stem, both classes of tRNA synthetases have been subdivided into three subclasses, designated 1a, 1b, 1c and 2a, 2b, 2c [PMID: 10447505].

The methionyl-tRNA synthetase (MetG) (EC: is a class I amino acyl-tRNA ligase. This family describes a region of the methionyl-tRNA synthetase that is present at the C terminus of MetG in some species (Escherichia coli, Bacillus subtilis, Thermotoga maritima, Methanothermobacter thermautotrophicus (Methanobacterium thermoformicicum), and as a separate beta chain in Aquifex aeolicus [PMID: 10369686, PMID: 12481025]. It is absent in a number of other species (e.g. Mycoplasma genitalium, Mycobacterium tuberculosis), while Pyrococcus horikoshii has both a full length MetG and a second protein homologous to the beta chain only. This domain has general tRNA binding properties. The functional unit of MetG and Aquifex aeolicus Trbp111 is a homodimer, this domain acts as the dimerization domain [PMID: 12390027, PMID: 11101501].

GO terms

Biological Process

GO:0006431 methionyl-tRNA aminoacylation

Molecular Function

GO:0005524 ATP binding
GO:0004825 methionine-tRNA ligase activity
GO:0000166 nucleotide binding

Cellular Component

No terms assigned in this category.

Contributing signatures

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