TrmE-type guanine nucleotide-binding domain (IPR031168)

Short name: G_TrmE

Overlapping homologous superfamilies

Domain relationships


The P-loop guanosine triphosphatases (GTPases) control a multitude of biological processes, ranging from cell division, cell cycling, and signal transduction, to ribosome assembly and protein synthesis. GTPases exert their control by interchanging between an inactive GDP-bound state and an active GTP-bound state, thereby acting as molecular switches. The common denominator of GTPases is the highly conserved guanine nucleotide-binding (G) domain that is responsible for binding and hydrolysis of guanine nucleotides.

TrmE (also called MnmE, ThdF or MSS1) contains a canonical G domain and is conserved in all three kingdoms of life. It is involved in the modification of uridine bases (U34) at the first anticodon (wobble) position of tRNAs decoding two-family box triplets. TrmE is organised as a multidomain protein consisting of an ~220-amino acid N-terminal domain, probably required for self-assembly, a middle GTPase domain, of about 160 residues, and an ~75-amino acid C-terminal domain, which contains a highly conserved CxGK motif. TrmE contains at least four of the five conserved nucleotide-binding motifs G1 (GxxxxGK[ST] or P- loop), G2 (T), G3 (DxxG) and G4 ([NT]KxD). The totally invariant alanine in the SA[KL] (G5) motif of Ras anGalph proteins is less well conserved [PMID: 11916378, PMID: 11092873, PMID: 12730230, PMID: 15616586, PMID: 17143896].

TrmE functions as a molecular switch GTPase, and apparently uses a conformational change associated with GTP hydrolysis to promote the tRNA modification reaction, in which the conserved cysteine in the C-terminal domain is thought to function as a catalytic residue. In bacteria that are able to survive in extremely low pH conditions, TrmE regulates glutamate-dependent acid resistance [PMID: 15522079].

This entry represents the TmrE-type G domain. The structure of the TrmE-type G domain consists of a a canonical Ras-like fold: central four-stranded beta-sheet flanked by five alpha-helices. It dimerises in a potassium-dependent manner [PMID: 15616586, PMID: 17143896].

Contributing signatures

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