InterPro domain: IPR012676

The TGS domain is present in a number of enzymes, for example, in threonyl-tRNA synthetase (ThrRS), GTPase, and guanosine 3',5'-bis(diphosphate) 3'-pyrophosphohydrolase (SpoT) [ 1 ]. The TGS domain is also present at the amino terminus of the uridine kinase from the spirochaete Treponema pallidum (but not any other organism, including the related spirochaete Borrelia burgdorferi).

TGS is a small domain that consists of ~50 amino acid residues and is predicted to possess a predominantly beta-sheet structure. There is no direct information on the functions of the TGS domain, but its presence in two types of regulatory proteins (the GTPases and guanosine polyphosphate phosphohydrolases/synthetases) suggests a ligand (most likely nucleotide)-binding, regulatory role [ 2 ]. The TGS domain is possibly related to the ubiquitin-like and MoaD/ThiS superfamilies, and has some similarity to the alpha-L RNA-binding motif.

This superfamily represents TGS domain-containing proteins, as well as The C-terminal domain of bacterial and fungal YchF, a universally conserved GTPase whose function is unknown [ 2 ].

1. Evolution of aminoacyl-tRNA synthetases--analysis of unique domain architectures and phylogenetic trees reveals a complex history of horizontal gene transfer events. Genome Res. 9, 689-710
2. Crystal structure of the YchF protein reveals binding sites for GTP and nucleic acid. J. Bacteriol. 185, 4031-7