Type: | Family | Name: | Glutamine-tRNA ligase, bacterial |
Description: | This entry represents bacterial glutamine-tRNA ligases.Glutamine-tRNA ligase () is a class Ic aminoacyl-tRNA ligase and shows several similarities with glutamine-tRNA ligase concerning structure and catalytic properties. It is an alpha2 dimer. Glutamine-tRNA ligase is a relatively rare ligase, found in the cytosolic compartment of eukaryotes, in Escherichia coliand a number of other Gram-negative bacteria, and in Deinococcus radiodurans. In contrast, the pathway to Gln-tRNA in mitochondria, Archaea, Gram-positive bacteria, and a number of other lineages is by misacylation with Glu followed by transamidation to correct the aminoacylation to Gln.The aminoacyl-tRNA synthetase (also known as aminoacyl-tRNA ligase) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology []. 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 []. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices [], and are mostly dimeric or multimeric, containing at least three conserved regions [, , ]. 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 and valine belong to class I synthetases. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine 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. | Short Name: | Gln_tRNA_ligase_bac |