Family

Tyrosine-tRNA ligase, bacterial-type (IPR024088)

Short name: Tyr-tRNA-ligase_bac-type

Family relationships

Description

Tyrosine-tRNA ligases (TyrRS; also known as Tyrosyl-tRNA synthetases) (EC:6.1.1.1) are widely distributed, being found in archaea, bacteria and eukaryotes. TyrRS is a homodimer which attaches Tyr to the appropriate tRNA. TyrRS is a class I tRNA synthetases, so it aminoacylates the 2'-OH of the nucleotide at the 3' end of the tRNA. The core domain is based on the Rossman fold and is responsible for the ATP-dependent formation of the enzyme bound aminoacyl-adenylate. It contains the class I characteristic 'HIGH' and 'KMSKS' motifs, which are involved in ATP binding. Studies have shown that the 'KMSKS' motif plays a role in the initial binding of tRNA(Tyr) to tyrosine-tRNA ligase [PMID: 10630994].

Two main groups can be distinguished among tyrosine-tRNA ligases: one group contains bacterial and organellar eukaryotic proteins and the other archaeal and cytosolic eukaryotic proteins. This entry represents the bacterial and organellar eukaryotic tyrosine-tRNA ligases.

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 [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 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 [PMID: 10447505].

The class Ia aminoacyl-tRNA synthetases consist of the isoleucyl, methionyl, valyl, leucyl, cysteinyl, and arginyl-tRNA synthetases; the class Ib include the glutamyl and glutaminyl-tRNA synthetases, and the class Ic are the tyrosyl and tryptophanyl-tRNA synthetases [PMID: 11590011].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004831 tyrosine-tRNA ligase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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