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Aminoacyl-tRNA synthetases (EC 6.1.1.-) [1] are a group of enzymes which activate amino acids and transfer them to specific tRNA molecules as the first step in protein biosynthesis. In prokaryotic organisms there are at least twenty different types of aminoacyl-tRNA synthetases, one for each different amino acid. In eukaryotes there are generally two aminoacyl-tRNA synthetases for each different amino acid: one cytosolic form and a mitochondrial form. While all these enzymes have a common function, they are widely diverse in terms of subunit size and of quaternary structure.

A few years ago it was found [2] that several aminoacyl-tRNA synthetases share a region of similarity in their N-terminal section, in particular the consensus tetrapeptide His-Ile-Gly-His ('HIGH') is very well conserved. The 'HIGH' region has been shown [3] to be part of the adenylate binding site. The 'HIGH' signature has been found in the aminoacyl-tRNA synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan, and valine. These aminoacyl-tRNA synthetases are referred to as class-I synthetases [4,5,6] and seem to share the same tertiary structure based on a Rossmann fold.

In position 8 of the pattern His is present in all tRNA-synthetases of class-I except in some bacterial tryptophanyl-tRNA synthetases which have a Thr in that position.

November 1997 / Pattern and text revised.

PROSITE method (with tools and information) covered by this documentation:

AA_TRNA_LIGASE_I, PS00178; Aminoacyl-transfer RNA synthetases class-I signature  (PATTERN)

Consensus pattern: P-x(0,2)-[GSTAN]-[DENQGAPK]-x-[LIVMFP]-[HT]-[LIVMYAC]-G-[HNTG]-[LIVMFYSTAGPC] Sequences known to belong to this class detected by the pattern: ALL, except for Cys-tRNA ligases and some other sequences Other sequence(s) detected in Swiss-Prot: 57.

• Retrieve an alignment of Swiss-Prot true positive hits:   Clustal format, color, condensed view  / Clustal format, color  / Clustal format, plain text  / Fasta format • Retrieve the sequence logo from the alignment • Taxonomic tree view of all Swiss-Prot/TrEMBL entries matching PS00178 • Retrieve a list of all Swiss-Prot/TrEMBL entries matching PS00178 • Scan Swiss-Prot/TrEMBL entries against PS00178 • view ligand binding statistics

Matching PDB structures: 1BS2 1D2R 1EUQ 1EUY ... [ALL]

1	Authors	Schimmel P.
	Title	Aminoacyl tRNA synthetases: general scheme of structure-function relationships in the polypeptides and recognition of transfer RNAs.
	Source	Annu. Rev. Biochem. 56:125-158(1987).
	PubMed ID	3304131
	DOI	10.1146/annurev.bi.56.070187.001013

2	Authors	Webster T., Tsai H., Kula M., Mackie G.A., Schimmel P.
	Title	Specific sequence homology and three-dimensional structure of an aminoacyl transfer RNA synthetase.
	Source	Science 226:1315-1317(1984).
	PubMed ID	6390679

3	Authors	Brick P., Bhat T.N., Blow D.M.
	Title	Structure of tyrosyl-tRNA synthetase refined at 2.3 A resolution. Interaction of the enzyme with the tyrosyl adenylate intermediate.
	Source	J. Mol. Biol. 208:83-98(1989).
	PubMed ID	2504923

4	Authors	Delarue M., Moras D.
	Title	The aminoacyl-tRNA synthetase family: modules at work.
	Source	BioEssays 15:675-687(1993).
	PubMed ID	8274143

5	Authors	Schimmel P.
	Title	Classes of aminoacyl-tRNA synthetases and the establishment of the genetic code.
	Source	Trends Biochem. Sci. 16:1-3(1991).
	PubMed ID	2053131

6	Authors	Nagel G.M., Doolittle R.F.
	Title	Evolution and relatedness in two aminoacyl-tRNA synthetase families.
	Source	Proc. Natl. Acad. Sci. U.S.A. 88:8121-8125(1991).
	PubMed ID	1896459

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