Glutamine—tRNA ligase

Glutamine—tRNA ligase
Identifiers
EC no.6.1.1.18
CAS no.9075-59-6
Databases
IntEnzIntEnz view
BRENDABRENDA entry
ExPASyNiceZyme view
KEGGKEGG entry
MetaCycmetabolic pathway
PRIAMprofile
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
Search
PMCarticles
PubMedarticles
NCBIproteins

Glutamine-tRNA ligase or glutaminyl-tRNA synthetase (GlnRS) is an aminoacyl-tRNA synthetase (aaRS or ARS), also called tRNA-ligase. is an enzyme that attaches glutamine amino acid onto its cognate tRNA.[1]

This enzyme participates in glutamate metabolism and aminoacyl-trna biosynthesis.

The human gene for glutaminyl-tRNA synthetase is QARS.

Catalyzed reaction

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A glutamine—tRNA ligase (EC 6.1.1.18) is an enzyme that catalyzes the chemical reaction

The cycle and mechanism of aminoacylation by tRNA synthetases.
ATP + L-glutamine + tRNAGln AMP + diphosphate + L-glutaminyl-tRNAGln

The 3 substrates of this enzyme are ATP, L-glutamine, and tRNA(Gln), whereas its 3 products are AMP, diphosphate, and L-glutaminyl-tRNA(Gln). The cycle of aminoacylation is shown in the figure for the aaRS cycle.

Nomenclature

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This enzyme belongs to the family of ligases, to be specific those forming carbon-oxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is L-glutamine:tRNAGln ligase (AMP-forming). Other names in use include:

  • glutaminyl-tRNA synthetase,
  • glutaminyl-transfer RNA synthetase,
  • glutaminyl-transfer ribonucleate synthetase,
  • glutamine-tRNA synthetase,
  • glutamine translase,
  • glutamate-tRNA ligase,
  • glutaminyl ribonucleic acid, and
  • GlnRS.

Evolution

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Although present in eukaryotes, glutaminyl-tRNA synthetase is absent from many prokaryotes, mitochondria, and chloroplasts, in which Gln-tRNAGln is formed by transamidation of the misacylated Glu-tRNAGln by the glutaminyl-tRNA synthase (glutamine-hydrolysing) enzyme.[2]

Aminoacyl tRNA synthetases are divided into two major classes based on their active site structure: class I and II.[2] Glutaminyl-tRNA synthetase belongs to the class-I aminoacyl-tRNA synthetase family.

Structure

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Starting at the N-terminus, the human glutaminyl-tRNA synthetase contains a two tandem non-specific RNA binding regions, a catalytic domain, and two tandem anti-codon binding domains in the C-terminus.[3]

The first crystal structure of a tRNA synthetase in complex with its cognate tRNA was that of tRNA-Gln:GlnRS, determined in 1989 (PDB accession code (1GSG). [4] This was also the first crystal structure of a non-viral protein:RNA complex.[5]

As of late 2024, over 38 structures have been solved for this class of enzymes.[6] Some of the PDB accession codes include 1EUQ, 1EUY, 1EXD, 1GSG, 1GTR, 1GTS, 1NYL, 1O0B, 1O0C, 1QRS, 1QRT, 1QRU, 1QTQ, 1ZJW, and 2HZ7. The E. coli glutaminyl-tRNA synethetase structure complexed with its cognate tRNA, tRNAGln is depicted in the figure (accession number 1EUG. [7]

Crystal structure of E. coli glutaminyl-tRNA synthetase complexed with a tRNA(Gln) mutant and an active-site inhibitor (Accession number: 1EUG). The tRNA is depicted in green and the glutaminyl-tRNA synthetase is in orange.

References

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  1. ^ Perona JJ (2013). "Glutaminyl-tRNA Synthetases". Madame Curie Bioscience Database [Internet]. Landes Bioscience. Retrieved 2024-07-31.
  2. ^ a b Rubio Gomez MA, Ibba M (August 2020). "Aminoacyl-tRNA synthetases". RNA. 26 (8): 910–936. doi:10.1261/rna.071720.119. PMC 7373986. PMID 32303649.
  3. ^ "Glutamine--tRNA ligase". InterPro. P47897.
  4. ^ Rould MA, Perona JJ, Söll D, Steitz TA (December 1989). "Structure of E. coli glutaminyl-tRNA synthetase complexed with tRNA(Gln) and ATP at 2.8 A resolution". Science. 246 (4934): 1135–1142. doi:10.1126/science.2479982. PMID 2479982.
  5. ^ PDB Statistics: Protein-Nucleic Acid Complexes Released Per Year Protein Data Bank
  6. ^ "InterPro". www.ebi.ac.uk. Retrieved 2024-08-02.
  7. ^ Sherlin LD, Bullock TL, Newberry KJ, Lipman RS, Hou YM, Beijer B, et al. (2000-06-01). "Influence of transfer RNA tertiary structure on aminoacylation efficiency by glutaminyl and cysteinyl-tRNA synthetases". Journal of molecular biology. 299 (2): 431–446. doi:10.1006/jmbi.2000.3749. ISSN 1089-8638. PMID 10860750.