Glutaminyl-tRNA synthase (glutamine-hydrolysing)

Glu-tRNA amidotransferase or glutaminyl-tRNA synthase (glutamine-hydrolysing) enzyme (EC 6.3.5.7) is an amidotransferase that catalyzes the conversion of the non-cognate amino acid glutamyl-tRNA to the cognate glutaminyl-tRNA. It catalyzes the reaction:

ATP + glutamyl-tRNA + L-glutamine

\rightleftharpoons

ADP + phosphate + glutaminyl-tRNA + L-glutamate

This enzyme belongs to the family of ligases, specifically those forming carbon-nitrogen bonds carbon-nitrogen ligases with glutamine as amido-N-donor. The systematic name of this enzyme class is glutamyl-tRNA:L-glutamine amido-ligase (ADP-forming). This enzyme participates in glutamate metabolism and alanine and aspartate metabolism.

Function and evolutionary significance

Most bacterial and all archaea genomes do not encode a glutaminyl-tRNA synthetase (GlnRS). Instead they first synthesize the attachment of an amino acid on the tRNA by first attaching a non-cognate glutamate to the tRNA. Then these organisms use the amidotransferase: glutaminyl-tRNA synthase (glutamine-hydrolysing) (EC 6.3.5.7) enzyme to convert the glutamate attached to tRNA to glutamine.

References

^ Sheppard K, Yuan J, Hohn MJ, Jester B, Devine KM, Söll D (April 2008). "From one amino acid to another: tRNA-dependent amino acid biosynthesis". Nucleic Acids Research. 36 (6): 1813–1825. doi:10.1093/nar/gkn015. PMC 2330236. PMID 18252769.

v t e Enzymes: CO CS and CN ligases (EC 6.1-6.3)
6.1: Carbon-Oxygen	Aminoacyl tRNA synthetase Alanine Arginine Asparagine Aspartate Cysteine D-alanine—poly(phosphoribitol) ligase Glutamate Glutamine Glycine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryptophan Tyrosine Valine
6.2: Carbon-Sulfur	Succinyl coenzyme A synthetase Acetyl—CoA synthetase Long-chain-fatty-acid—CoA ligase
6.3: Carbon-Nitrogen	Glutamine synthetase Ubiquitin ligase Cullin Von Hippel–Lindau tumor suppressor UBE3A Mdm2 Anaphase-promoting complex UBR1 Glutathione synthetase CTP synthetase Adenylosuccinate synthase Argininosuccinate synthase Holocarboxylase synthetase GMP synthase Asparagine synthetase Carbamoyl phosphate synthetase I II Glutamate–cysteine ligase

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

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