Glutaminyl-tRNA synthase (glutamine-hydrolysing)

Glu-tRNA^Gln 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^Gln to the cognate glutaminyl-tRNA^Gln..^[1] It catalyzes the reaction:

ATP + glutamyl-tRNA^Gln + L-glutamine ${\displaystyle \rightleftharpoons }$ ADP + phosphate + glutaminyl-tRNA^Gln + L-glutamate

Glutaminyl-tRNA synthase (glutamine-hydrolyzing)
Identifiers
EC no.	6.3.5.7
CAS no.	52232-48-1
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

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^Gln: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).^[1] Instead they first synthesize the attachment of an amino acid on the tRNA^Gln 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^Gln to glutamine. ^[1]