Glutamine–tRNA ligase, also called glutaminyl-tRNA synthetase 1, is an enzyme that in humans is encoded by the QARS1 gene (previously QARS). More broadly, Glutamate–tRNA ligase (EC 6.1.1.18) can also refer to the type of enzyme activity that the QARS1 protein performs, namely catalyzing the attachment of the amino acid glutamine to transfer RNA using ATP.
Function
Aminoacyl-tRNA synthetases catalyze the aminoacylation of tRNA by their cognate amino acid. Because of their central role in linking amino acids with nucleotide triplets contained in tRNAs, aminoacyl-tRNA synthetases are thought to be among the first proteins that appeared in evolution. In metazoans, 9 aminoacyl-tRNA synthetases specific for glutamine (gln), glutamic acid (glu), and 7 other amino acids are associated within a multienzyme complex. Although present in eukaryotes, glutaminyl-tRNA synthetase (QARS) is absent from many prokaryotes, mitochondria, and chloroplasts, in which Gln-tRNA(Gln) is formed by transamidation of the misacylated Glu-tRNA(Gln). Glutaminyl-tRNA synthetase belongs to the class-I aminoacyl-tRNA synthetase family. Almost all eukaryotic GlnRS enzymes possess a YqeY domain at the N-terminus, which affects affinity for the tRNA; in some bacterial species, such as Deinococcus radiodurans, YqeY is present as a C-terminal domain with similar function.
Medical significance Pathogenic (compound heterozygous) mutations in QARS1 have been associated with a brain development disorder leading to an unusually small head and brain (microcephaly) among other symptoms called progressive microcephaly with seizures and cerebral and cerebellar atrophy (MSCCA).
Interactions
QARS1 has been shown to interact with RARS1.
References
Further reading