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Overview

Glutaminyl-tRNA synthetase or GlnRS is a class 1 tRNA synthetase that requires tRNA binding for adenylate synthesis, which suggests that the large substrate could be required to form the active site structure. ^[1] Genetic evidence shows that induced fit conformational changes are a big part in the mechanism of GlnRS. ^[1] Glutaminyl-tRNA synthetase is an enzyme who's function is to catalyze the transfer of the amino acid glutamine to the A76 hydroxyl group of tRNA^Gln. ^[1] Glutaminyl-tRNA synthetase was highly expressed in the developing of unborn-baby related, human brains in many cell types. ^[2]

Structure

The crystal structure of ligand-free E. coli glutaminyl-tRNA synthetase at 2.4 A shows substrate binding is needed to construct a catalytically proficient active site. ^[1] Five hundred and twenty-one of the five hundred and thirty-three amino acids were able to be built into the electron density maps. ^[1] The backbone atoms of 94 amino acid residues, could be superimposed on their counterparts showing similarities close to each other. ^[1] When superimposed there were few differences the unligand enzyme and the tRNA-bound enzyme.^[1] One of the amino acids in the of the dinucleotide fold adopts a new arrangement in the unligand enzyme. ^[1] Also, two amino acids in different surface loops in C-terminal beta barrel regions are fully disordered, just like the surface loop compromising amino acids. ^[1]

Mutations

Mutations in the coding of glutaminyl-tRNA synthetase can cause seizures especially in infants. ^[2] The mutations in the coding can cause progressive microcephaly and the tissue of the brain to waste away in several different regions including the cerebellar vermis, cerebral cortex, and the cerebellar hemispheres. ^[2] Progressive microcephaly is a condition that involves mutations in gene coding of brain survival. ^[2] Seizures are severe but not very common compared to the other disorders. ^[2] Glutaminyl-tRNA synthetase is important during the brain development stages. ^[2] The cerebral cortex and the cerebellar vermis are the primarly affected areas with a mutation in the coding of glutaminyl-tRNA synthetase and is a big distinction between it and other coding mutations, for example PCH, which is a caused by mutations but with it the cerebellum and the brain stem are mostly affected. ^[2]