Disease relevance of L-Glutamate 1-semialdehyde

• Spectral kinetics of glutamate-1-semialdehyde aminomutase of Synechococcus [1].
• The three dimers are related by an approximate 3-fold screw axis with a translational component of 18 A. The monomer fold is that of a typical representative of subgroup 2 aminotransferases and very similar to those described for dialkylglycine decarboxylase from Pseudomonas cepacia and glutamate-1-semialdehyde aminomutase from Synechococcus [2].
• All three enzymes were separated from extracts of the unicellular cyanobacterium Synechocystis sp. PCC 6803, and two of them, glutamyl-tRNA synthetase and GSA aminotransferase, were partially characterized [3].

High impact information on L-Glutamate 1-semialdehyde

• An exception is the reduction of glutamyl-tRNA to glutamate-1-semialdehyde by the enzyme glutamyl-tRNA reductase [4].
• To protect the highly reactive reaction intermediate glutamate-1-semialdehyde (GSA), a tight complex between these two enzymes was proposed based on their solved crystal structures [5].
• A GSA aminotransferase gene, designated gsa1, was isolated and appears to be one of two gsa genes in the soybean genome. gsa1 mRNA accumulated to high levels in leaves and nodules, but not in uninfected roots as discerned with a gsa1-specific probe [6].
• The purified glutamate-1-semialdehyde aminotransferase successfully reconstitutes the whole C5-pathway in vitro from glutamate in the presence of purified glutamyl-tRNA synthetase, glutamyl-tRNA reductase, Mg2+, ATP, NADPH, tRNA, and pyridoxal 5'-phosphate [7].
• delta-Aminolevulinic acid (ALA), the universal biosynthetic precursor of tetrapyrrole pigments, is synthesized from glutamate in plants, algae, and many bacteria via a three-step process that begins with activation by ligation of glutamate to tRNA(Glu), followed by reduction to glutamate-1-semialdehyde (GSA) and conversion of GSA to ALA [8].

Biological context of L-Glutamate 1-semialdehyde

• The surroundings of the rrn operon and the contiguous glutamate-1-semialdehyde aminotransferase gene appear hot spots for recombination [9].

Associations of L-Glutamate 1-semialdehyde with other chemical compounds

• The predicted structure was used to propose a detailed biochemical mechanism for the GTR, involving Mg catalyzed thioester formation and reduction by NADPH to glutamate-1-semialdehyde [10].
• Formation of the universal tetrapyrrole precursor, delta-aminolevulinic acid (ALA), from glutamate via the five-carbon pathway requires three enzymes: glutamyl-tRNA synthetase, glutamyl-tRNA reductase, and glutamate-1-semialdehyde (GSA) aminotransferase [3].
• Homology of 1-aminocyclopropane-1-carboxylate synthase, 8-amino-7-oxononanoate synthase, 2-amino-6-caprolactam racemase, 2,2-dialkylglycine decarboxylase, glutamate-1-semialdehyde 2,1-aminomutase and isopenicillin-N-epimerase with aminotransferases [11].

Gene context of L-Glutamate 1-semialdehyde

• In the first step, glutamyl-tRNA reductase (GluTR), converts glutamate of glutamyl-tRNA to glutamate 1-semialdehyde (GSA) which is rearranged to ALA by glutamate 1-semialdehyde-2,1-aminomutase (GSA-A) in the second step [12].
• Neither glutamyl-tRNA synthetase nor GSA aminotransferase activity was affected by hemin concentrations up to 10 and 30 microM, respectively, and neither activity was affected by protochlorophyllide concentrations up to 2 microM [3].
• Glutamyl-tRNA reductase next catalyzes reduction of the activated glutamate to glutamate-1-semialdehyde (GSA), which is then converted to ALA by GSA aminotransferase [13].

Analytical, diagnostic and therapeutic context of L-Glutamate 1-semialdehyde

• The three-dimensional structure of glutamate-1-semialdehyde aminomutase (EC 5.4.3.8), an alpha2-dimeric enzyme from Synechococcus, has been determined by x-ray crystallography using heavy atom derivative phasing [14].
• The apparent native molecular masses of glutamyl-tRNA synthetase and GSA aminotransferase were determined by gel filtration chromatography to be 63 and 98 kDa, respectively [3].

References