Disease relevance of hemL

• Increased HemA protein levels were also observed in heme-limited cells of a hemL mutant in two different E. coli backgrounds, suggesting that the observed regulation is conserved between E. coli and S. typhimurium [1].
• Cloning and sequence of the Salmonella typhimurium hemL gene and identification of the missing enzyme in hemL mutants as glutamate-1-semialdehyde aminotransferase [2].
• No sequence similarity was detected, at either the nucleic acid or the peptide level, with the Rhodobacter capsulatus or Bradyrhizobium japonicum hemA genes, which encode ALA synthase, or with the S. typhimurium hemL gene, which encodes glutamate-1-semialdehyde aminotransferase [3].
• Cloning, mapping and characterization of the Pseudomonas aeruginosa hemL gene [4].
• The gene from Xanthomonas campestris pv. phaseoli for glutamate 1-semialdehyde (GSA) aminomutase, which is involved in the C5 pathway for synthesis of delta-aminolevulinic acid (ALA), was cloned onto a multicopy plasmid, pUC18, by the complementation of an ALA-deficient mutant (hemL) of Escherichia coli [5].

High impact information on hemL

• 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].
• In the cyanobacterium Synechocystis sp. PCC 6803 and in the enterobacterium Escherichia coli delta-amino-levulinic acid (ALA) is formed from glutamyl-tRNA by the sequential action of two enzymes, glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase [7].
• Activity and spectroscopic properties of the Escherichia coli glutamate 1-semialdehyde aminotransferase and the putative active site mutant K265R [8].
• Nucleotide sequencing indicated that the gene that complemented AlaA- was identical to hemL which is located at 4 min on the E. coli chromosome and encodes glutamate 1-semialdehyde aminotransferase [9].
• Physical mapping showed that hemL mapped clockwise next to fhuB [10].

Biological context of hemL

• The S. typhimurium hemL gene was sequenced and determined to contain an open reading frame of 426 codons encoding a 45.3-kDa polypeptide [2].
• The hemL gene was mapped to the SpeI fragment Z and the DpnI fragment J1 of the P. aeruginosa chromosome corresponding approximately to min 0.3-0 [4].
• 9. One transcription start site was located 280 bp upstream of the translational start site of the hemL gene [4].
• Map positions and resulting phenotypes suggest that hemL may be identical with the earlier described porphyrin biosynthesis mutation popC [10].
• The gene that codes for GSAT was amplified from the cDNA library of Bacillus subtilis and overexpressed in Escherichia coli strain BL21(DE3) [11].

Associations of hemL with chemical compounds

• The presence of a gene for glutamate-1-semialdehyde aminotransferase suggests that Polytomella sp. uses the five-carbon pathway for synthesis of the heme precursor 5-aminolevulinic acid [12].

Other interactions of hemL

• Functional complementation of Escherichia coli mutant strains was used to isolate cDNAs encoding three heme biosynthetic enzymes, glutamate-1-semialdehyde aminotransferase, protoporphyrinogen IX oxidase, and ferrochelatase [12].

Analytical, diagnostic and therapeutic context of hemL

• Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of the glutamate-1-semialdehyde aminotransferase from Bacillus subtilis [11].

References