title: Glutamate-1-semialdehyde aminotransferase from Sulfolobus solfataricus.
abstract: Glutamate-1-semialdehyde aminotransferase (GSA-AT) from the extremely thermophilic bacterium Sulfolobus solfataricus has been purified to homogeneity and characterized. GSA-AT is the last enzyme in the C5 pathway for the conversion of glutamate into the tetrapyrrole precursor delta-aminolaevulinate (ALA) in plants, algae and several bacteria. The active form of GSA-AT from S. solfataricus seems to be a homodimer with a molecular mass of 87 kDa. The absorption spectrum of the purified aminotransferase is indicative of the presence of pyridoxamine 5'-phosphate (PMP) cofactor, and the catalytic activity of the enzyme is further stimulated by addition of PMP. 3-Amino-2,3-dihydrobenzoic acid is an inhibitor of the aminotransferase activity. The N-terminal amino acid sequence of GSA-AT from S. solfataricus was found to share significant similarity with the eukaryotic and eubacterial enzymes. Evidence is provided that ALA synthesis in S. solfataricus follows the C5 pathway characteristic of plants, algae, cyanobacteria and many other bacteria.
authors.affiliation: Dipartimento di Chimica Organica e Biologica, Napoli, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Palmieri
authors.forename: M
authors.initials: M
authors.lastname: Di Palo
authors.forename: A
authors.initials: A
authors.lastname: Scaloni
authors.forename: S
authors.initials: S
authors.lastname: Orru
authors.forename: G
authors.initials: G
authors.lastname: Marino
authors.forename: G
authors.initials: G
authors.lastname: Sannia
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D000458:Cyanobacteria / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D001467:Hordeum / Q000201:enzymology; D019751:Intramolecular Transferases; D007535:Isomerases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D013053:Spectrophotometry; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D010446:Peptide Fragments; D007535:Isomerases; D019751:Intramolecular Transferases; C061049:glutamate-1-semialdehyde 2,1-aminomutase