1h1c
HISTIDINOL-PHOSPHATE AMINOTRANSFERASE (HISC) FROM THERMOTOGA MARITIMA
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OverviewOverview
In histidine biosynthesis, histidinol-phosphate aminotransferase catalyzes the transfer of the amino group from glutamate to imidazole acetol-phosphate producing 2-oxoglutarate and histidinol phosphate. In some organisms such as the hyperthermophile Thermotoga maritima, specific tyrosine and aromatic amino acid transaminases have not been identified to date, suggesting an additional role for histidinol-phosphate aminotransferase in other transamination reactions generating aromatic amino acids. To gain insight into the specific function of this transaminase, we have determined its crystal structure in the absence of any ligand except phosphate, in the presence of covalently bound pyridoxal 5'-phosphate, of the coenzyme histidinol phosphate adduct, and of pyridoxamine 5'-phosphate. The enzyme accepts histidinol phosphate, tyrosine, tryptophan, and phenylalanine, but not histidine, as substrates. The structures provide a model of how these different substrates could be accommodated by histidinol-phosphate aminotransferase. Some of the structural features of the enzyme are more preserved between the T. maritima enzyme and a related threonine-phosphate decarboxylase from S. typhimurium than with histidinol-phosphate aminotransferases from different organisms.
About this StructureAbout this Structure
1H1C is a Single protein structure of sequence from Thermotoga maritima with as ligand. Active as Histidinol-phosphate transaminase, with EC number 2.6.1.9 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Structural studies of the catalytic reaction pathway of a hyperthermophilic histidinol-phosphate aminotransferase., Fernandez FJ, Vega MC, Lehmann F, Sandmeier E, Gehring H, Christen P, Wilmanns M, J Biol Chem. 2004 May 14;279(20):21478-88. Epub 2004 Mar 8. PMID:15007066
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