Functional analysis of all aminotransferase proteins inferred from the genome sequence of Corynebacterium glutamicum.
Twenty putative aminotransferase (AT) proteins of Corynebacterium glutamicum, or rather pyridoxal-5'-phosphate (PLP)-dependent enzymes, were isolated and assayed among others with L-glutamate, L-aspartate, and L-alanine as amino donors and a number of 2-oxo-acids as amino acceptors. One outstanding AT identified is AlaT, which has a broad amino donor specificity utilizing (in the order of preference) L-glutamate > 2-aminobutyrate > L-aspartate with pyruvate as acceptor. Another AT is AvtA, which utilizes L-alanine to aminate 2-oxo-isovalerate, the L-valine precursor, and 2-oxo-butyrate. A second AT active with the L-valine precursor and that of the other two branched-chain amino acids, too, is IlvE, and both enzyme activities overlap partially in vivo, as demonstrated by the analysis of deletion mutants. Also identified was AroT, the aromatic AT, and this and IlvE were shown to have comparable activities with phenylpyruvate, thus demonstrating the relevance of both ATs for L-phenylalanine synthesis. We also assessed the activity of two PLP-containing cysteine desulfurases, supplying a persulfide intermediate. One of them is SufS, which assists in the sulfur transfer pathway for the Fe-S cluster assembly. Together with the identification of further ATs and the additional analysis of deletion mutants, this results in an overview of the ATs within an organism that may not have been achieved thus far.
Marienhagen
Jan
J
Institute of Biotechnology, Research Centre Juelich, Germany.
Kennerknecht
Nicole
N
Sahm
Hermann
H
Eggeling
Lothar
L
D000409:Alanine / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D002087:Butyrates / Q000378:metabolism; D013437:Carbon-Sulfur Lyases / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics*; D017353:Gene Deletion; D018698:Glutamic Acid / Q000378:metabolism; D045782:Hemiterpenes; D007651:Keto Acids / Q000378:metabolism; D010667:Phenylpyruvic Acids / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D013379:Substrate Specificity; D000637:Transaminases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*
D001426:Bacterial Proteins; D002087:Butyrates; D045782:Hemiterpenes; D007651:Keto Acids; D010667:Phenylpyruvic Acids; C016211:alpha-keto-beta-methylvaleric acid; D001224:Aspartic Acid; D018698:Glutamic Acid; C005087:alpha-ketobutyric acid; C001505:alpha-ketoisovalerate; C013082:alpha-ketoisocaproic acid; D019289:Pyruvic Acid; D000637:Transaminases; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D000409:Alanine; C031606:phenylpyruvic acid