Neurospora crassa mutant altered in the regulation of L-amino acid oxidase

• Published in: Microbiology (Society for General Microbiology) Vol. 143; no. 6; pp. 1969 - 1974
• Main Authors: Calderon, J, Olvera, L, Martinez, L.M, Davila, G
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.06.1997; Society for General Microbiology
• Subjects: Amino Acid Oxidoreductases - genetics; Amino Acid Oxidoreductases - metabolism; Biological and medical sciences; Cell Division - genetics; Cell Division - physiology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic - physiology; Genetic Complementation Test; Glutamate-Ammonia Ligase - metabolism; Glutamic Acid - metabolism; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; L-Amino Acid Oxidase; Microbiology; Mutation - genetics; Mycology; Neurospora crassa; Neurospora crassa - enzymology; Neurospora crassa - genetics; Neurospora crassa - isolation & purification; Nitrate Reductase; Nitrate Reductases - genetics; Nitrate Reductases - metabolism; plant biochemistry; plant breeding; plant genetics; plant physiology; Transaminases - metabolism; Fungi; Regulation(control); Enzyme; L-Amino-acid oxidase; Ascomycetes; Neurospora crassa; Oxidoreductases; Nitrogen; Gene expression; Metabolism; Thallophyta
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-143-6-1969

The isolation and characterization of a Neurospora crassa mutant altered in L-amino oxidase regulation is reported. The previously isolated gln-1bR8 strain, which only synthesizes the glutamine synthetase alpha monomer and lacks the beta monomer, was used as parental strain. A mutant derivative of strain was selected for its ability to grow on minimal medium in the presence of DL-methionine-SR-sulfoximine (MSO), an inhibitor of glutamine synthetase activity. This gln-1bR8; MSO(R) mutant overcame the inhibitory effect of MSO by increasing the activity of L-amino acid oxidase, an enzyme capable of degrading this compound. In contrast with the wild-type strain, the L-amino acid oxidase of the MSO mutant was resistant to glutamine repression; in fact, it was induced by this amino acid but repressed by ammonium. This mutant is different from other nitrogen regulatory N. crassa mutants reported and is only altered in the regulation of L-amino acid oxidase. The MSO(R) mutation is epistatic to nit-2 since the nit2; MSO(R) double mutant regulated the L-amino acid oxidase in the same way as the MSO(R) single mutant.