title: A Neurospora crassa mutant altered in the regulation of L-amino acid oxidase.
abstract: 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;MSOR 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 MSOR 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 MSOR mutation is epistatic to nit-2 since the nit2;MSOR double mutant regulated the L-amino acid oxidase in the same way as the MSOR single mutant.
authors.affiliation: Departamento de Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México DF 04510, Mexico.
authors.forename: Jorge
authors.initials: J
authors.lastname: Calderón
authors.affiliation: Departamento de Ecología Molecular, Centro de Investigación sobre Fijación de Nitrógeno UNAM, Apartado Postal 565-A, Cuernavaca, Mor., Mexico.
authors.forename: Leticia
authors.initials: L
authors.lastname: Olvera
authors.affiliation: Departamento de Ecología Molecular, Centro de Investigación sobre Fijación de Nitrógeno UNAM, Apartado Postal 565-A, Cuernavaca, Mor., Mexico.
authors.forename: Luz María
authors.initials: LM
authors.lastname: Martínez
authors.affiliation: Departamento de Genética Molecular, Centro de Investigación sobre Fijación de Nitrógeno UNAM, Apartado Postal 565-A, Cuernavaca, Mor., Mexico.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Dávila
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D005816:Genetic Complementation Test; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D050830:L-Amino Acid Oxidase; D009154:Mutation / Q000235:genetics; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics / Q000378:metabolism; D000637:Transaminases / Q000378:metabolism
chemical_list: D018698:Glutamic Acid; D000594:Amino Acid Oxidoreductases; D050830:L-Amino Acid Oxidase; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D000637:Transaminases; C020656:glutamine-pyruvate aminotransferase; D005974:Glutamate-Ammonia Ligase