Calderón J, Olvera L, Martínez LM, Dávila G. A Neurospora crassa mutant altered in the regulation of L-amino acid oxidase.
MICROBIOLOGY (READING, ENGLAND) 1997;
143 ( Pt 6):1969-1974. [PMID:
9202472 DOI:
10.1099/00221287-143-6-1969]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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.
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