Glutamate synthase levels in Neurospora crassa mutants altered with respect to nitrogen metabolism.
AUTOR(ES)
Dunn-Coleman, N S
RESUMO
Glutamate synthase catalyzes glutamate formation from 2-oxoglutarate plus glutamine and plays an essential role when glutamate biosynthesis by glutamate dehydrogenase is not possible. Glutamate synthase activity has been determined in a number of Neurospora crassa mutant strains with various defects in nitrogen metabolism. Of particular interest were two mutants phenotypically mute except in an am (biosynthetic nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase deficient, glutamate requiring) background. These mutants, i and en-am, are so-called enhancers of am; they have been redesignated herein as en(am)-1 and en(am)-2, respectively. Although glutamate synthase levels in en(am)-1 were essentially wild type, the en(am)-2 strain was devoid of glutamate synthase activity under all conditions examined, suggesting that en(am)-2 may be the structural locus for glutamate synthase. Regulation of glutamate synthase occurred to some extent, presumably in response to glutamate requirements. Glutamate starvation, as in am mutants, led to enhanced activity. In contrast, glutamine limitation, as in gln-1 mutants, depressed glutamate synthase levels.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=369655Documentos Relacionados
- Production of nitrous oxide from nitrite in Klebsiella pneumoniae: mutants altered in nitrogen metabolism.
- Salmonella typhimurium Mutants with Altered Glutamate Dehydrogenase and Glutamate Synthase Activities
- Escherichia coli mutants with altered ribosomal ribonucleic acid metabolism.
- Mutants Affecting Thymidine Metabolism in Neurospora crassa
- Nitrogen Source Regulates Glutamate Dehydrogenase NADP Synthesis in Neurospora crassa