Nitrogen regulation of amino acid utilization by Neurospora crassa

Abstract

The production of an extracellular deaminase activity involved with the utilization of amino acids as sole sources of nitrogen is pnder the control of the nit-2 locus of Neurospora crassa. This locus is the sole major nitrogen regulatory locus described for N. crassa and is believed to encode a-positive effector required for induction of activities involved with the utilization of alternate nitrogen sources. Production of deaminase activity requires the lifting of nitrogen metabolite repression, the presence of a functional nit-2 gene product, and specific induction by amino acids. Additional parameters-of enzyme production are described.

Exploring Regulation Genes Involved in the Expression of L-Amino Acid Oxidase in Pseudoalteromonas sp. Rf-1

“…It was also reported that LAAO activity in N . crassa can be induced through addition of L-amino acids to nitrogen-starved cultures as well as addition of protein synthesis inhibitors or D-amino acids [ 12 , 13 ]. LAAO expression was regulated by NIT2 and the nmr gene product at transcriptional level [ 14 ].…”

Regulation of amino acid utilization in Neurospora crassa: effect of nmr-1 and ms-5 mutations

“…The pmn; pmb; pmg strain of N. crassa produces an extracellular deaminase in response to nitrogen limitation plus the presence of an amino acid (12). Production of this enzyme is prevented by glutamine-mediated nitrogen metabolite repression (10,11). The details of the mechanism by which amino acid utilization occurs in this transport-defective strain are not fully known, but it is believed that the degradation of the amino acid to its keto acid and ammonium ion components provides the necessary nitrogen (10,11).…”

“…Production of this enzyme is prevented by glutamine-mediated nitrogen metabolite repression (10,11). The details of the mechanism by which amino acid utilization occurs in this transport-defective strain are not fully known, but it is believed that the degradation of the amino acid to its keto acid and ammonium ion components provides the necessary nitrogen (10,11). Transport of these components by their respective transport systems allows for potential internal reconstitution of the amino acid molecule.…”

“…Transport of these components by their respective transport systems allows for potential internal reconstitution of the amino acid molecule. Glutamine is unusual in that, in addition to the deaminasemediated route of entry, it appears to have an additional mechanism for external degradation and internal resynthesis; thus, it is able to serve as a repressor in a strain that cannot transport it (11).…”

“…3). Typically, enzyme production does not occur in the absence of amino acid, even under nitrogen-limiting conditions (11). To investigate the effect of the nmr-J and ms-S mutations with respect to inducer requirement, we examined the ability of the pmn; pmb; pmg; nmr-J and pmn; pmb; pmg; ms-5 strains to produce extracellular deaminase in the presence of ammonium chloride (Fig.…”