PMID:6450203

Citation	Grove, G and Marzluf, GA (1981) Identification of the product of the major regulatory gene of the nitrogen control circuit of Neurospora crassa as a nuclear DNA-binding protein. J. Biol. Chem. 256:463-70
Abstract	The nitrogen regulatory circuit of Neurospora crassa contains an entire set of unlinked structural genes which specify nitrogen catabolic enzymes. These genes are controlled as a group by a major regulatory gene, designated nit-2, which "turns on" their expression in a positive fashion. Moreover, expression of these same structural genes is repressed when the cells contain sufficient nitrogen; the active repressor metabolite has been identified as glutamine. It has been suggested that the nit-2 gene product is a protein which binds at a recognition sequence near each nitrogen-related structural gene to activate their expression. We have directly examined the nuclear proteins of Neurospora in order to attempt to detect th postulated nit-2 regulatory protein. Nonhistone nuclear proteins were isolated, labeled in vitro, and applied to DNA-cellulose and subsequently specifically eluted with glutamine. A single protein, whose molecular weight is approximately 22,000, was eluted from DNA-cellulose by glutamine but not by asparagine. This same protein was greatly reduced in quantity in the nonhistone proteins isolated from two nit-2 mutants; a third nit-2 mutant has a normal amount of this nuclear protein but it displays a slightly higher electrophoretic mobility than found in wild type. Finally, a revertant of a nit-2 mutant possesses approximatley 20 times as much of this protein as does the parental nit-2 mutant, an amount essentially equivalent to that found in wild type. The results suggest that the nit-2 control gene encodes this DNA-binding protein, which is postulated to play a major role in regulating expression of the structural genes of the nitrogen control circuit of Neurospora.
Links	PubMed
Keywords	Carrier Proteins/genetics; Carrier Proteins/isolation & purification; Cell Nucleus/metabolism; Chromatography, Affinity; DNA/genetics; DNA/isolation & purification; DNA-Binding Proteins; Genes, Regulator; Glutamine; Molecular Weight; Mutation; Neurospora/metabolism; Neurospora crassa/genetics; Neurospora crassa/metabolism; Nitrogen/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
NEUCR:NIT2		GO:0044270: cellular nitrogen compound catabolic process	ECO:0000314:		P		Figure 6: nit-2 protein in N.crassa (strain 74-0R23-1A)component of non-histone chromosomal protein is 21,900 daltons.	complete CACAO 9609

References

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