Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The areA gene of filamentous fungi encodes a positive-acting transcriptional factor required for the expression of genes involved in the utilisation of nitrogen sources other than ammonium and glutamine. In Aspergillus niger we have isolated three UV-induced areA mutants and constructed a well-defined disruption allele of the areA gene. The areA gene was genetically localised on Linkage Group III, 3.6 map units (m.u.) from bioA1 and 4.5 m.u. from lysA7. Analysis of the expression of the nitrate reductase encoding gene and of nitrate reductase activities show that the mutated areA strains behave as loss-of-function mutants and can be classified as areAr type. In addition, growth tests were performed using several nitrogen sources in combination with glucose. The results suggest that, unlike the case in A. nidulans, in A. niger the AreA protein also plays a role in the presence of ammonium. Furthermore, the spectrum of protease activities secreted by A. niger differs from that produced by A. nidulans, as only A. niger is able to degrade elastin.
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PMID:Isolation of UV-induced mutations in the areA nitrogen regulatory gene of Aspergillus niger, and construction of a disruption mutant. 1158 76

Nitrate assimilation genes encoding a nitrate transporter (YNT1), nitrite reductase (YNI1), a Zn(II)(2)Cys(6) transcriptional factor involved in nitrate induction (YNA1) and the nitrate reductase (YNR1) are clustered in the yeast Hansenula polymorpha. A second gene, termed YNA2 (yeast nitrate assimilation), was located seven nucleotides away from the 3' region of YNR1 gene. The cluster is flanked by an ORF encoding a protein with similarity to glutathione-S-transferase on the YNT1 side and an ORF with similarity to Saccharomyces cerevisiae Rad3p on the YNA2 side. The disruption of YNA2 confers the resulting null mutant strain with inability to grow in nitrate. The YNA2 gene encodes a putative protein of 618 residues bearing in the N-terminus the consensus sequence Cys-X(2)-Cys-X(6)-Cys-X(5-16)-Cys-X(2)-Cys-X(6-8)-Cys characteristic of the Zn(II)(2)Cys(6) transcriptional factors. YNA2 is therefore a member of the H. polymorpha nitrate assimilation gene cluster which is transcribed in the opposite direction to the rest of the members. Yna2p shares about 27% similarity with the H. polymorpha Yna1p Zn(II)(2)Cys(6) transcriptional factor involved in nitrate induction. Unlike the wild-type, the yna2::URA3 strain showed no expression of the nitrate assimilation genes when incubated in nitrate for 2 h. With regard to YNA2 expression, similar YNA2 transcript levels were observed in ammonium and in ammonium plus nitrate, but about a four-fold higher expression was observed in nitrate. However, this induction by nitrate of the YNA2 gene was not observed in the Deltayna1::URA3 strain. On the contrary, the pattern of YNA1 expression was the same in the wild-type as in the yna2::URA3 strain, indicating that YNA2 does not affect YNA1 expression.
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PMID:A second Zn(II)(2)Cys(6) transcriptional factor encoded by the YNA2 gene is indispensable for the transcriptional activation of the genes involved in nitrate assimilation in the yeast Hansenula polymorpha. 1192 Nov 2