NASST, 2 GENES INVOLVED IN THE INDUCTION OF THE ASSIMILATORY NITRITE-NITRATE REDUCTASE OPERON (NASAB) OF AZOTOBACTER-VINELANDII

Citation
Jc. Gutierrez et al., NASST, 2 GENES INVOLVED IN THE INDUCTION OF THE ASSIMILATORY NITRITE-NITRATE REDUCTASE OPERON (NASAB) OF AZOTOBACTER-VINELANDII, Molecular microbiology, 18(3), 1995, pp. 579-591
Citations number
50
Categorie Soggetti
Biology,Microbiology
Journal title
ISSN journal
0950382X
Volume
18
Issue
3
Year of publication
1995
Pages
579 - 591
Database
ISI
SICI code
0950-382X(1995)18:3<579:N2GIIT>2.0.ZU;2-5
Abstract
An operon including two new genes (nasS and nasT) has been defined, cl oned and sequenced. The deduced NASS protein is homologous to NRTA fro m Synechococcus sp. and to NASF from Klebsiella pneumoniae, two protei ns involved in nitrate uptake. The predicted NAST polypeptide is homol ogous to the regulator proteins of the two-component regulatory system s. NASS plays a negative regulatory role in the synthesis of the nitra te and nitrite reductase. NAST is required for the expression of the n itrite-nitrate reductase operon (nasAB). Expression of the nasST opero n is not under the control of the NTR system and is not regulated by t he nitrogen source. A Phi(nasA-lacZ) fusion has been used to analyse e xpression of the nasAB operon in three different genetic backgrounds w ith altered nitrate reductase activity. Beta-galactosidase activity in two of them was independent of nitrate but in a mutant unable to redu ce nitrate, nas-4 it was normally induced by nitrate.