Bradyrhizobium japonicum NnrR, a Denitrification Regulator, Expands the FixLJ-FixK sub(2) Regulatory Cascade

In Bradyrhizobium japonicum, a gene named nnrR was identified which encodes a protein with high similarity to FNR/CRP-type transcriptional regulators. Mutant strains carrying an nnrR null mutation were unable to grow anaerobically in the presence of nitrate or nitrite, and they lacked both nitrate a...

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Bibliographic Details
Published in:Journal of bacteriology 2003-07, Vol.185 (13), p.3978-3982
Main Authors: Mesa, S, Bedmar, E J, Chanfon, A, Hennecke, H, Fischer, H
Format: Article
Language:English
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Summary:In Bradyrhizobium japonicum, a gene named nnrR was identified which encodes a protein with high similarity to FNR/CRP-type transcriptional regulators. Mutant strains carrying an nnrR null mutation were unable to grow anaerobically in the presence of nitrate or nitrite, and they lacked both nitrate and nitrite reductase activities. Anaerobic activation of an nnrR'-'lacZ fusion required FixLJ and FixK sub(2). In turn, N oxide- mediated induction of nir and nor genes encoding nitrite and nitric oxide reductase, respectively, depended on NnrR. Thus, NnrR expands the FixLJ- FixK sub(2) regulatory cascade by an additional control level which integrates the N oxide signal required for maximal induction of the denitrification genes.
ISSN:0021-9193
DOI:10.1128/JB.185.13.3978-3982.2003