This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bauer, E.
Right arrow Articles by Hennecke, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bauer, E.
Right arrow Articles by Hennecke, H.

 Previous Article  |  Next Article 

Journal of Bacteriology, August 1998, p. 3853-3863, Vol. 180, No. 15
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

Expression of the fixR-nifA Operon in Bradyrhizobium japonicum Depends on a New Response Regulator, RegR

Evelyne Bauer, Thomas Kaspar, Hans-Martin Fischer, and Hauke Hennecke*

Mikrobiologisches Institut, Eidgenössische Technische Hochschule, CH-8092 Zürich, Switzerland

Received 2 February 1998/Accepted 27 May 1998

Many nitrogen fixation-associated genes in the soybean symbiont Bradyrhizobium japonicum are regulated by the transcriptional activator NifA, whose activity is inhibited by aerobiosis. NifA is encoded in the fixR-nifA operon, which is expressed at a low level under aerobic conditions and induced approximately fivefold under low-oxygen tension. This induction depends on a -24/-12-type promoter (fixRp1) that is recognized by the sigma 54 RNA polymerase and activated by NifA. Low-level aerobic expression and part of the anaerobic expression originates from a second promoter (fixRp2) that overlaps with fixRp1 and depends on an upstream DNA region (UAS) located around position -68 (H. Barrios, H. M. Fischer, H. Hennecke, and E. Morett, J. Bacteriol. 177:1760-1765, 1995). A protein binding to the UAS was previously postulated to act as an activator. This protein has now been purified, and the corresponding gene (regR) has been cloned. On the basis of the predicted amino acid sequence, RegR belongs to the family of response regulators of two-component regulatory systems. We identified upstream of the regR gene an additional gene (regS) encoding a putative sensor kinase. A regR mutant was constructed in which neither a specific UAS-binding activity nor fixRp2-dependent transcript formation and fixR'-'lacZ expression was detected in aerobically grown cells. Anaerobic fixR'-'lacZ expression was also decreased in regR mutants to about 10% of the level observed in the wild type. Similarly, regR mutants showed only about 2% residual nitrogen fixation activity, but unlike nodules induced by nifA mutants, the morphology of those nodules was normal, displaying no signs of necrosis. While regR mutants grew only slightly slower in free-living, aerobic conditions, they displayed a strong growth defect under anaerobic conditions. The phenotypic properties of regS mutants differed only marginally, if at all, from those of the wild type, suggesting the existence of a compensating sensor activity in these strains. The newly identified RegR protein may be regarded as a master regulator in the NifA-dependent network controlling nif and fix gene expression in B. japonicum.

* Corresponding author. Mailing address: Mikrobiologisches Institut, Eidgenössische Technische Hochschule, Schmelzbergstrasse 7, CH-8092 Zürich, Switzerland. Phone: 41-1-632-3318. Fax: 41-1-632-1382. E-mail: hennecke{at}micro.biol.ethz.ch.

Journal of Bacteriology, August 1998, p. 3853-3863, Vol. 180, No. 15
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:

  • Lindemann, A., Moser, A., Pessi, G., Hauser, F., Friberg, M., Hennecke, H., Fischer, H.-M. (2007). New Target Genes Controlled by the Bradyrhizobium japonicum Two-Component Regulatory System RegSR. J. Bacteriol. 189: 8928-8943 [Abstract] [Full Text]  
  • Jones, D. F., Stenzel, R. A., Donohue, T. J. (2005). Mutational analysis of the C-terminal domain of the Rhodobacter sphaeroides response regulator PrrA. Microbiology 151: 4103-4110 [Abstract] [Full Text]  
  • Martinez, M., Palacios, J. M., Imperial, J., Ruiz-Argueso, T. (2004). Symbiotic Autoregulation of nifA Expression in Rhizobium leguminosarum bv. viciae. J. Bacteriol. 186: 6586-6594 [Abstract] [Full Text]  
  • Elsen, S., Swem, L. R., Swem, D. L., Bauer, C. E. (2004). RegB/RegA, a Highly Conserved Redox-Responding Global Two-Component Regulatory System. Microbiol. Mol. Biol. Rev. 68: 263-279 [Abstract] [Full Text]  
  • Sciotti, M.-A., Chanfon, A., Hennecke, H., Fischer, H.-M. (2003). Disparate Oxygen Responsiveness of Two Regulatory Cascades That Control Expression of Symbiotic Genes in Bradyrhizobium japonicum. J. Bacteriol. 185: 5639-5642 [Abstract] [Full Text]  
  • Tichi, M. A., Tabita, F. R. (2002). Metabolic Signals That Lead to Control of CBB Gene Expression in Rhodobacter capsulatus. J. Bacteriol. 184: 1905-1915 [Abstract] [Full Text]  
  • Comolli, J. C., Carl, A. J., Hall, C., Donohue, T. (2002). Transcriptional Activation of the Rhodobacter sphaeroides Cytochrome c2 Gene P2 Promoter by the Response Regulator PrrA. J. Bacteriol. 184: 390-399 [Abstract] [Full Text]  
  • Tichi, M. A., Tabita, F. R. (2001). Interactive Control of Rhodobacter capsulatus Redox-Balancing Systems during Phototrophic Metabolism. J. Bacteriol. 183: 6344-6354 [Abstract] [Full Text]  
  • Fischer, H.-M., Velasco, L., Delgado, M. J., Bedmar, E. J., Schären, S., Zingg, D., Göttfert, M., Hennecke, H. (2001). One of Two hemN Genes in Bradyrhizobium japonicum Is Functional during Anaerobic Growth and in Symbiosis. J. Bacteriol. 183: 1300-1311 [Abstract] [Full Text]  
  • Korotkova, N., Lidstrom, M. E. (2001). Connection between Poly-{beta}-Hydroxybutyrate Biosynthesis and Growth on C1 and C2 Compounds in the Methylotroph Methylobacterium extorquens AM1. J. Bacteriol. 183: 1038-1046 [Abstract] [Full Text]  
  • Emmerich, R., Strehler, P., Hennecke, H., Fischer, H.-M. (2000). An imperfect inverted repeat is critical for DNA binding of the response regulator RegR of Bradyrhizobium japonicum. Nucleic Acids Res 28: 4166-4171 [Abstract] [Full Text]  
  • Souza, E. M., Pedrosa, F. O., Rigo, L. U., Machado, H. B., Yates, M. G. (2000). Expression of the nifA gene of Herbaspirillum seropedicae: role of the NtrC and NifA binding sites and of the -24/-12 promoter element. Microbiology 146: 1407-1418 [Abstract] [Full Text]  
  • Elsen, S., Dischert, W., Colbeau, A., Bauer, C. E. (2000). Expression of Uptake Hydrogenase and Molybdenum Nitrogenase in Rhodobacter capsulatus Is Coregulated by the RegB-RegA Two-Component Regulatory System. J. Bacteriol. 182: 2831-2837 [Abstract] [Full Text]  
  • Nienaber, A., Huber, A., Göttfert, M., Hennecke, H., Fischer, H.-M. (2000). Three New NifA-Regulated Genes in the Bradyrhizobium japonicum Symbiotic Gene Region Discovered by Competitive DNA-RNA Hybridization. J. Bacteriol. 182: 1472-1480 [Abstract] [Full Text]  
  • Masuda, S., Matsumoto, Y., Nagashima, K. V. P., Shimada, K., Inoue, K., Bauer, C. E., Matsuura, K. (1999). Structural and Functional Analyses of Photosynthetic Regulatory Genes regA and regB from Rhodovulum sulfidophilum, Roseobacter denitrificans, and Rhodobacter capsulatus. J. Bacteriol. 181: 4205-4215 [Abstract] [Full Text]  
  • Du, S., Kouadio, J.-L. K., Bauer, C. E. (1999). Regulated Expression of a Highly Conserved Regulatory Gene Cluster Is Necessary for Controlling Photosynthesis Gene Expression in Response to Anaerobiosis in Rhodobacter capsulatus. J. Bacteriol. 181: 4334-4341 [Abstract] [Full Text]  
  • Dubbs, J. M., Bird, T. H., Bauer, C. E., Tabita, F. R. (2000). Interaction of CbbR and RegA* Transcription Regulators with the Rhodobacter sphaeroides cbbIPromoter-Operator Region. J. Biol. Chem. 275: 19224-19230 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»