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 Viswanathan, P.
Right arrow Articles by Kroos, L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Viswanathan, P.
Right arrow Articles by Kroos, L.

 Previous Article  |  Next Article 

Journal of Bacteriology, May 2006, p. 3246-3256, Vol. 188, No. 9
0021-9193/06/$08.00+0     doi:10.1128/JB.188.9.3246-3256.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Role of {sigma}D in Regulating Genes and Signals during Myxococcus xanthus Development

Poorna Viswanathan,1 Mitchell Singer,2 and Lee Kroos1*

Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824,1 Section of Microbiology and Center for Genetics and Development, The University of California-Davis, Davis, California 956162

Received 14 January 2006/ Accepted 14 February 2006

Starvation-induced development of Myxococcus xanthus is an excellent model for biofilm formation because it involves cell-cell signaling to coordinate formation of multicellular mounds, gene expression, and cellular differentiation into spores. The role of {sigma}D, an alternative {sigma} factor important for viability in stationary phase and for stress responses, was investigated during development by measuring signal production, gene expression, and sporulation of a sigD null mutant alone and upon codevelopment with wild-type cells or signaling mutants. The sigD mutant responded to starvation by inducing (p)ppGpp synthesis normally but was impaired for production of A-signal, an early cell density signal, and for production of the morphogenetic C-signal. Induction of early developmental genes was greatly reduced, and expression of those that depend on A-signal was not restored by codevelopment with wild-type cells, indicating that {sigma}D is needed for cellular responses to A-signal. Despite these early developmental defects, the sigD mutant responded to C-signal supplied by codeveloping wild-type cells by inducing a subset of late developmental genes. {sigma}D RNA polymerase is dispensable for transcription of this subset, but a distinct regulatory class, which includes genes essential for sporulation, requires {sigma}D RNA polymerase or a gene under its control, cell autonomously. The level of sigD transcript in a relA mutant during growth is much lower than in wild-type cells, suggesting that (p)ppGpp positively regulates sigD transcription in growing cells. The sigD transcript level drops in wild-type cells after 20 min of starvation and remains low after 40 min but rises in a relA mutant after 40 min, suggesting that (p)ppGpp negatively regulates sigD transcription early in development. We conclude that {sigma}D synthesized during growth occupies a position near the top of a regulatory hierarchy governing M. xanthus development, analogous to {sigma} factors that control biofilm formation of other bacteria.

* Corresponding author. Mailing address: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824. Phone: (517) 355-9726. Fax: (517) 353-9334. E-mail: kroos{at}msu.edu.

Journal of Bacteriology, May 2006, p. 3246-3256, Vol. 188, No. 9
0021-9193/06/$08.00+0     doi:10.1128/JB.188.9.3246-3256.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Sowell, S. M., Norbeck, A. D., Lipton, M. S., Nicora, C. D., Callister, S. J., Smith, R. D., Barofsky, D. F., Giovannoni, S. J. (2008). Proteomic Analysis of Stationary Phase in the Marine Bacterium "Candidatus Pelagibacter ubique". Appl. Environ. Microbiol. 74: 4091-4100 [Abstract] [Full Text]  
  • Viswanathan, P., Murphy, K., Julien, B., Garza, A. G., Kroos, L. (2007). Regulation of dev, an Operon That Includes Genes Essential for Myxococcus xanthus Development and CRISPR-Associated Genes and Repeats. J. Bacteriol. 189: 3738-3750 [Abstract] [Full Text]  
  • Viswanathan, P., Ueki, T., Inouye, S., Kroos, L. (2007). Combinatorial regulation of genes essential for Myxococcus xanthus development involves a response regulator and a LysR-type regulator. Proc. Natl. Acad. Sci. USA 104: 7969-7974 [Abstract] [Full Text]  
  • Gronewold, T. M. A., Kaiser, D. (2007). Mutations of the Act Promoter in Myxococcus xanthus. J. Bacteriol. 189: 1836-1844 [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»