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 Müller, P.
Right arrow Articles by Kahmann, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Müller, P.
Right arrow Articles by Kahmann, R.

 Previous Article  |  Next Article 

Eukaryotic Cell, June 2003, p. 609-617, Vol. 2, No. 3
1535-9778/03/$08.00+0     DOI: 10.1128/EC.2.3.609-617.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Guanyl Nucleotide Exchange Factor Sql2 and Ras2 Regulate Filamentous Growth in Ustilago maydis

Philip Müller, Jörg D. Katzenberger,{dagger} Gabriel Loubradou ,{ddagger} and Regine Kahmann*

Max Planck Institute for Terrestrial Microbiology, D-35043 Marburg, and Institute for Genetics and Microbiology, University of Munich, D-80638 Munich, Germany

Received 23 September 2002/ Accepted 22 February 2003

The cyclic AMP (cAMP)-signaling pathway regulates cell morphology and plays a crucial role during pathogenic development of the plant-pathogenic fungus Ustilago maydis. Strains lacking components of this signaling pathway, such as the G{alpha}-subunit Gpa3 or the adenylyl cyclase Uac1, are nonpathogenic and grow filamentously. On the other hand, strains exhibiting an activated cAMP pathway due to a dominant-active allele of gpa3 display a glossy colony phenotype and are unable to proliferate in plant tumors. Here we present the identification of sql2 as a suppressor of the glossy colony phenotype of a gpa3Q206L strain. sql2 encodes a protein with similarity to CDC25-like guanine nucleotide exchange factors, which are known to act on Ras proteins. Overexpression of sql2 leads to filamentous growth that cannot be suppressed by exogenous cAMP, suggesting that Sql2 does not act upstream of Uac1. To gain more insight in signaling processes regulated by Sql2, we isolated two genes encoding Ras proteins. Expression of dominant active alleles of ras1 and ras2 showed that Ras2 induces filamentous growth while Ras1 does not affect cell morphology but elevates pheromone gene expression. These results indicate that Ras1 and Ras2 fulfill different functions in U. maydis. Moreover, observed similarities between the filaments induced by sql2 and ras2 suggest that Sql2 is an activator of Ras2. Interestingly, sql2 deletion mutants are affected in pathogenic development but not in mating, indicating a specific function of sql2 during pathogenesis.

* Corresponding author. Mailing address: Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., D-35043 Marburg, Germany. Phone: 496421178501. Fax: 496421178509. E-mail: Kahmann{at}mailer.uni-marburg.de.

{dagger} Present address: Institute for Toxicology and Genetics, Karlsruhe Research Center, D-76021 Karlsruhe, Germany.

{ddagger} Present address: European Patent Office, D-80331 Munich, Germany.

Eukaryotic Cell, June 2003, p. 609-617, Vol. 2, No. 3
1535-9778/03/$08.00+0     DOI: 10.1128/EC.2.3.609-617.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Harispe, L., Portela, C., Scazzocchio, C., Penalva, M. A., Gorfinkiel, L. (2008). Ras GTPase-Activating Protein Regulation of Actin Cytoskeleton and Hyphal Polarity in Aspergillus nidulans. Eukaryot Cell 7: 141-153 [Abstract] [Full Text]  
  • Zhao, X., Mehrabi, R., Xu, J.-R. (2007). Mitogen-Activated Protein Kinase Pathways and Fungal Pathogenesis. Eukaryot Cell 6: 1701-1714 [Full Text]  
  • Park, G., Xue, C., Zhao, X., Kim, Y., Orbach, M., Xu, J.-R. (2006). Multiple Upstream Signals Converge on the Adaptor Protein Mst50 in Magnaporthe grisea. Plant Cell 18: 2822-2835 [Abstract] [Full Text]  
  • Schubert, D., Raudaskoski, M., Knabe, N., Kothe, E. (2006). Ras GTPase-Activating Protein Gap1 of the Homobasidiomycete Schizophyllum commune Regulates Hyphal Growth Orientation and Sexual Development.. Eukaryot Cell 5: 683-695 [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»