Identification of a cAMP-dependent protein kinase catalytic subunit required for virulence and morphogenesis in Ustilago maydis
- Biotechnology Laboratory, Departments of Microbiology and Immunology, and Plant Science, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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Communicated by Eugene W. Nester, University of Washington, Seattle, WA (received for review December 13, 1997)
Abstract
Ustilago maydis, a fungal pathogen of maize, alternates between budding and filamentous growth in response to mating and other environmental signals. Defects in components of the cAMP signaling pathway affect this morphological transition and reveal an association of budding growth with elevated cAMP levels and filamentous growth with low cAMP levels. We have identified two genes, adr1 and uka1, encoding catalytic subunits of cAMP-dependent protein kinase (PKA). Disruption of adr1 resulted in a constitutively filamentous growth phenotype similar to that of mutants deficient in adenylyl cyclase. Importantly, adr1 is required for pathogenicity and is responsible for the majority of PKA activity in fungal cells. In contrast, uka1 has little influence on pathogenicity, and deletion of the uka1 gene does not affect cell morphology. These results provide compelling evidence that regulated PKA activity is crucial during infectious development of U. maydis.
Footnotes
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↵ * To whom reprint requests should be addressed at: Biotechnology Laboratory, 237-6174 University Blvd., University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada. e-mail: kronstad{at}unixg.ubc.ca.
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Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. AF025290).
- ABBREVIATION:
- PKA,
- cAMP-dependent protein kinase
- Copyright © 1998, The National Academy of Sciences
