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Eukaryotic Cell, May 2009, p. 756-767, Vol. 8, No. 5
1535-9778/09/$08.00+0     doi:10.1128/EC.00332-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Depletion of the Cullin Cdc53p Induces Morphogenetic Changes in Candida albicans{triangledown} ,{dagger}

Katharina Trunk,1 Patrick Gendron,1 André Nantel,2 Sébastien Lemieux,1 Terry Roemer,3 and Martine Raymond1,4*

Institute for Research in Immunology and Cancer, Université de Montréal, Montreal, Quebec H3C 3J7, Canada,1 Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada,2 Merck & Co., Inc., Department of Infectious Diseases, Rahway, New Jersey 07065,3 Department of Biochemistry, Université de Montréal, Montreal, Quebec H3C 3J7, Canada4

Received 1 October 2008/ Accepted 18 February 2009

Candida albicans is an important opportunistic human fungal pathogen that can cause both mucosal and systemic infections in immunocompromised patients. Critical for the virulence of C. albicans is its ability to undergo a morphological transition from yeast to hyphal growth mode. Proper induction of filamentation is dependent on the ubiquitination pathway, which targets proteins for proteasome-mediated protein degradation or activates them for signaling events. In the present study, we evaluated the role of ubiquitination in C. albicans by impairing the function of the major ubiquitin-ligase complex SCF. This was done by depleting its backbone, the cullin Cdc53p (orf19.1674), using a tetracycline downregulatable promoter system. Cdc53p-depleted cells displayed an invasive phenotype and constitutive filamentation under conditions favoring yeast growth mode, both on solid and in liquid media. In addition, these cells exhibited an early onset of cell death, as judged from propidium iodide staining, suggesting that CDC53 is an essential gene in C. albicans. To identify Cdc53p-dependent pathways in C. albicans, a genome-wide expression analysis was carried out that revealed a total of 425 differentially expressed genes (fold change, ≥2; P ≤ 0.05) with 192 up- and 233 downregulated genes in the CDC53-repressed mutant compared to the control strain. GO term analysis identified biological processes significantly affected by Cdc53p depletion, including amino acid starvation response, with 14 genes being targets of the transcriptional regulator Gcn4p, and reductive iron transport. These results indicate that Cdc53p enables C. albicans to adequately respond to environmental signals.

* Corresponding author. Mailing address: Institute for Research in Immunology and Cancer, Université de Montréal, P.O. Box 6128, Station Centre-Ville, Montreal, Quebec H3C 3J7, Canada. Phone: (514) 343-6746. Fax: (514) 343-6843. E-mail: martine.raymond{at}umontreal.ca

{triangledown} Published ahead of print on 6 March 2009.

{dagger} Supplemental material for this article may be found at http://ec.asm.org/.

Eukaryotic Cell, May 2009, p. 756-767, Vol. 8, No. 5
1535-9778/09/$08.00+0     doi:10.1128/EC.00332-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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