Calmodulin Binding to Dfi1p Promotes Invasiveness of Candida albicans
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Authors: | Talya R Davis Paola C Zucchi Carol A Kumamoto |
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Institution: | 1. Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts, United States of America.; 2. Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America.; New Jersey Medical School, Rutgers University, United States of America, |
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Abstract: | Candida albicans, a dimorphic fungus, undergoes hyphal development in response to many different environmental cues, including growth in contact with a semi-solid matrix. C. albicans forms hyphae that invade agar when cells are embedded in or grown on the surface of agar, and the integral membrane protein Dfi1p is required for this activity. In addition, Dfi1p is required for full activation of mitogen activated protein kinase Cek1p during growth on agar. In this study, we identified a putative calmodulin binding motif in the C-terminal tail of Dfi1p. This region of Dfi1p bound to calmodulin in vitro, and mutations that affected this region affected both calmodulin binding in vitro and invasive filamentation when incorporated into the full length Dfi1p protein. Moreover, increasing intracellular calcium levels led to calcium-dependent, Dfi1p-dependent Cek1p activation. We propose that conformational changes in Dfi1p in response to environmental conditions encountered during growth allow the protein to bind calmodulin and initiate a signaling cascade that activates Cek1p. |
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