Cdc42 and Rac1 have fundamentally different roles in Candida albicans development.
Martine Bassilana, Robert Arkowitz
Inst.Signaling,Dev.Bio.&Cancer, CNRS UMR6543,Fac. des Sciences, Parc Valrose, Nice, 06108, France
Rho-type G proteins are key players in the cytoskeleton organization of virtually all eukaryotic cells. The small GTPase Cdc42 plays a crucial role in Candida albicans hyphal morphogenesis and pathogenicity. We identified C. albicans Rac1, another Rho-type G protein which has 52% identity with HsRac1 and 57% with CaCdc42. We investigated the importance of CaRac1 in hyphal morphogenesis and pathogenicity and the overlap between this G protein and CaCdc42 with respect to function and localization. In contrast to CaCdc42, we found that CaRac1 is not necessary for C. albicans viability, hyphal morphogenesis in response to serum and pathogenicity, using a murine model for systemic candidiasis. In addition, Fluorescence Recovery After Photobleaching (FRAP) experiments on CaRac1 and CaCdc42 in budding and hyphal cells indicate that these two G-proteins have different dynamics, suggesting different type of membrane interactions. Overall, our results indicate that these two Rho-type GTPases have fundamentally different roles in C. albicans development.