Filamentous growth of Saccharomyces cerevisiae is regulated by manganese

The Candida albicans INT1 gene is a virulence factor that contributes to bo th adhesion and filamentous growth of the fungus. Expression of INT1 in the budding yeast Saccharomyces cerevisiae directs both adhesion and filamento us growth. Because Int1p contains two predicted divalent cation-binding mot ifs, we asked whether divalent cations are important for the role of Int1p in filament formation. in this study, we found that INT1-induced filamentou s growth (I-IFG) is sensitive to the divalent cation chelator EDTA and that this EDTA sensitivity can be ameliorated by the addition of Mn2+, but not Mg2+ or Ca2+ ions. The addition of MnCl2 restored both the proportion of ce lls forming filaments and the length of filaments formed. Expression of INT 1 in S. cerevisiae mutants that reduce the intracellular concentration of M n2+ did not affect I-IFG. Interestingly, the Mn2+ dependence of I-IFG is no t dependent upon the presence of the putative divalent cation-binding domai ns found in INT1, Rather, we found that polarized growth induced by mutatio ns in CDC12 and CLA4 or by expression of excess SWE1 was also sensitive to EDTA treatment and was restored by the addition of MnCl2 but not by the add ition of CaCl2, Thus, our results suggest that in S. cerevisiae polarized g rowth is dependent upon the presence of Mn2+ ions. (C) 2000 Academic Press.