Asleson C M, Asleson J C, Malandra E, Johnston S, Berman J
Department of Genetics, Cell Biology and Development, University of Minnesota, 250 Biological Sciences Center, St. Paul, Minnesota 55108, USA.
Fungal Genet Biol. 2000 Jul;30(2):155-62. doi: 10.1006/fgbi.2000.1214.
The Candida albicans INT1 gene is a virulence factor that contributes to both adhesion and filamentous growth of the fungus. Expression of INT1 in the budding yeast Saccharomyces cerevisiae directs both adhesion and filamentous growth. Because Int1p contains two predicted divalent cation-binding motifs, we asked whether divalent cations are important for the role of Int1p in filament formation. In this study, we found that INT1-induced filamentous growth (I-IFG) is sensitive to the divalent cation chelator EDTA and that this EDTA sensitivity can be ameliorated by the addition of Mn(2+), but not Mg(2+) or Ca(2+) ions. The addition of MnCl(2) restored both the proportion of cells forming filaments and the length of filaments formed. Expression of INT1 in S. cerevisiae mutants that reduce the intracellular concentration of Mn(2+) did not affect I-IFG. Interestingly, the Mn(2+) dependence of I-IFG is not dependent upon the presence of the putative divalent cation-binding domains found in INT1. Rather, we found that polarized growth induced by mutations in CDC12 and CLA4 or by expression of excess SWE1 was also sensitive to EDTA treatment and was restored by the addition of MnCl(2) but not by the addition of CaCl(2). Thus, our results suggest that in S. cerevisiae polarized growth is dependent upon the presence of Mn(2+) ions.
白色念珠菌INT1基因是一种毒力因子，对该真菌的黏附及丝状生长均有作用。INT1在出芽酵母酿酒酵母中的表达可指导黏附和丝状生长。由于Int1p含有两个预测的二价阳离子结合基序，我们探究了二价阳离子对于Int1p在丝状形成中的作用是否重要。在本研究中，我们发现INT1诱导的丝状生长（I-IFG）对二价阳离子螯合剂EDTA敏感，并且添加Mn(2+)可改善这种对EDTA的敏感性，而添加Mg(2+)或Ca(2+)离子则不能。添加MnCl(2)可恢复形成丝状的细胞比例及所形成丝状的长度。在降低细胞内Mn(2+)浓度的酿酒酵母突变体中表达INT1并不影响I-IFG。有趣的是，I-IFG对Mn(2+)的依赖性并不取决于INT1中假定的二价阳离子结合结构域的存在。相反，我们发现由CDC12和CLA4突变或过量表达SWE1诱导的极性生长对EDTA处理也敏感，并且添加MnCl(2)可恢复，而添加CaCl(2)则不能。因此，我们的结果表明在酿酒酵母中极性生长依赖于Mn(2+)离子的存在。
