CSIR-Institute of Microbial Technology, Sector 39-A, Chandigarh-160 036, India.
Sci Rep. 2017 Jan 12;7:40281. doi: 10.1038/srep40281.
Sphingolipids are involved in several cellular functions, including maintenance of cell wall integrity. To gain insight into the role of individual genes of sphingolipid biosynthetic pathway, we have screened Saccharomyces cerevisiae strains deleted in these genes for sensitivity to cell wall perturbing agents calcofluor white and congo red. Only deletants of FEN1 and SUR4 genes were found to be sensitive to both these agents. Candida albicans strains deleted in their orthologs, CaFEN1 and CaFEN12, respectively, also showed comparable phenotypes, and a strain deleted for both these genes was extremely sensitive to cell wall perturbing agents. Deletion of these genes was reported earlier to sensitise cells to amphotericin B (AmB), which is a polyene drug that kills the cells mainly by binding and sequestering ergosterol from the plasma membrane. Here we show that their AmB sensitivity is likely due to their cell wall defect. Further, we show that double deletant of C. albicans is defective in hyphae formation as well as biofilm development. Together this study reveals that deletion of FEN1 and SUR4 orthologs of C. albicans leads to impaired cell wall integrity and biofilm formation, which in turn sensitise cells to AmB.
鞘脂参与多种细胞功能，包括维持细胞壁完整性。为了深入了解鞘脂生物合成途径中各个基因的作用，我们筛选了这些基因缺失的酿酒酵母菌株，以检测它们对细胞壁扰动剂钙荧光白和刚果红的敏感性。只有 FEN1 和 SUR4 基因的缺失突变体对这两种试剂都敏感。其同源物 CaFEN1 和 CaFEN12 缺失的白色念珠菌菌株也表现出类似的表型，而这两个基因缺失的菌株对细胞壁扰动剂极其敏感。这些基因的缺失先前被报道会使细胞对两性霉素 B (AmB)敏感，两性霉素 B 是一种多烯类药物，主要通过与细胞膜上的麦角固醇结合并将其隔离来杀死细胞。在这里，我们表明它们对 AmB 的敏感性可能是由于它们的细胞壁缺陷。此外，我们还表明，白色念珠菌的双缺失突变体在菌丝形成和生物膜发育方面都有缺陷。综上所述，本研究揭示了白色念珠菌 FEN1 和 SUR4 同源物的缺失导致细胞壁完整性受损和生物膜形成减少，进而使细胞对 AmB 敏感。
