Critical role for CaFEN1 and CaFEN12 of Candida albicans in cell wall integrity and biofilm formation

Abstract

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.

Candida albicans gains azole resistance by altering sphingolipid composition

“…4b ), indicating that the screen was successful. Among the highest ranking genes were FEN1 , FEN12 , and ARV1 which play important roles in sphingolipid biosynthesis 49 , 50 . The understanding that sphingolipids are major components of fungal cell membrane and interact both physically and functionally with ergosterol 30 , 51 , 52 , the target of azole and polyene antifungal drugs, prompted us to conduct a comprehensive analysis of FEN1 and FEN12 .…”

Blocking β‐1,6‐glucan synthesis by deleting KRE6 and SKN1 attenuates the virulence of Candida albicans

“…Biofilm formation is important for the pathogenicity of C. albicans and hyphal growth is an important component of the biofilm architecture (Desai and Mitchell, ; Alfatah et al ., ). Next, we investigated the ability of the kre6 Δ/Δ, skn1 Δ/Δ and kre6 Δ/Δ skn1 Δ/Δ mutant to form biofilms in 96‐well plates using the XTT reduction method (Alfatah et al ., ). Compared with SC5314, the ability of the kre6 Δ/Δ skn1 Δ/Δ mutant to form biofilm was reduced by ~90% (Fig.…”

“…Biofilm formation was performed largely as described previously by Alfatah et al . (). Briefly, C. albicans cells were grown to mid‐log phase in YPD medium, washed twice with sterile PBS and suspended in phenol red‐free DMEM medium at a density 10 6 cells/mL.…”

The Significance of Lipids to Biofilm Formation in Candida albicans: An Emerging Perspective

“…The ipt1 Δ/Δ cells display fewer lipid rafts on the hyphal membrane and reduced biofilm formation [52]. Another study demonstrates a role for fatty acid elongases coding genes, FEN1 ( ELO2 ) and SUR4 ( ELO3 ) that are involved in sphingolipid biosynthesis, in biofilm formation [103]. These genes along with ELO1 synthesize C14-C16 long chain fatty acids, up to C24 very long chain fatty acids (VLCFA) and C24 or C26 VLCFA.…”

“…Deletions in FEN1 and SUR4 results in the production of short chain fatty acids and leads to reduced sphingolipid levels. SEM analysis of poly-L-lysine coated cover slips inoculated with fen1 Δ/Δ and sur4 Δ/Δ mutants show defect in biofilm formation [103]. Furthermore, the loss of de novo phosphatidylethanolamine (PE) and phosphatidylserine (PS) synthesis and its impact on the phospholipidome of C. albicans has also been demonstrated [104].…”