The plasma membrane of the fungal pathogen Candida albicans forms a protective barrier that also mediates many processes needed for virulence, including cell wall synthesis, invasive hyphal morphogenesis, and nutrient uptake. Because compartmentalization of the plasma membrane is believed to coordinate these diverse activities, we examined plasma membrane microdomains termed eisosomes or membrane compartment of Can1 (MCC), which correspond to ∼200-nm-long furrows in the plasma membrane. A pil1∆ lsp1∆ mutant failed to form eisosomes and displayed strong defects in plasma membrane organization and morphogenesis, including extensive cell wall invaginations. Mutation of eisosome proteins Slm2, Pkh2, and Pkh3 did not cause similar cell wall defects, although pkh2∆ cells formed chains of furrows and pkh3∆ cells formed wider furrows, identifying novel roles for the Pkh protein kinases in regulating furrows. In contrast, the sur7∆ mutant formed cell wall invaginations similar to those for the pil1∆ lsp1∆ mutant even though it could form eisosomes and furrows. A PH-domain probe revealed that the regulatory lipid phosphatidylinositol 4,5-bisphosphate was enriched at sites of cell wall invaginations in both the sur7∆ and pil1∆ lsp1∆ cells, indicating that this contributes to the defects. The sur7∆ and pil1∆ lsp1∆ mutants displayed differential susceptibility to various types of stress, indicating that they affect overlapping but distinct functions. In support of this, many mutant phenotypes of the pil1∆ lsp1∆ cells were rescued by overexpressing SUR7 These results demonstrate that C. albicans eisosomes promote the ability of Sur7 to regulate plasma membrane organization.

• MeSH
• Cell Membrane metabolism   MeSH
• Cell Wall metabolism   MeSH
• Candida albicans metabolism   MeSH
• Endocytosis physiology   MeSH
• Phosphoproteins metabolism   MeSH
• Fungal Proteins metabolism   MeSH
• Hyphae metabolism   MeSH
• Membrane Microdomains metabolism   MeSH
• Membrane Proteins metabolism   MeSH
• Protein Kinases metabolism   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phosphoproteins MeSH
• Fungal Proteins MeSH
• Membrane Proteins MeSH
• Protein Kinases MeSH

We investigated the impact of the deletions of genes from the final steps in the biosynthesis of ergosterol (ERG6, ERG2, ERG3, ERG5, ERG4) on the physiological function of the Saccharomyces cerevisiae plasma membrane by a combination of biological tests and the diS-C3(3) fluorescence assay. Most of the erg mutants were more sensitive than the wild type to salt stress or cationic drugs, their susceptibilities were proportional to the hyperpolarization of their plasma membranes. The different sterol composition of the plasma membrane played an important role in the short-term and long-term processes that accompanied the exposure of erg strains to a hyperosmotic stress (effect on cell size, pH homeostasis and survival of yeasts), as well as in the resistance of cells to antifungal drugs. The pleiotropic drug-sensitive phenotypes of erg strains were, to a large extent, a result of the reduced efficiency of the Pdr5 efflux pump, which was shown to be more sensitive to the sterol content of the plasma membrane than Snq2p. In summary, the erg4Δ and erg6Δ mutants exhibited the most compromised phenotypes. As Erg6p is not involved in the cholesterol biosynthetic pathway, it may become a target for a new generation of antifungal drugs.

• MeSH
• ATP-Binding Cassette Transporters genetics   metabolism   MeSH
• Antifungal Agents pharmacology   MeSH
• Biosynthetic Pathways genetics   MeSH
• Cell Membrane chemistry   physiology   MeSH
• Ergosterol biosynthesis   chemistry   MeSH
• Fluconazole pharmacology   MeSH
• Microscopy, Fluorescence MeSH
• Hydrogen-Ion Concentration MeSH
• Membrane Potentials physiology   MeSH
• Methyltransferases genetics   metabolism   MeSH
• Drug Resistance, Multiple, Fungal drug effects   genetics   physiology   MeSH
• Molecular Structure MeSH
• Mutation MeSH
• Saccharomyces cerevisiae Proteins genetics   metabolism   MeSH
• Saccharomyces cerevisiae chemistry   genetics   physiology   MeSH
• Salt Tolerance genetics   physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• ATP-Binding Cassette Transporters MeSH
• Antifungal Agents MeSH
• delta 24-sterol methyltransferase MeSH Browser
• Ergosterol MeSH
• Fluconazole MeSH
• Methyltransferases MeSH
• PDR5 protein, S cerevisiae MeSH Browser
• Saccharomyces cerevisiae Proteins MeSH
• SNQ2 protein, S cerevisiae MeSH Browser

Regulation of gene expression on the level of translation and mRNA turnover is widely conserved evolutionarily. We have found that the main mRNA decay enzyme, exoribonuclease Xrn1, accumulates at the plasma membrane-associated eisosomes after glucose exhaustion in a culture of the yeast S. cerevisiae. Eisosomal localization of Xrn1 is not achieved in cells lacking the main component of eisosomes, Pil1, or Sur7, the protein accumulating at the membrane compartment of Can1 (MCC) - the eisosome-organized plasma membrane microdomain. In contrast to the conditions of diauxic shift, when Xrn1 accumulates in processing bodies (P-bodies), or acute heat stress, in which these cytosolic accumulations of Xrn1 associate with eIF3a/Rpg1-containing stress granules, Xrn1 is not accompanied by other mRNA-decay machinery components when it accumulates at eisosomes in post-diauxic cells. It is important that Xrn1 is released from eisosomes after addition of fermentable substrate. We suggest that this spatial segregation of Xrn1 from the rest of the mRNA-decay machinery reflects a general regulatory mechanism, in which the key enzyme is kept separate from the rest of mRNA decay factors in resting cells but ready for immediate use when fermentable nutrients emerge and appropriate metabolism reprogramming is required. In particular, the localization of Xrn1 to the eisosome, together with previously published data, accents the relevance of this plasma membrane-associated compartment as a multipotent regulatory site.

• MeSH
• Cell Membrane genetics   metabolism   MeSH
• Exoribonucleases genetics   metabolism   MeSH
• Gene Expression MeSH
• Glucose metabolism   MeSH
• Heat-Shock Response MeSH
• Recombinant Fusion Proteins genetics   metabolism   MeSH
• Genes, Reporter MeSH
• Saccharomyces cerevisiae Proteins genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Exoribonucleases MeSH
• Glucose MeSH
• Recombinant Fusion Proteins MeSH
• Saccharomyces cerevisiae Proteins MeSH
• XRN1 protein, S cerevisiae MeSH Browser

In many eukaryotes, a significant part of the plasma membrane is closely associated with the dynamic meshwork of cortical endoplasmic reticulum (cortical ER). We mapped temporal variations in the local coverage of the yeast plasma membrane with cortical ER pattern and identified micron-sized plasma membrane domains clearly different in cortical ER persistence. We show that clathrin-mediated endocytosis is initiated outside the cortical ER-covered plasma membrane zones. These cortical ER-covered zones are highly dynamic but do not overlap with the immobile and also endocytosis-inactive membrane compartment of Can1 (MCC) and the subjacent eisosomes. The eisosomal component Pil1 is shown to regulate the distribution of cortical ER and thus the accessibility of the plasma membrane for endocytosis.

• MeSH
• Cell Membrane physiology   MeSH
• Endocytosis * MeSH
• Endoplasmic Reticulum physiology   MeSH
• Phosphoproteins physiology   MeSH
• Clathrin physiology   MeSH
• Saccharomyces cerevisiae Proteins physiology   MeSH
• Saccharomyces cerevisiae physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Phosphoproteins MeSH
• Clathrin MeSH
• PIL1 protein, S cerevisiae MeSH Browser
• Saccharomyces cerevisiae Proteins MeSH