title: Nature of sterols affects plasma membrane behavior and yeast survival during dehydration.
abstract: The plasma membrane (PM) is a main site of injury during osmotic perturbation. Sterols, major lipids of the PM structure in eukaryotes, are thought to play a role in ensuring the stability of the lipid bilayer during physicochemical perturbations. Here, we investigated the relationship between the nature of PM sterols and resistance of the yeast Saccharomyces cerevisiae to hyperosmotic treatment. We compared the responses to osmotic dehydration (viability, sterol quantification, ultrastructure, cell volume, and membrane permeability) in the wild-type (WT) strain and the ergosterol mutant erg6Δ strain. Our main results suggest that the nature of membrane sterols governs the mechanical behavior of the PM during hyperosmotic perturbation. The mutant strain, which accumulates ergosterol precursors, was more sensitive to osmotic fluctuations than the WT, which accumulates ergosterol. The hypersensitivity of erg6Δ was linked to modifications of the membrane properties, such as stretching resistance and deformation, which led to PM permeabilization during the volume variation during the dehydration-rehydration cycles. Anaerobic growth of erg6Δ strain with ergosterol supplementation restored resistance to osmotic treatment. These results suggest a relationship between hydric stress resistance and the nature of PM sterols. We discuss this relationship in the context of the evolution of the ergosterol biosynthetic pathway.
authors.affiliation: Laboratoire de Génie des Procédés Microbiologiques et Alimentaires, Université de Bourgogne/AgroSup Dijon, 1, esplanade Erasme, 21000 Dijon, France.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Dupont
authors.forename: Laurent
authors.initials: L
authors.lastname: Beney
authors.forename: Thierry
authors.initials: T
authors.lastname: Ferreira
authors.forename: Patrick
authors.initials: P
authors.lastname: Gervais
mesh_terms: D002462:Cell Membrane / Q000737:chemistry* / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000502:physiology; D002849:Chromatography, Gas; D003681:Dehydration; D004875:Ergosterol / Q000032:analysis / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D009154:Mutation; D009997:Osmotic Pressure / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013261:Sterols / Q000032:analysis / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; D008780:Methyltransferases; C022670:delta 24-sterol methyltransferase; D004875:Ergosterol