title: Implications of FPS1 deletion and membrane ergosterol content for glycerol efflux from Saccharomyces cerevisiae.
abstract: The deletion of the gene encoding the glycerol facilitator Fps1p was associated with an altered plasma membrane lipid composition in Saccharomyces cerevisiae. The S. cerevisiae fps1delta strain respectively contained 18 and 26% less ergosterol than the wild-type strain, at the whole-cell level and at the plasma membrane level. Other mutants with deficiencies in glycerol metabolism were studied to investigate any possible link between membrane ergosterol content and intracellular glycerol accumulation. In these mutants a modification in intracellular glycerol concentration, or in intra- to extracellular glycerol ratio was accompanied by a reduction in plasma membrane ergosterol content. However, there was no direct correlation between ergosterol content and intracellular glycerol concentration. Lipid composition influences the membrane permeability for solutes during adaptation of yeast cells to osmotic stress. In this study, ergosterol supplementation was shown to partially suppress the hypo-osmotic sensitivity phenotype of the fps1delta strain, leading to more efficient glycerol efflux, and improved survival. The erg-1 disruption mutant, which is unable to synthesise ergosterol, survived and recovered from the hypo-osmotic shock more successfully when the concentration of exogenously supplied ergosterol was increased. The results obtained suggest that a higher ergosterol content facilitates the flux of glycerol across the plasma membrane of S. cerevisiae cells.
authors.affiliation: Department of Microbiology, University of Stellenbosch, Matieland, South Africa.
authors.forename: T H
authors.initials: TH
authors.lastname: Toh
authors.forename: G
authors.initials: G
authors.lastname: Kayingo
authors.forename: M J
authors.initials: MJ
authors.lastname: van der Merwe
authors.forename: S G
authors.initials: SG
authors.lastname: Kilian
authors.forename: J E
authors.initials: JE
authors.lastname: Hallsworth
authors.forename: S
authors.initials: S
authors.lastname: Hohmann
authors.forename: B A
authors.initials: BA
authors.lastname: Prior
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability; D003470:Culture Media; D004875:Ergosterol / Q000378:metabolism*; D017353:Gene Deletion; D005990:Glycerol / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics* / Q000502:physiology; D009997:Osmotic Pressure; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000502:physiology
chemical_list: D003470:Culture Media; C093263:FPS1 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D005990:Glycerol; D004875:Ergosterol