title: The yeast endosomal Na+/H+ exchanger, Nhx1, confers osmotolerance following acute hypertonic shock.
abstract: Osmotolerance in yeast is regulated by at least two distinct mechanisms. The acquired response occurs following long-term exposure to hypertonic medium and requires the induction of the HOG-MAP (high-osmolarity glycerol mitogen-activated protein) kinase cascade to increase levels of the osmolyte glycerol. The acute response occurs following sudden exposure to high osmotica and appears to be dependent on normal vacuole function. In this study it is reported that the yeast endosomal/prevacuolar Na+/H+ exchanger Nhx1 contributes to osmotolerance following sudden exposure to hyperosmotic media. Vacuolar shrinkage and recovery in response to osmotic shock was altered in the (delta)nhx1 null mutant. Our results also show that the osmotolerance conferred by Nhx1 contributes to the postdiauxic/stationary-phase resistance to osmotic stress and allows for the continued growth of cells until the acquired osmotolerance response can occur.
authors.affiliation: Department of Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore MD 21205, USA1.
authors.forename: Richard
authors.initials: R
authors.lastname: Nass
authors.affiliation: Department of Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore MD 21205, USA1.
authors.forename: Rajini
authors.initials: R
authors.lastname: Rao
mesh_terms: D027682:Cation Transport Proteins; D003470:Culture Media / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D006982:Hypertonic Solutions; D018613:Microscopy, Confocal; D009997:Osmotic Pressure; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000502:physiology*; D013012:Sorbitol; D013997:Time Factors; D014617:Vacuoles; D014882:Water-Electrolyte Balance
chemical_list: D027682:Cation Transport Proteins; D003470:Culture Media; D005656:Fungal Proteins; D006982:Hypertonic Solutions; C492183:NHX1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017923:Sodium-Hydrogen Exchangers; D013012:Sorbitol