The yeast endosomal Na+/H+ exchanger, Nhx1, confers osmotolerance following acute hypertonic shock.
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.
Nass
Richard
R
Department of Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore MD 21205, USA1.
Rao
Rajini
R
Department of Physiology, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore MD 21205, USA1.
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
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