The virulence of Candida species depends on many environmental conditions, including extracellular pH and concentration of alkali metal cations. Tests of the tolerance/sensitivity of four pathogenic Candida species (C. albicans, C. dubliniensis, C. glabrata, and C. parapsilosis) to alkali metal cations under various growth conditions revealed significant differences among these species. Though all of them can be classified as rather osmotolerant yeast species, they exhibit different levels of tolerance to different salts. C. parapsilosis and C. albicans are the most salt-tolerant in general; C. dubliniensis is the least tolerant on rich YPD media and C. glabrata on acidic (pH 3.5) minimal YNB medium. C. dubliniensis is relatively salt-sensitive in spite of its ability to maintain as high intracellular K(+)/Na(+) ratio as its highly salt-tolerant relative C. albicans. On the other hand, C. parapsilosis can grow in the presence of very high external NaCl concentrations in spite of its high intracellular Na(+) concentrations (and thus lower K(+)/Na(+) ratio) and thus resembles salt-tolerant (halophilic) Debaryomyces hansenii.

• MeSH
• Candida albicans patogenita   fyziologie   MeSH
• Candida glabrata patogenita   fyziologie   MeSH
• Candida metabolismus   patogenita   fyziologie   MeSH
• chlorid draselný analýza   farmakologie   MeSH
• chlorid lithný analýza   farmakologie   MeSH
• chlorid sodný analýza   farmakologie   MeSH
• druhová specificita MeSH
• soli MeSH
• tolerance k soli fyziologie   MeSH
• virulence MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• chlorid draselný MeSH
• chlorid lithný MeSH
• chlorid sodný MeSH
• soli MeSH

BACKGROUND: The virulence of Candida species depends on many environmental conditions. Extracellular pH and concentration of alkali metal cations belong among important factors. Nevertheless, the contribution of transporters mediating the exchange of alkali metal cations for protons across the plasma membrane to the cell salt tolerance and other physiological properties of various Candida species has not been studied so far. RESULTS: The tolerance/sensitivity of four pathogenic Candida species to alkali metal cations was tested and the role of one of the cation transporters in that tolerance (presumed to be the plasma-membrane Na+/H+ antiporter) was studied. The genes encoding these antiporters in the most and least salt sensitive species, C. dubliniensis and C. parapsilosis respectively, were identified, cloned and functionally expressed in the plasma membranes of Saccharomyces cerevisiae cells lacking their own cation exporters. Both CpCnh1 and CdCnh1 antiporters had broad substrate specificity and transported Na+, K+, Li+, and Rb+. Their activity in S. cerevisiae cells differed; CpCnh1p provided cells with a much higher salt tolerance than the CdCnh1 antiporter. The observed difference in activity was confirmed by direct measurements of sodium and potassium efflux mediated by these antiporters. CONCLUSION: We have cloned two genes encoding putative Na+/H+ antiporters in C. parapsilosis and C. dubliniensis, and characterized the transport properties of encoded proteins. Our results show that the activity of plasma-membrane Na+/H+ antiporters is one of the factors determining the tolerance of pathogenic Candida species to high external concentrations of alkali metal cations.

• MeSH
• alkalické kovy metabolismus   MeSH
• Candida genetika   růst a vývoj   metabolismus   patogenita   MeSH
• draslík metabolismus   MeSH
• fluorescenční mikroskopie MeSH
• fungální proteiny genetika   metabolismus   MeSH
• kationty metabolismus   MeSH
• lithium metabolismus   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• Na(+)-H(+) antiport genetika   metabolismus   MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   růst a vývoj   metabolismus   MeSH
• sekundární struktura proteinů MeSH
• sekvence nukleotidů MeSH
• soli metabolismus   MeSH
• substrátová specifita MeSH
• superoxiddismutasa 1 MeSH
• superoxiddismutasa metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• alkalické kovy MeSH
• CNH1 protein, Candida albicans MeSH Prohlížeč
• draslík MeSH
• fungální proteiny MeSH
• kationty MeSH
• lithium MeSH
• membránové proteiny MeSH
• Na(+)-H(+) antiport MeSH
• NHA1 protein, S cerevisiae MeSH Prohlížeč
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH
• soli MeSH
• superoxiddismutasa 1 MeSH
• superoxiddismutasa MeSH

The Saccharomyces cerevisiae genome contains three genes encoding alkali metal cation/H+ antiporters (Nha1p, Nhx1p, Kha1p) that differ in cell localization, substrate specificity and physiological function. Systematic genome sequencing of other yeast species revealed highly conserved homologous ORFs in all of them. We compared the yeast sequences both at DNA and protein levels. The subfamily of yeast endosomal/prevacuolar Nhx1 antiporters is closely related to mammalian plasma membrane NHE proteins and to both plasma membrane and vacuolar plant antiporters. The high sequence conservation within this subfamily of yeast antiporters suggests that Nhx1p is of great importance in cell physiology. Yeast Kha1 proteins probably belong to the same subfamily as bacterial antiporters, whereas Nhal proteins form a distinct subfamily.

• MeSH
• DNA fungální analýza   MeSH
• draslíko-vodíkové antiportéry chemie   klasifikace   genetika   MeSH
• fylogeneze MeSH
• membránové proteiny chemie   klasifikace   genetika   MeSH
• molekulární sekvence - údaje MeSH
• Na(+)-H(+) antiport chemie   klasifikace   genetika   MeSH
• proteiny přenášející kationty chemie   klasifikace   genetika   MeSH
• Saccharomyces cerevisiae - proteiny chemie   klasifikace   genetika   MeSH
• sekvence aminokyselin MeSH
• sekvenční analýza DNA MeSH
• sekvenční homologie aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA fungální MeSH
• draslíko-vodíkové antiportéry MeSH
• KHA1 protein, S cerevisiae MeSH Prohlížeč
• membránové proteiny MeSH
• Na(+)-H(+) antiport MeSH
• NHA1 protein, S cerevisiae MeSH Prohlížeč
• NHX1 protein, S cerevisiae MeSH Prohlížeč
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH

Saccharomyces cerevisiae uses different mechanisms to adapt to changes in environmental osmolarity. Upon hyperosmotic shock, cells first mobilize a rapid rescue system that prevents excessive loss of ions and water; then in the adaptation period they accumulate a compatible solute (glycerol). When subjected to hypoosmotic shock, they rapidly release intracellular stocks of glycerol to reduce intracellular osmolarity and prevent bursting. The plasma membrane Nha1 alkali metal cation/H+ antiporter is not important in helping the cells to survive a sudden drop in external osmolarity, but is involved in the cell response to hyperosmotic shock. For this role, its long hydrophilic C-terminus is indispensable. The capacity of the Nha1 antiporter to transport potassium is regulated by Hog1 kinase. Upon sorbitol-mediated stress, the Nha1p potassium export activity decreases in order to maintain a higher intracellular concentration of solutes. The C-terminal-less Nha1 version is not inactivated and its potassium efflux activity renders cells very sensitive to hyperosmotic shock. Taken together, our results suggest an important role of Nha1p and its C-terminus in the immediate response to hyperosmotic shock as part of the rapid rescue mechanism.

• MeSH
• fyziologická adaptace fyziologie   MeSH
• iontový transport fyziologie   MeSH
• membránové proteiny genetika   metabolismus   MeSH
• mitogenem aktivované proteinkinasy genetika   metabolismus   MeSH
• Na(+)-H(+) antiport genetika   metabolismus   MeSH
• osmotický tlak MeSH
• proteiny přenášející kationty genetika   metabolismus   MeSH
• regulace genové exprese u hub fyziologie   MeSH
• Saccharomyces cerevisiae - proteiny genetika   metabolismus   MeSH
• Saccharomyces cerevisiae genetika   metabolismus   MeSH
• terciární struktura proteinů genetika   MeSH
• upregulace fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• HOG1 protein, S cerevisiae MeSH Prohlížeč
• membránové proteiny MeSH
• mitogenem aktivované proteinkinasy MeSH
• Na(+)-H(+) antiport MeSH
• NHA1 protein, S cerevisiae MeSH Prohlížeč
• proteiny přenášející kationty MeSH
• Saccharomyces cerevisiae - proteiny MeSH