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
• Metals, Alkali metabolism   MeSH
• Candida genetics   growth & development   metabolism   pathogenicity   MeSH
• Potassium metabolism   MeSH
• Microscopy, Fluorescence MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Cations metabolism   MeSH
• Lithium metabolism   MeSH
• Membrane Proteins genetics   metabolism   MeSH
• Molecular Sequence Data MeSH
• Sodium-Hydrogen Exchangers genetics   metabolism   MeSH
• Cation Transport Proteins genetics   metabolism   MeSH
• Saccharomyces cerevisiae Proteins genetics   metabolism   MeSH
• Saccharomyces cerevisiae genetics   growth & development   metabolism   MeSH
• Protein Structure, Secondary MeSH
• Base Sequence MeSH
• Salts metabolism   MeSH
• Substrate Specificity MeSH
• Superoxide Dismutase-1 MeSH
• Superoxide Dismutase metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Metals, Alkali MeSH
• CNH1 protein, Candida albicans MeSH Browser
• Potassium MeSH
• Fungal Proteins MeSH
• Cations MeSH
• Lithium MeSH
• Membrane Proteins MeSH
• Sodium-Hydrogen Exchangers MeSH
• NHA1 protein, S cerevisiae MeSH Browser
• Cation Transport Proteins MeSH
• Saccharomyces cerevisiae Proteins MeSH
• Salts MeSH
• Superoxide Dismutase-1 MeSH
• Superoxide Dismutase MeSH

Yarrowia lipolytica plasma-membrane Na+/H+ antiporter, encoded by the YlNHA2 gene, is a very efficient exporter of surplus sodium from the cytosol. Its heterologous expression in Saccharomyces cerevisiae wild-type laboratory strains increased their sodium tolerance more efficiently than the expression of ZrSod2-22 antiporter from the osmotolerant yeast Zygosaccharomvces rouxii.

• MeSH
• Antifungal Agents pharmacology   MeSH
• Gene Expression MeSH
• Fungal Proteins genetics   metabolism   MeSH
• Cloning, Molecular MeSH
• Sodium-Hydrogen Exchangers genetics   metabolism   MeSH
• Recombinant Proteins genetics   metabolism   MeSH
• Saccharomyces cerevisiae drug effects   genetics   growth & development   metabolism   MeSH
• Salts pharmacology   MeSH
• Yarrowia enzymology   genetics   MeSH
• Zygosaccharomyces enzymology   genetics   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antifungal Agents MeSH
• Fungal Proteins MeSH
• Sodium-Hydrogen Exchangers MeSH
• Recombinant Proteins MeSH
• Salts MeSH