Difference in substrate specificity divides the yeast alkali-metal-cation/H(+) antiporters into two subfamilies.
Yeast plasma membrane Na(+)/H(+) antiporters (TC 2.A.36) share a high degree of similarity at the protein level. Expression of four antiporters (Saccharomyces cerevisiae Nha1p, Candida albicans Cnh1p, Zygosaccharomyces rouxii ZrSod2-22p and Schizosaccharomyces pombe sod2p) in a SACCH: cerevisiae mutant strain lacking both Na(+)-ATPase and Na(+)/H(+) antiporter genes made it possible to study the transport properties and contribution to cell salt tolerance of all antiporters under the same conditions. The ZrSod2-22p of the osmotolerant yeast Z. rouxii has the highest transport capacity for lithium and sodium but, like the SCHIZ: pombe sod2p, it does not recognize K(+) and Rb(+) as substrates. The SACCH: cerevisiae Nha1p and C. albicans Cnh1p have a broad substrate specificity for at least four alkali metal cations (Na(+), Li(+), K(+), Rb(+)), but their contribution to overall cell tolerance to high external concentration of toxic Na(+) and Li(+) cations seems to be lower compared to the antiporters of SCHIZ: pombe and especially Z. rouxii.
Kinclová
Olga
O
Laboratory of Microbiology and Genetics, UPRES A-7010-CNRS, Université Louis Pasteur, 67083 Strasbourg, France2.|Department of Membrane Transport, Institute of Physiology CzAcadSci, 14220 Prague 4, Czech Republic1.
Potier
Serge
S
Laboratory of Microbiology and Genetics, UPRES A-7010-CNRS, Université Louis Pasteur, 67083 Strasbourg, France2.
Sychrová
Hana
H
Department of Membrane Transport, Institute of Physiology CzAcadSci, 14220 Prague 4, Czech Republic1.
D002176:Candida albicans / Q000145:classification / Q000235:genetics; D002414:Cations, Monovalent / Q000378:metabolism; D007700:Kinetics; D008094:Lithium / Q000378:metabolism; D008670:Metals / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000235:genetics; D012568:Schizosaccharomyces / Q000145:classification / Q000235:genetics; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D015003:Yeasts / Q000145:classification / Q000378:metabolism*; D020068:Zygosaccharomyces / Q000145:classification / Q000235:genetics
D002414:Cations, Monovalent; D008670:Metals; D017923:Sodium-Hydrogen Exchangers; D008094:Lithium; D012964:Sodium; D012413:Rubidium; D011188:Potassium