P-type ATPases mediate sodium and potassium effluxes in Schwanniomyces occidentalis.
Two genes isolated from Schwanniomyces occidentalis, ENA1 and ENA2, encode P-type ATPases highly homologous to the Na-ATPases of Saccharomyces cerevisiae and complement the Na+ sensitivity of an S. cerevisiae mutant strain lacking its own Na-ATPases. The expression of both ENA1 and ENA2 was highly dependent on a high external pH, but whereas a high pH was sufficient for the expression of ENA2, the expression of ENA1 required a high pH and the presence of Na+. Disruption of ENA1 rendered the cells less tolerant to Na+ than the wild-type strain and decreased their capacity for Na+ extrusion. Disruption of ENA2 did not affect Na+ tolerance, but decreased both the growth at high pH and K+ efflux. We discuss these results and propose that fungal Na-ATPases should be considered alkali cation ATPases. By sequence comparison, we found that fungal Na-ATPases form a homogeneous group that can be distinguished from other cation-pumping P-type ATPases, except from the cta3 Ca-ATPase of Schizosaccharomyces pombe.
Bañuelos
M A
MA
Departamento de Biotecnología, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Spain.
Rodríguez-Navarro
A
A
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics; D027682:Cation Transport Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011188:Potassium / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase
D027682:Cation Transport Proteins; C086375:ENA1 protein, S cerevisiae; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D012964:Sodium; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium