Cloning and expression of two genes coding for sodium pumps in the salt-tolerant yeast Debaryomyces hansenii

Two genes encoding Na+-ATPases from Debaryomyces hansenii were cloned and s equenced. The genes, designated ENA1 from D. hansenii (DhENA1) and DhENA2, exhibited high homology with the corresponding genes from Schwanniomyces oc cidentalis. DhENA1 was expressed in the presence of high Na+ concentrations , while the expression of DhENA2 also required high pH. A mutant of Sacchar omyces cerevisiae lacking the Na+ efflux systems and sensitive to Na+, when transformed with DhENA1 or DhENA2, recovered Na+ tolerance and also the ab ility to extrude Na+.