Involvement of Spt7p in vacuolar polyphosphate level of Saccharomyces cerevisiae

Saccharomyces cerevisiae became less sensitive to nickel by a defect of the SPT7 gene encoding a transcription factor. Initial rate of nickel uptake b y whole cells of a SPT7-negative mutant FY963 was nearly equal to that of t he parent strain FY61, and FY963 accumulated nickel about 1.7-fold of the v alue of FY61 when cultured in medium containing 0.1 mM NiCI2; most of which was sequestered into vacuoles. The pH gradient-driven nickel uptake by vac uolar membrane vesicles was not altered in FY963, but the amount of polypho sphate in vacuoles was highly elevated. Involvement of Spt7p in nickel deto xification through regulation of vacuolar polyphosphate level in S. cerevis iae was discussed. (C) 1999 Academic Press.