YEAST PUTATIVE TRANSCRIPTION FACTORS INVOLVED IN SALT TOLERANCE

Four putative yeast transcription factors (Hal6-9p) have been identifi ed which upon overexpression in multicopy plasmids increase sodium and lithium tolerance. This effect is mediated, at least in part, by incr eased expression of the Ena1p Na+/Li+ extrusion pump. Hal6p and Hal7p are bZIP proteins and their gene disruptions affected neither salt tol erance nor ENA1 expression. Hal8p and Hal9p are putative zinc fingers and their gene disruptions decreased both salt tolerance and ENA1 expr ession. Therefore, Hal8p and Hal9p, but not Hal6p and Hal7p, qualify a s transcriptional activators of ENA1 under physiological conditions. H al8p seems to mediate the calcineurin-dependent part of ENA1 expressio n. (C) 1998 Federation of European Biochemical Societies.