Role of Snf1p in Regulation of Intracellular Sorting of the Lactose and Galactose Transporter Lac12p in Kluyveromyces lactis

Abstract

ABSTRACT The protein kinase Snf1/AMPK plays a central role in carbon and energy homeostasis in yeasts and higher eukaryotes. To work out which aspects of the Snf1-controlled regulatory network are conserved in evolution, the Snf1 requirement in galactose metabolism was analyzed in the yeast Kluyveromyces lactis . Whereas galactose induction was only delayed, K. lactis snf1 mutants failed to accumulate the lactose/galactose H + symporter Lac12p in the plasma membran,e as indicated by Lac12-green fluorescent protein fusions. In contrast to wild-type cells, the fusion protein was mostly intracellular in the mutant. Growth on galactose and galactose uptake could be restored by the KHT3 gene, which encodes a new transporter of the HXT subfamily of major facilitators These findings indicate a new role of Snf1p in regulation of sugar transport in K. lactis .