Isolation and characterization of the Saccharomyces cerevisiae SUT1 gene involved in sterol uptake.

A new gene (SUT1) of Saccharomyces cerevisiae, implicated in sterol uptake, was isolated from a yeast genomic library constructed in a high-copy-number vector by virtue of conferring resistance to fenpropimorph in medium supplemented with ergosterol. The high expression of SUT1 in sterol auxotrophic mutant strains alleviates the requirement for accessory mutations affecting heme biosynthesis and allows sterol uptake in aerobiosis. Measurements of [14C]cholesterol uptake confirmed that SUT1 is involved in sterol absorption. Within the 4.1-kb insert isolated, the functional gene was localised on a 1.7-kb DNA fragment. The nucleotide sequence encodes a predicted protein of 299 amino acids. Northern blot analysis revealed that SUT1 is a new member of the hypoxic gene family. Gene disruption showed that SUT1 is not essential for aerobic or anaerobic yeast growth.