Transcriptional profiling identifies two members of the ATP-binding cassette transporter superfamily required for sterol uptake in yeast.
In contrast to lipoprotein-mediated sterol uptake, free sterol influx by eukaryotic cells is poorly understood. To identify components of non-lipoprotein-mediated sterol uptake, we utilized strains of Saccharomyces cerevisiae that accumulate exogenous sterol due to a neomorphic mutation in the transcription factor, UPC2. Two congenic upc2-1 strains, differing quantitatively in aerobic sterol uptake due to a modifying mutation in the HAP1 transcription factor, were compared using DNA microarrays. We identified 9 genes as responsive to UPC2 that were also induced under anaerobiosis, when sterol uptake is essential. Deletion mutants in these genes were assessed for sterol influx in the upc2-1 background. UPC2 itself was up-regulated under these conditions and was required for aerobic sterol influx. Deletion of the ATP-binding cassette transporters YOR011w (AUS1) or PDR11, or a putative cell wall protein encoded by DAN1, significantly reduced sterol influx. Sodium azide and vanadate inhibited sterol uptake, consistent with the participation of ATP-binding cassette transporters. We hypothesized that the physiological role of Aus1p and Pdr11p is to mediate sterol uptake when sterol biosynthesis is compromised. Accordingly, expression of AUS1 or PDR11 was required for anaerobic growth and sterol uptake. We proposed similar molecules may be important components of sterol uptake in all eukaryotes.
Wilcox
Lisa J
LJ
Institute of Human Nutrition and Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Balderes
Dina A
DA
Wharton
Brook
B
Tinkelenberg
Arthur H
AH
Rao
Govinda
G
Sturley
Stephen L
SL
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000483:Alleles; D015152:Blotting, Northern; D002455:Cell Division; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017353:Gene Deletion; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D016366:Open Reading Frames; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000235:genetics*; D019810:Sodium Azide / Q000494:pharmacology; D013261:Sterols / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014638:Vanadates / Q000494:pharmacology
D018528:ATP-Binding Cassette Transporters; C466994:AUS1 protein, S cerevisiae; D018076:DNA, Complementary; C466995:PDR11 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; D014638:Vanadates; D012313:RNA; D000255:Adenosine Triphosphate; D019810:Sodium Azide