title: AAA ATPases regulate membrane association of yeast oxysterol binding proteins and sterol metabolism.
abstract: The yeast genome encodes seven oxysterol binding protein homologs, Osh1p-Osh7p, which have been implicated in regulating intracellular lipid and vesicular transport. Here, we show that both Osh6p and Osh7p interact with Vps4p, a member of the AAA (ATPases associated with a variety of cellular activities) family. The coiled-coil domain of Osh7p was found to interact with Vps4p in a yeast two-hybrid screen and the interaction between Osh7p and Vps4p appears to be regulated by ergosterol. Deletion of VPS4 induced a dramatic increase in the membrane-associated pools of Osh6p and Osh7p and also caused a decrease in sterol esterification, which was suppressed by overexpression of OSH7. Lastly, overexpression of the coiled-coil domain of Osh7p (Osh7pCC) resulted in a multivesicular body sorting defect, suggesting a dominant negative role of Osh7pCC possibly through inhibiting Vps4p function. Our data suggest that a common mechanism may exist for AAA proteins to regulate the membrane association of yeast OSBP proteins and that these two protein families may function together to control subcellular lipid transport.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Penghua
authors.initials: P
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hongzhe
authors.initials: H
authors.lastname: Li
authors.forename: Hai Kee
authors.initials: HK
authors.lastname: Chieu
authors.forename: Alan L
authors.initials: AL
authors.lastname: Munn
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Yang
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport; D004952:Esters / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011987:Receptors, Steroid / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D000098825:Oxysterol Binding Proteins
chemical_list: D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D004952:Esters; D050556:Fatty Acid-Binding Proteins; C000601950:Osh7 protein, S cerevisiae; D011987:Receptors, Steroid; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; C107528:VPS4 protein, S cerevisiae; D000098825:Oxysterol Binding Proteins; D000251:Adenosine Triphosphatases