Candida drug resistance protein 1, a major multidrug XXXX binding cassette transporter of @entity5132 , translocates fluorescent phospholipids in a reconstituted system.

@entity1 @entity5897 @entity2380 @entity5132 @entity869 @entity7958 @entity855
@entity5132 drug resistance protein 1 ( @entity7958 ), an @entity855 -dependent drug efflux pump, contributes to multidrug resistance in Candida-infected immunocompromised @entity1 . Previous cell-based assays suggested that @entity7958 also acts as a phospholipid translocator. To investigate this, we reconstituted purified @entity7958 into sealed membrane vesicles. Comparison of the ATPase activities of sealed and permeabilized proteoliposomes indicated that @entity7958 was asymmetrically reconstituted such that approximately 70% of the molecules had their @entity855 binding sites accessible to the extravesicular space. Fluorescent glycerophospholipids were incorporated into the outer leaflet of the proteoliposomes, and their transport into the inner leaflet was tracked with a quenching assay using membrane-impermeant dithionite. We observed @entity855 -dependent transport of the fluorescent lipids into the inner leaflet of the vesicles. With approximately 6 molecules of @entity7958 per vesicle on average, the half-time to reach the maximal extent of transport was approximately 15 min. Transport was reduced in vesicles reconstituted with @entity7958 variants with impaired ATPase activity and could be competed out to different levels by a molar excess of drugs such as @entity2380 and @entity5897 that are known to be effluxed by @entity7958 . Transport was not affected by @entity869 , a compound that is not effluxed by @entity7958 . Our results suggest a direct link between the ability of @entity7958 to translocate fluorescent phospholipids and efflux drugs. We note that only a few members of the ABC superfamily of Candida have a well-defined role as drug exporters; thus, lipid translocation mediated by @entity7958 could reflect its cellular function.
