Membrane Transport of Rhodamine 6G by the reconstituted multidrug resistance ABC transporter Pdr5 in Horizontal Lipid Bilayer

Abstract

Pdr5 is the most abundant ABC transporter in Saccharomyces cerevisiae and plays a key role in the pleiotropic drug resistance (PDR) network, actively preventing the sustained entry of a wide range of structurally diverse compounds into the cell. This transporter has been extensively studied in vivo, in plasma membrane vesicles, and more recently, after reconstitution into artificial membranes, making it a widely used model system for ABC transporter research. Recent structural studies of Pdr5 have provided new insights into its architecture and function. However, the precise molecular mechanisms underlying Pdr5-mediated membrane transport remain largely unresolved. In this study, we investigate the interaction of reconstituted Pdr5 in an artificial freestanding horizontal lipid bilayer system with Rhodamine 6G (R6G), a well-known Pdr5 substrate. We show that functionally reconstituted Pdr5 actively transports the R6G+ cation across the membrane in an ATP-dependent manner, moving it from one bulk phase to the other.