Structure-functional Relationship Of Candida Albicans Multidrug Resistance Protein

Abstract To investigate the role of transmembrane segments (TMS) of Candidaalbicans drug resistance protein (Cdr1p) in drug extrusion. We replaced the amino acids of TMS1, TMS2, TMS4, TMS6, TMS8, and TMS10 of Cdrlp with that of corresponding to the same sites of Cdr3p by site-directed mutagenesis. The saccharomyces cerevisiae ADl-8u" strain was used to express the wild-type and mutant proteins. The strains expressing mutant variants were determined for the alterations in the susceptibilities to drugs, the efflux of Rhodamine 6G (R6G), and the competition assays of azole antifungal drugs and R6G The results showed L776F, M1246Y and A1324L were more sensitive to azole antifungal drugs than the wild type strain. I514L, L563F L776F, F1239L, M1246Y and A1324L induced the decreases of extracellular concentrations of R6G The azole antifungal drugs inhibited the efflux of R6G in the wild type strain, while it was different in variants of Cdrlp. Our study for the first time suggested that TMS1, TMS4, TMS8, and TMS10 were also the major drug binding sites, and provided insight into the important amino acid residues.