Membrane fluidity affects functions of Cdr1p, a multidrug ABC transporter of Candida albicans

Earlier, we have shown that the overexpression of an ABC transporter, CDR1, is involved in the emergence of multidrug resistance in Candida albicans. In this study, we checked its function in vivo by expressing it in differen t isogenic Saccharomyces cerevisiae erg mutants, which accumulated various intermediates of the ergosterol biosynthesis and thus altered the membrane fluidity. Functions like the accumulation of rhodamine 123, beta-estradiol, fluconazole and floppase activity associated with Cdr1p were measured to a scertain their responses to an altered membrane phase. The floppase activit y appeared to be favoured by an enhanced membrane fluidity, while the efflu xing of substrates and Cdr1p's ability to confer multidrug resistance were significantly reduced. We demonstrate that only some of the functions of Cd r1p were affected by an altered lipid environment. (C) 1999 Federation of E uropean Microbiological Societies. Published by Elsevier Science B.V. All r ights reserved.