Multidrug Transporters CaCdr1p and CaMdr1p of Candida albicans Display Different Lipid Specificities: both Ergosterol and Sphingolipids Are Essential for Targeting of CaCdr1p to Membrane Rafts

Abstract

In this study, we compared the effects of altered membrane lipid composition on the localization of two membrane drug transporters from different superfamilies of the pathogenic yeast Candida albicans. We demonstrated that in comparison to the major facilitator superfamily multidrug transporter CaMdr1p, ATP-binding cassette transporter CaCdr1p of C. albicans is preferentially localized within detergent-resistant membrane (DRM) microdomains called 'rafts.' Both CaCdr1p and CaMdr1p were overexpressed as green fluorescent protein (GFP)-tagged proteins in a heterologous host Saccharomyces cerevisiae, wherein either sphingolipid (⌬sur4 or ⌬fen1 or ⌬ipt1) or ergosterol (⌬erg24 or ⌬erg6 or ⌬erg4) biosynthesis was compromised. CaCdr1p-GFP, when expressed in the above mutant backgrounds, was not correctly targeted to plasma membranes (PM), which also resulted in severely impaired drug resistance. In contrast, CaMdr1p-GFP displayed no sorting defect in the mutant background and remained properly surface localized and displayed no change in drug resistance. Our data clearly show that CaCdr1p is selectively recruited, over CaMdr1p, to the DRM microdomains of the yeast PM and that any imbalance in the raft lipid constituents results in missorting of CaCdr1p.

The Effect of Plagiochin E Alone and in Combination with Fluconazole on the Ergosterol Biosynthesis of Candida albicans

“…CDR1-mediated drug resistance was susceptible to changes in membrane fluidity. 17,18) Our initial investigations showed that PLE can obviously reduce the expression of CDR1, 9) which may be influenced by imbalances in membrane lipid composition.…”

Lipidomics of Candida albicans biofilms reveals phase-dependent production of phospholipid molecular classes and role for lipid rafts in biofilm formation

“…In this regard, lipid rafts have been proposed to play important roles in polarization and compartmentalization of the plasma membrane (Wachtler & Balasubramanian, 2006), surface transport of plasma membrane ATPase (Toulmay & Schneiter, 2007), hyphal growth (Martin & Konopka, 2004), drug resistance (Hallstrom et al, 2001;Pasrija et al, 2008;Prasad et al, 2005;Thevissen et al, 2000) and localization of virulenceassociated proteins (Siafakas et al, 2006).…”

“…Although several studies have indicated important roles for lipid rafts in modulating fungal growth and pathogenesis (Hallstrom et al, 2001;Martin & Konopka, 2004;Pasrija et al, 2008;Prasad et al, 2005;Siafakas et al, 2006;Thevissen et al, 2000;Toulmay & Schneiter, 2007;Wachtler & Balasubramanian, 2006), their role in biofilm formation and associated drug resistance has not been investigated.…”

First Step of Glycosylphosphatidylinositol (GPI) Biosynthesis Cross-talks with Ergosterol Biosynthesis and Ras Signaling in Candida albicans

“…Although most of the ergosterol in the plasma membrane can be replaced by other sterol intermediates, there are some functions within the cell, such as cell division, that necessarily require some amount of ergosterol to be present (23). Furthermore, membrane integrity and composition are not only essential for the viability of the fungal cells but also influence the localization and functioning of several membrane-localized proteins (38,39). Unfortunately, with regular use, drug resistance against most antifungals has been observed FIGURE 9.…”