Rta1, a yeast plasma membrane protein which confers resistance to fungicides
(2008)
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- Authors
- Supervisors
- Ghislain, Michel
- Abstract
- Research in the laboratory focuses on ABC transporter-mediated drug resistance in Saccharomyces cerevisiae. The yeast plasma membrane contains several ABC transporters which hydrolyze ATP to pump out a large variety of cytotoxic compounds. Gene expression of the pumps is activated by two closely-related transcriptional factors, Pdr1p and Pdr3p, via the binding to a regulatory motif (PDRE). Genome wide mRNA analysis has shown that the transcription of RTA1 was upregulated by Pdr1/3p. Overexpression of Rta1p leads to resistance to 7-aminocholesterol, a potent antifungal agent. The RTA1 promoter contains a PDRE motif. We showed that the activation of Rta1p by Pdr1/3p required PDRE, which is consistent with the effect of PDRE mutations on the decrease in RTA1-mediated 7 aminocholesterol resistance. We found that Pdr1p and Pdr3p activated Rta1p by binding to the RTA1 promoter. Yap1p, a transcriptional factor involved in the oxidative stress response, was also shown to bind to YRE motifs in the RTA1 promoter. However oxidative stress has no effect on Rta1p activity. The construction of a Green Fluorescent Protein- and His6-tagged versions allowed the detection of Rta1p in the plasma membrane. We purified Rta1p-His6 by affinity chromatography. Rta1p shows sequence identity with Rsb1p, a transporter of long-chain bases, such as phytosphingosine. We showed that overexpression of Rta1p increased the resistance to elevated concentrations of phytosphingosine. In contrast, no resistance to 7-aminocholesterol is observed upon overexpression of Rsb1p, indicating that the two proteins have distinct cellular functions. We also found that increased amounts of Rta1p increased resistance to nystatin in wild type cells and to itraconazole in cells lacking Pdr1p and the Pdr5p ABC-transporter. These results suggest that Rta1p is part of the pleiotropic drug resistance network and plays a role as a transporter or a receptor in linking growth to adaptation to cytotoxic compounds.
- Affiliations
Citations
Manente, M. (2008). Rta1, a yeast plasma membrane protein which confers resistance to fungicides. https://hdl.handle.net/2078.5/124075