title: Alkylrhodamines enhance the toxicity of clotrimazole and benzalkonium chloride by interfering with yeast pleiotropic ABC-transporters.
abstract: ABC-transporters with broad substrate specificity are responsible for pathogenic yeast resistance to antifungal compounds. Here we asked whether highly hydrophobic chemicals with delocalized positive charge can be used to overcome the resistance. Such molecules efficiently penetrate the plasma membrane and accumulate inside the cells. We reasoned that these properties can convert an active efflux of the compounds into a futile cycle thus interfering with the extrusion of the antibiotics. To test this, we studied the effects of several alkylated rhodamines on the drug resistance of yeast Saccharomyces cerevisiae We found that octylrhodamine synergetically increases toxicity of Pdr5p substrate-clotrimazole, while the others were less effective. Next, we compared the contributions of three major pleiotropic ABC-transporters (Pdr5p, Yor1p, Snq2p) on the accumulation of the alkylated rhodamines. While all of the tested compounds were extruded by Pdr5p, Yor1p and Snq2p showed narrower substrate specificity. Interestingly, among the tested alkylated rhodamines, inactivation of Pdr5p had the strongest effect on the accumulation of octylrhodamine inside the cells, which is consistent with the fact that clotrimazole is a substrate of Pdr5p. As alkylated rhodamines were shown to be non-toxic on mice, our study makes them potential components of pharmacological antifungal compositions.
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskiye Gory 1-40, Moscow 119991, Russia knorre@belozersky.msu.ru.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Knorre
authors.affiliation: Faculty of Bioengineering and Bioinformatics, Moscow State University, Leninskiye Gory 1-73, Moscow 119991, Russia.
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Besedina
authors.affiliation: Faculty of Bioengineering and Bioinformatics, Moscow State University, Leninskiye Gory 1-73, Moscow 119991, Russia.
authors.forename: Iuliia E
authors.initials: IE
authors.lastname: Karavaeva
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskiye Gory 1-40, Moscow 119991, Russia.
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Smirnova
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskiye Gory 1-40, Moscow 119991, Russia.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Markova
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskiye Gory 1-40, Moscow 119991, Russia Institute of Mitoengineering, Moscow State University, Leninskiye Gory 1, Moscow 119991, Russia.
authors.forename: Fedor F
authors.initials: FF
authors.lastname: Severin
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors*; D000935:Antifungal Agents / Q000494:pharmacology*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D003022:Clotrimazole / Q000494:pharmacology*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000378:metabolism*; D050296:Microbial Viability / Q000187:drug effects; D012235:Rhodamines / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D001548:Benzalkonium Compounds; D004791:Enzyme Inhibitors; D012235:Rhodamines; D003022:Clotrimazole
keywords: Pdr5p; antifungal; futile cycle; multiple drug resistance; synergy; yeast