title: Multidrug resistance transporters Snq2p and Pdr5p mediate caffeine efflux in Saccharomyces cerevisiae.
abstract: SNQ2 was identified as a caffeine-resistance gene by screening a genomic library of Saccharomyces cerevisiae in a multicopy vector YEp24. SNQ2 encodes an ATP-binding cassette transporter and is highly homologous to PDR5. Multicopy of PDR5 also conferred resistance to caffeine, while its resistance was smaller than that of SNQ2. Residual caffeine contents were analyzed after transiently exposing cells to caffeine. The ratios of caffeine contents were 21.3 ± 8.8% (YEp24-SNQ2) and 81.9 ± 8.7% (YEp24-PDR5) relative to control (YEp24, 100%). In addition, multicopies of SNQ2 or PDR5 conferred resistance to rhodamine 6G (R6G), which was widely used as a substrate for transport assay. R6G was exported by both transporters, and their efflux activities were inhibited by caffeine with half-maximal inhibitory concentrations of 5.3 ± 1.9 (YEp24-SNQ2) and 17.2 ± 9.6 mM (YEp24-PDR5). These results demonstrate that Snq2p is a more functional transporter of caffeine than Pdr5p in yeast cells.
authors: a Graduate School of Life and Environmental Sciences , Kyoto Prefectural University , Kyoto , Japan.
authors: Yoshiyuki
authors: Y
authors: Tsujimoto
authors: Yoshihiro
authors: Y
authors: Shimizu
authors: Kazuya
authors: K
authors: Otake
authors: Tatsuya
authors: T
authors: Nakamura
authors: Ryutaro
authors: R
authors: Okada
authors: Toshitaka
authors: T
authors: Miyazaki
authors: Kunihiko
authors: K
authors: Watanabe
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D002110:Caffeine / Q000493:pharmacokinetics* / Q000494:pharmacology; D026141:Drug Resistance, Multiple, Fungal / Q000187:drug effects / Q000235:genetics*; D018628:Gene Dosage; D055786:Gene Knockout Techniques; D012235:Rhodamines / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; C092438:PDR5 protein, S cerevisiae; D012235:Rhodamines; C101797:SNQ2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C026188:rhodamine 6G; D002110:Caffeine
keywords: ATP-binding cassette transporter; caffeine; rhodamine 6G