title: Different binding sites of bovine organic anion-transporting polypeptide1a2 are involved in the transport of different fluoroquinolones.
abstract: Because of their wide distribution and capability of transporting a large variety of compounds, organic anion-transporting polypeptides (OATPs) have been extensively recognized as crucial players in absorption, distribution, and excretion of various drugs. OATP1A2 was the first cloned human OATP and has been found to transport wide range of endogenous and exogenous compounds. Bovine Oatp1a2 (bOatp1a2) shares high homology with human OATP1A2 and is considered the functional ortholog of the latter. Previous study in our laboratory demonstrated that bOatp1a2 transport of estrone-3-sulfate (ES) exhibited biphasic saturation kinetics. In the present study, we investigated the transport function of bOatp1a2 for four different quinolone antibacterial agents (enrofloxacin, levofloxacin, norfloxacin, and ciprofloxacin) and found that all the tested fluoroquinolones can be transported by bOatp1a2. Further studies showed that different binding sites are responsible for the transport of different fluoroquinolones. Both ciprofloxacin and norfloxacin exhibited biphasic saturation kinetics. The Kms of the high- and low-affinity components for ciprofloxacin were 3.80 ± 0.85 μM and 182 ± 31 μM, respectively, while those for norfloxacin were 24.7 ± 0.1 μM and 393 ± 79 μM, respectively. Enrofloxacin and levofloxacin showed an inhibitory effect on the uptake of only the high concentration of ES and thus may be transported by the low-affinity site for ES. Interestingly, enrofloxacin and levofloxacin demonstrated an activation effect on ES uptake at the high-affinity binding site. These results suggested that multiple binding sites within the structure of bOatp1a2 may be responsible for the uptake of different quinolone antimicrobial agents.
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Jifeng
authors.initials: J
authors.lastname: Deng
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Jiujiu
authors.initials: J
authors.lastname: Huang
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Yongxue
authors.initials: Y
authors.lastname: Sun
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.).
authors.forename: Renke
authors.initials: R
authors.lastname: Dai
authors.affiliation: College of Life Science and Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms (Y.X., X.L., J.H., M.H.) and College of Veterinary Medicine (Y.S.), South China Agricultural University, Guangzhou, China; and School of Bioscience & Bioengineering, South China University of Technology, Guangzhou, China (J.D., R.D.) mh2788@scau.edu.cn.
authors.forename: Mei
authors.initials: M
authors.lastname: Hong
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology*; D001692:Biological Transport / Q000502:physiology*; D002417:Cattle; D002460:Cell Line; D024841:Fluoroquinolones / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007700:Kinetics; D027361:Organic Anion Transporters / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D027361:Organic Anion Transporters