SmdAB, a heterodimeric ABC-Type multidrug efflux pump, in Serratia marcescens |
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Authors: | Matsuo Taira Chen Jing Minato Yusuke Ogawa Wakano Mizushima Tohru Kuroda Teruo Tsuchiya Tomofusa |
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Affiliation: | Department of Genome Applied Microbiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Tsushima, Okayama, 700-8530, Japan. |
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Abstract: | We cloned genes, designated smdAB, that encode a multidrug efflux pump from the chromosomal DNA of clinically isolated Serratia marcescens NUSM8906. For cells of the drug-hypersensitive strain Escherichia coli KAM32 harboring a recombinant plasmid carrying smdAB, structurally unrelated antimicrobial agents such as norfloxacin, tetracycline, 4′,6-diamidino-2-phenylindole (DAPI), and Hoechst 33342 showed elevated MICs. The deduced amino acid sequences of both SmdA and SmdB exhibited similarities to the sequences of ATP-binding cassette (ABC)-type multidrug efflux pumps. The efflux of DAPI and Hoechst 33342 from E. coli cells expressing SmdAB was observed, and the efflux activities were inhibited by sodium o-vanadate, which is a well-known ATPase inhibitor. The introduction of smdA or smdB alone into E. coli KAM32 did not elevate the MIC of DAPI; thus, both SmdA and SmdB were required for function. These results indicate that SmdAB is probably a heterodimeric multidrug efflux pump of the ABC family in S. marcescens. |
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