SmdAB, a heterodimeric ABC-type multidrug efflux pump, in Serratia marcescens

Taira Matsuo, Jing Chen, Yusuke Minato, Wakano Ogawa, Tohru Mizushima, Teruo Kuroda, Tomofusa Tsuchiya

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)648-654
Number of pages7
JournalJournal of Bacteriology
Issue number2
Publication statusPublished - 2008 Jan
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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