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Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
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Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System

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Functionally cloned pdrM from Streptococcus pneumoniae encodes a Na(+) coupled multidrug efflux pump

Kohei Hashimoto1, Wakano Ogawa, Toshihiro Nishioka

  • 1Department of Molecular Microbiology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Tsushima, Okayama, Japan.

Plos One
|April 5, 2013
PubMed

Insights

Streptococcus pneumoniae possesses a multidrug efflux pump, PdrM, which confers resistance to antibacterial agents by acting as a sodium-dependent drug antiporter. Other MATE-type genes in S. pneumoniae may have different physiological roles.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Multidrug efflux pumps are crucial bacterial self-defense mechanisms.
  • These pumps are categorized into five families: RND, SMR, MF, ABC, and MATE.
  • Understanding MATE-type pumps is vital for combating bacterial drug resistance.

Purpose of the Study:

  • To clone and characterize a MATE-type multidrug efflux pump from Streptococcus pneumoniae R6.
  • To investigate the substrate specificity and transport mechanism of the identified pump.
  • To explore other potential MATE-type genes in S. pneumoniae.

Main Methods:

  • Gene cloning and heterologous expression in E. coli KAM32.
  • Determination of minimum inhibitory concentrations (MICs) for various antibacterial agents.
  • Analysis of ion dependency (Na+, Li+) for substrate efflux.
  • Detection of mRNA expression using laboratory growth conditions.

Main Results:

  • Cloned MATE-type pump, designated PdrM, conferred resistance to norfloxacin, acriflavine, and DAPI.
  • PdrM functions as a Na+/drug antiporter, exhibiting Na+- or Li+-dependent efflux of acriflavine and DAPI.
  • Two additional MATE-type genes (spr1756, spr1877) were identified in S. pneumoniae but did not confer drug resistance.
  • mRNA expression of pdrM, spr1756, and spr1877 was detected in S. pneumoniae R6.

Conclusions:

  • PdrM is a novel Na+/drug antiporter in Streptococcus pneumoniae.
  • While spr1756 and spr1877 are expressed, they likely serve physiological roles unrelated to the tested drug resistance.
  • This study enhances the understanding of MATE-type efflux pumps and their diverse functions in bacteria.

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