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A linkage between SmeIJK efflux pump, cell envelope integrity, and σE-mediated envelope stress response in

Yi-Wei Huang1, Rung-Shiuan Liou1, Yi-Tsung Lin2

  • 1Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan.

Plos One
|November 13, 2014
PubMed

Insights

The SmeIJK efflux pump in Stenotrophomonas maltophilia maintains cell envelope integrity and aids in stress response, contributing to intrinsic antibiotic resistance. This study reveals its crucial physiological role beyond just pumping out drugs.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Physiology

Background:

  • Resistance Nodulation Division (RND) efflux pumps contribute to multidrug resistance in Gram-negative bacteria.
  • Constitutive expression of some RND pumps suggests roles beyond antibiotic efflux, potentially related to cell physiology.

Purpose of the Study:

  • To investigate the role of the SmeIJK efflux pump in Stenotrophomonas maltophilia's antimicrobial resistance, envelope integrity, and σE-mediated envelope stress response (ESR).

Main Methods:

  • Assessed SmeIJK's involvement in intrinsic resistance to specific antibiotics.
  • Compared a smeIJK deletion mutant with wild-type S. maltophilia KJ regarding growth, sensitivity to membrane-damaging agents (MDAs), and ESR activation.
  • Investigated SmeIJK expression induction by MDAs or surfactants in an σE-dependent manner.

Main Results:

  • SmeIJK contributes to intrinsic resistance against aminoglycosides and leucomycin in S. maltophilia.
  • Deletion of smeIJK resulted in growth defects, increased sensitivity to MDAs, and activated σE-mediated ESR.
  • SmeIJK expression is induced by MDAs and surfactants via an σE-dependent pathway.

Conclusions:

  • SmeIJK plays a vital physiological role in maintaining cell envelope integrity and managing the σE-mediated ESR in S. maltophilia, independent of antibiotic efflux.
  • The constitutive expression of SmeIJK is necessary for protecting the bacteria from envelope stress, which also confers intrinsic antibiotic resistance.

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