Deletion of the major Escherichia coli multidrug transporter AcrB reveals transporter plasticity and redundancy in bacterial cells

PLoS One. 2019 Jun 28;14(6):e0218828. doi: 10.1371/journal.pone.0218828. eCollection 2019.

Abstract

Multidrug Transporters (MDTs) are major contributors to the acquisition and maintenance of Antimicrobial Resistance (AMR), a growing public health threat of broad concern. Despite the large number of MDTs, the overwhelming majority of the studies performed thus far in Gram-negative bacteria emphasize the supremacy of the AcrAB-TolC complex. To unveil the potential role of other MDTs we studied the behavior of a null AcrB Escherichia coli strain when challenged with chloramphenicol, a bacteriostatic antibiotic. We found that such a strain developed an extremely high-level of resistance to chloramphenicol, cross resistance to quinolones and erythromycin and displayed high levels of expression of the single component MFS transporter MdfA and multiple TolC-dependent transporters. The results suggest that the high versatility of the whole ensemble of transporters, the bacterial Effluxome, is an essential part of a strategy of survival in everchanging, at times noxious, environments. The concept of a functional Effluxome presents an alternative to the existing paradigms in the field and provides novel targets for the search for inhibitors of transporters as adjuvants of existing antibiotics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Outer Membrane Proteins / genetics
  • Chloramphenicol / pharmacology*
  • Drug Resistance, Multiple, Bacterial
  • Erythromycin / pharmacology
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / growth & development*
  • Escherichia coli Proteins / genetics*
  • Gene Deletion
  • Gene Expression Regulation, Bacterial / drug effects
  • Membrane Transport Proteins / genetics
  • Multidrug Resistance-Associated Proteins / genetics*
  • Quinolones / pharmacology
  • Spores, Bacterial

Substances

  • AcrB protein, E coli
  • Anti-Bacterial Agents
  • Bacterial Outer Membrane Proteins
  • Escherichia coli Proteins
  • Mdfa protein, E coli
  • Membrane Transport Proteins
  • Multidrug Resistance-Associated Proteins
  • Quinolones
  • tolC protein, E coli
  • Erythromycin
  • Chloramphenicol

Grants and funding

This research was funded by Grant A1004 from the Rosetrees Trust to SS and Grant 143/16 from the Israel Science Foundation to SS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.