pH modulation of efflux pump activity of multi-drug resistant Escherichia coli

Protection during its passage and eventual colonization of the colon

Ana Martins, G. Spengler, Liliana Rodrigues, Miguel Viveiros, Jorge Ramos, Marta Martins, Isabel Couto, Séamus Fanning, Jean Marie Pagès, Jean Michel Bolla, J. Molnár, Leonard Amaral

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Background: Resistance Nodulation Division (RND) efflux pumps of Escherichia coli extrude antibiotics and toxic substances before they reach their intended targets. Whereas these pumps obtain their energy directly from the proton motive force (PMF), ATP-Binding Cassette (ABC) transporters, which can also extrude antibiotics, obtain energy from the hydrolysis of ATP. Because E. coli must pass through two pH distinct environments of the gastrointestinal system of the host, it must be able to extrude toxic agents at very acidic and at near neutral pH (bile salts in duodenum and colon for example). The herein described study examines the effect of pH on the extrusion of ethidium bromide (EB). Methodology/Principal Findings: E. coli AG100 and its tetracycline induced progeny AG100TET that over-expresses the acrAB efflux pump were evaluated for their ability to extrude EB at pH 5 and 8, by our recently developed semi-automated fluorometric method. At pH 5 the organism extrudes EB without the need for metabolic energy (glucose), whereas at pH 8 extrusion of EB is dependent upon metabolic energy. Phe-Arg β-naphtylamide (PAβN), a commonly assumed inhibitor of RND efflux pumps has no effect on the extrusion of EB as others claim. However, it does cause accumulation of EB. Competition between EB and PAβN was demonstrated and suggested that PAβN was preferentially extruded. A Km representing competition between PAβN and EB has been calculated. Conclusions/Significance: The results suggest that E. coli has two general efflux systems (not to be confused with a distinct efflux pump) that are activated at low and high pH, respectively, and that the one at high pH is probably a putative ABC transporter coded by msbA, which has significant homology to the ABC transporter coded by efrAB of Enterococcus faecalis, an organism that faces similar challenges as it makes its way through the toxic intestinal system of the host.

Original languageEnglish
Article numbere6656
JournalPLoS One
Volume4
Issue number8
DOIs
Publication statusPublished - Aug 17 2009

Fingerprint

Ethidium
Escherichia coli
colon
transporters
Colon
phenylalanylarginine
Modulation
Pumps
drugs
Pharmaceutical Preparations
ABC transporters
ATP-Binding Cassette Transporters
Poisons
extrusion
Extrusion
energy
nodulation
antibiotics
Anti-Bacterial Agents
Proton-Motive Force

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

pH modulation of efflux pump activity of multi-drug resistant Escherichia coli : Protection during its passage and eventual colonization of the colon. / Martins, Ana; Spengler, G.; Rodrigues, Liliana; Viveiros, Miguel; Ramos, Jorge; Martins, Marta; Couto, Isabel; Fanning, Séamus; Pagès, Jean Marie; Bolla, Jean Michel; Molnár, J.; Amaral, Leonard.

In: PLoS One, Vol. 4, No. 8, e6656, 17.08.2009.

Research output: Contribution to journalArticle

Martins, A, Spengler, G, Rodrigues, L, Viveiros, M, Ramos, J, Martins, M, Couto, I, Fanning, S, Pagès, JM, Bolla, JM, Molnár, J & Amaral, L 2009, 'pH modulation of efflux pump activity of multi-drug resistant Escherichia coli: Protection during its passage and eventual colonization of the colon', PLoS One, vol. 4, no. 8, e6656. https://doi.org/10.1371/journal.pone.0006656
Martins, Ana ; Spengler, G. ; Rodrigues, Liliana ; Viveiros, Miguel ; Ramos, Jorge ; Martins, Marta ; Couto, Isabel ; Fanning, Séamus ; Pagès, Jean Marie ; Bolla, Jean Michel ; Molnár, J. ; Amaral, Leonard. / pH modulation of efflux pump activity of multi-drug resistant Escherichia coli : Protection during its passage and eventual colonization of the colon. In: PLoS One. 2009 ; Vol. 4, No. 8.
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AU - Ramos, Jorge

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AU - Couto, Isabel

AU - Fanning, Séamus

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