European Biophysics Journal

, Volume 34, Issue 5, pp 389–395 | Cite as

The effects of parabens on the mechanosensitive channels of E. coli

Article

Abstract

Parabens are alkyl esters of p-hydroxybenzoic acid used as preservatives in a wide range of food, pharmaceutical, and cosmetic products (Soni et al. Food Chem. Toxicol. 39:513–532, 2001). Despite their common use for over 50 years, their mechanism of action is still unclear. In this study we examined the effects of ethyl and propyl paraben, on gating of the E. coli mechanosensitive channel of large conductance (MscL) reconstituted into azolectin liposomes. We found that propyl and ethyl paraben spontaneously activate MscL. Moreover, the addition of propyl paraben caused an increase in MscL activity and the lowering of p1/2, the pressure at which the MscL was opened 50% of the time, the ΔGo, the free energy required to open the MscL, and the parameter α, which describes the channel sensitivity to pressure. In addition, in silico studies showed that propyl paraben binds to the channel gate of the MscL. The mechanosensitive channel of small conductance was also found to be spontaneously activated by parabens. In summary, our study indicates that one of the previously unidentified mechanisms of action of parabens as antimicrobial agents is via an interaction with the mechanosensitive channels to upset the osmotic gradients in bacteria.

Keywords

Mechanosensitive channels Parabens Mechanosensitive channel of large conductance Mechanosensitive channel of small conductance p-Hydroxybenzoic acid 

Abbreviations

EDTA

Ethylenediaminetetraacetic acid

HEPES

N-(2-Hydroxyethyl)piperazine-N′-ethanesulfonic acid

MS

Mechanosensitive

MscL

Mechanosensitive channel of large conductance

MscS

Mechanosensitive channel of small conductance

Notes

Acknowledgements

This work was supported by the Australian Research Council and a UWA Postgraduate Award to T.N.

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Copyright information

© EBSA 2005

Authors and Affiliations

  • Thom Nguyen
    • 1
  • Brian Clare
    • 1
  • Wei Guo
    • 1
  • Boris Martinac
    • 2
  1. 1.School of Medicine and Pharmacology, QEII Medical CentreThe University of Western AustraliaCrawleyAustralia
  2. 2.School of Biomedical SciencesThe University of QueenslandBrisbaneAustralia

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