European Biophysics Journal

, 38:415

Concentration dependent effect of GsMTx4 on mechanosensitive channels of small conductance in E. coli spheroplasts

Authors

  • Annette C. Hurst
    • Molecular Biophysics Laboratory, School of Biomedical SciencesUniversity of Queensland
  • Philip A. Gottlieb
    • Department of Physiology and BiophysicsSUNY at Buffalo
    • Molecular Biophysics Laboratory, School of Biomedical SciencesUniversity of Queensland
    • The Victor Chang Cardiac Research InstituteLowy Packer Building
Original Paper

DOI: 10.1007/s00249-008-0386-9

Cite this article as:
Hurst, A.C., Gottlieb, P.A. & Martinac, B. Eur Biophys J (2009) 38: 415. doi:10.1007/s00249-008-0386-9

Abstract

The spider peptide GsMTx4, at saturating concentration of 5 μM, is an effective and specific inhibitor for stretch-activated mechanosensitive (MS) channels found in a variety of eukaryotic cells. Although the structure of the peptide has been solved, the mode of action remains to be determined. Because of its amphipathic structure, the peptide is proposed to interact with lipids at the boundaries of the MS channel proteins. In addition, GsMTx4 has antimicrobial effects, inhibiting growth of several species of bacteria in the range of 5–64 μM. Previous studies on prokaryotic MS channels, which serve as model systems to explore the principle of MS channel gating, have shown that various amphipathic compounds acting at the protein–lipid interface affect MS channel gating. We have therefore analyzed the effect of different concentrations of extracellular GsMTx4 on MS channels of small conductance, MscS and MscK, in the cytoplasmic membrane of wild-type E. coli spheroplasts using the patch-clamp technique. Our study shows that the peptide GsMTx4 exhibits a biphasic response in which peptide concentration determines inhibition or potentiation of activity in prokaryotic MS channels. At low peptide concentrations of 2 and 4 μM the gating of the prokaryotic MS channels was hampered, manifested by a decrease in pressure sensitivity. In contrast, application of peptide at concentrations of 12 and 20 μM facilitated prokaryotic MS channel opening by increasing the pressure sensitivity.

Keywords

MscS MscK Patch-clamp Grammostola peptide Amphipath Biphasic response

Abbreviations

MS

Mechanosensitive channels

WT

Wild-type

SACs

Stretch-activated channels

MscL

Mechanosensitive channel of large conductance

MscS

Small conductance

MscK

Small conductance, K+ dependent

MscM

Mini-conductance

POPG

Palmitoyloleoylphosphoglycerol

POPC

Palmitoyloleoylphosphocholine

PE

Phosphoethanolamine

PG

Phosphoglycerol

PC

Pressure cycle

Copyright information

© European Biophysical Societies' Association 2008