Asymmetric droplet interface bilayers

J Am Chem Soc. 2008 May 7;130(18):5878-9. doi: 10.1021/ja802089s. Epub 2008 Mar 26.

Abstract

In cell membranes, the lipid compositions of the inner and outer leaflets differ. Therefore, a robust model system that enables single-channel electrical recording with asymmetric bilayers would be very useful. We and others recently developed the droplet interface bilayer (DIB), which is formed by connecting lipid monolayer-encased aqueous droplets submerged in an oil-lipid mixture. Here, we incorporate lipid vesicles of different compositions into aqueous droplets and immerse them in an oil bath to form asymmetric DIBs (a-DIBs). Both alpha-helical and beta-barrel membrane proteins insert readily into a-DIBs, and their activity can be measured by single-channel electrical recording. We show that the gating behavior of outer membrane protein G (OmpG) from Escherichia coli differs depending on the side of insertion in an asymmetric DIB with a positively charged leaflet opposing a negatively charged leaflet. The a-DIB system provides a general platform for studying the effects of bilayer leaflet composition on the behavior of ion channels and pores.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkanes / chemistry*
  • Bacterial Outer Membrane Proteins / chemistry
  • Escherichia coli Proteins / chemistry
  • Ion Channels / chemistry
  • Lipid Bilayers / chemistry*
  • Lipids / chemistry
  • Membrane Proteins / chemistry
  • Porins / chemistry
  • Solutions
  • Water / chemistry*

Substances

  • Alkanes
  • Bacterial Outer Membrane Proteins
  • Escherichia coli Proteins
  • Ion Channels
  • Lipid Bilayers
  • Lipids
  • Membrane Proteins
  • OmpG protein, E coli
  • Porins
  • Solutions
  • Water
  • n-hexadecane