Molecular resolution imaging of an antibiotic peptide in a lipid matrix

J Am Chem Soc. 2009 May 13;131(18):6439-44. doi: 10.1021/ja808180m.

Abstract

In this work, we show molecular resolution scanning tunneling microscopy (STM) images of gramicidin, a model antibacterial peptide, inserted into a phospholipid matrix. The resolution of the images is superior to that obtained in previous attempts to image gramicidin in a lipid environment using atomic force microscopy (AFM). This breakthrough has allowed visualization of individual peptide molecules surrounded by lipid molecules. We have observed several important features: the peptide molecules do not aggregate, the peptide molecules adopt a single conformation corresponding to a specific ion channel form, and the lipid molecules adjacent to the peptide molecules are systematically longer than those in the lipid matrix. These results constitute a new approach to obtain structural characteristics of antibiotic peptides in lipid assemblies that is necessary for the understanding of their biological activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry*
  • Gramicidin
  • Ion Channels / chemistry
  • Lipids / chemistry*
  • Membrane Microdomains / chemistry
  • Membranes, Artificial
  • Microscopy, Scanning Tunneling / methods*
  • Molecular Conformation
  • Peptides / chemistry*

Substances

  • Anti-Bacterial Agents
  • Ion Channels
  • Lipids
  • Membranes, Artificial
  • Peptides
  • Gramicidin