Structural basis of the Escherichia coli outer membrane permeability

Nabil A. Amro, Lakshmi P. Kotra, Kapila Wadu-Mesthrige, Alexy Bulychev, Shahriar Mobashery, Gang-yu Liu

Research output: Chapter in Book/Report/Conference proceedingChapter


We have studied, using AFM, the structural basis of the outer membrane permeability for the bacterium E. coli. The surface of the bacteria is visualized with an unprecedented details. Our AFM images clearly reveal that the outer membrane exhibits protrusions, which correspond to patches of LPS containing hundreds to thousands of LPS molecules. The packing of the nearest neighbor patches is tight, and as such the LPS layer provides an effective permeability barrier for the Gram-negative bacteria. We have also studied the mechanism of their permeability increase upon metal depletion. Our AFM images reveal that LPS molecules are released from the boundaries of some patches during the initial EDTA treatment. Further metal depletion produces a very distinct structure at the outer membrane: appearance of irregularly shaped pits. The pits are likely formed as a result of liberation of LPS patches and lipoproteins, exposing areas of peptidoglycan surface. Our study has proven AFM to be a very useful technique in providing structural basis for the functions of organisms.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Number of pages15
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1999 Scanning and Force Microscopies for Biomedical Applications - San Jose, CA, USA
Duration: Jan 24 1999Jan 25 1999


OtherProceedings of the 1999 Scanning and Force Microscopies for Biomedical Applications
CitySan Jose, CA, USA

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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