Structural basis of the Escherichi coli outer-membrane permeability

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

doi:10.1117/12.350625

17 June 1999 Structural basis of the Escherichi coli outer-membrane permeability

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

Proceedings Volume 3607, Scanning and Force Microscopies for Biomedical Applications; (1999) https://doi.org/10.1117/12.350625
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

We have studied, using AFM, the structural basis of the outer membrane permeability for the bacterium E. col. 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 peptidoglacan surface. Our study has proven AFM to be a very useful technique in providing structural basis for the functions of organisms.

Citation Download Citation

Nabil A. Amro, Lakshmi P. Kotra, Kapila Wadu-Mesthrige, Alexy Bulychev, Shahriar Mobashery, and Gang-yu Liu "Structural basis of the Escherichi coli outer-membrane permeability", Proc. SPIE 3607, Scanning and Force Microscopies for Biomedical Applications, (17 June 1999); https://doi.org/10.1117/12.350625

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