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Imaging the electrostatic potential of transmembrane channels : atomic probe microscopy of OmpF porin

Philippsen, A. and Im, W. and Engel, A. and Schirmer, T. and Roux, B. and Muller, D. J.. (2002) Imaging the electrostatic potential of transmembrane channels : atomic probe microscopy of OmpF porin. Biophysical journal, Vol. 82, H. 3. pp. 1667-1676.

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Official URL: http://edoc.unibas.ch/dok/A5257655

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Abstract

The atomic force microscope (AFM) was used to image native OmpF porin and to detect the electrostatic potential generated by the protein. To this end the OmpF porin trimers from Escherichia coli was reproducibly imaged at a lateral resolution of approximately 0.5 nm and a vertical resolution of approximately 0.1 nm at variable electrolyte concentrations of the buffer solution. At low electrolyte concentrations the charged AFM probe not only contoured structural details of the membrane protein surface but also interacted with local electrostatic potentials. Differences measured between topographs recorded at variable ionic strength allowed mapping of the electrostatic potential of OmpF porin. The potential map acquired by AFM showed qualitative agreement with continuum electrostatic calculations based on the atomic OmpF porin embedded in a lipid bilayer at the same electrolyte concentrations. Numerical simulations of the experimental conditions showed the measurements to be reproduced quantitatively when the AFM probe was included in the calculations. This method opens a novel avenue to determine the electrostatic potential of native protein surfaces at a lateral resolution better than 1 nm and a vertical resolution of approximately 0.1 nm.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Former Organization Units Biozentrum > Structural Biology (Engel)
05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Schirmer)
UniBasel Contributors:Engel, Andreas H and Schirmer, Tilman
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Biophysical Society
ISSN:0006-3495
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2012 06:48
Deposited On:22 Mar 2012 13:18

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