Volume 20, Issue 6 pp. 483-489
Research Article

Atomic force microscopy imaging and single molecule recognition force spectroscopy of coat proteins on the surface of Bacillus subtilis spore

Jilin Tang

Jilin Tang

Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria

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Daniela Krajcikova

Daniela Krajcikova

Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic

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Rong Zhu

Rong Zhu

Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria

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Andreas Ebner

Andreas Ebner

Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria

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Simon Cutting

Simon Cutting

School of Biological Sciences, Royal Holloway University of London, UK

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Hermann J. Gruber

Hermann J. Gruber

Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria

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Imrich Barak

Imrich Barak

Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovak Republic

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Peter Hinterdorfer

Corresponding Author

Peter Hinterdorfer

Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria

Institute of Biophysics, Johannes Kepler University of Linz, 4040 Linz, Austria.Search for more papers by this author
First published: 12 October 2007
Citations: 29

Paper presented as part of a special issue of papers from the ‘AFMBiomed conference, Barcelona 2007’.

Abstract

Coat assembly in Bacillus subtilis serves as a tractable model for the study of the self-assembly process of biological structures and has a significant potential for use in nano-biotechnological applications. In the present study, the morphology of B. subtilis spores was investigated by magnetically driven dynamic force microscopy (MAC mode atomic force microscopy) under physiological conditions. B. subtilis spores appeared as prolate structures, with a length of 0.6–3 µm and a width of about 0.5–2 µm. The spore surface was mainly covered with bump-like structures with diameters ranging from 8 to 70 nm. Besides topographical explorations, single molecule recognition force spectroscopy (SMRFS) was used to characterize the spore coat protein CotA. This protein was specifically recognized by a polyclonal antibody directed against CotA (anti-CotA), the antibody being covalently tethered to the AFM tip via a polyethylene glycol linker. The unbinding force between CotA and anti-CotA was determined as 55 ± 2 pN. From the high-binding probability of more than 20% in force–distance cycles it is concluded that CotA locates in the outer surface of B. subtilis spores. Copyright © 2007 John Wiley & Sons, Ltd.

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