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Controlled unzipping of a bacterial surface layer with atomic force microscopy
D J Müller1, W Baumeister, A Engel
1M. E. Müller-Institute for Structural Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Summary
We used atomic force microscopy (AFM) to measure forces between proteins in Deinococcus radiodurans. Individual protein units were removed at 300 pN, revealing insights into bacterial pore stability.
Area of Science:
- Microbiology
- Biophysics
- Materials Science
Background:
- Deinococcus radiodurans possesses a unique hexagonally packed intermediate (HPI) layer crucial for its survival.
- Understanding the mechanical properties of the HPI layer is essential for deciphering its structural integrity and function.
Purpose of the Study:
- To investigate the interaction forces between individual protomers of the HPI layer.
- To correlate adhesion forces with structural changes at the single-molecule level.
- To determine the mechanical stability of bacterial pores.
Main Methods:
- High-resolution atomic force microscopy (AFM) imaging was employed to visualize the HPI layer.
- Force spectroscopy was utilized to measure the pulling forces required to detach individual protomers.
- Sequential unzipping experiments were performed on bacterial pores.
Main Results:
- Individual HPI protomers were detached at pulling forces of approximately 300 pN.
- The study successfully correlated adhesion forces with observed structural alterations in the HPI layer.
- It was possible to sequentially unzip entire bacterial pores, demonstrating the mechanical properties of the assembled structure.
Conclusions:
- The combined AFM imaging and force spectroscopy approach provides a powerful method for studying the mechanical stability of supramolecular structures.
- This technique allows for the analysis of intramolecular forces at the single-molecule level.
- The findings offer new insights into the structural mechanics of bacterial cell envelopes.