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Force-induced conformational change of bacteriorhodopsin
1M. E. Müller-Institute for Structural Biology Biozentrum, University of Basel, Switzerland.
Journal of Molecular Biology
|June 2, 1995
Summary
Atomic force microscopy reveals that the shape of bacteriorhodopsin molecules in purple membranes changes with applied force. Lower forces reveal a distinct two-domain structure, while higher forces show three protrusions.
Area of Science:
- Biophysics
- Structural Biology
- Microscopy
Background:
- Purple membranes contain bacteriorhodopsin, a crucial protein for energy transduction.
- Atomic force microscopy (AFM) is a powerful tool for visualizing molecular structures at the nanoscale.
Purpose of the Study:
- To investigate the effect of applied force on the cytoplasmic surface topography of bacteriorhodopsin.
- To understand the structural plasticity of bacteriorhodopsin in response to mechanical stimuli.
Main Methods:
- Imaging of purple membranes using atomic force microscopy (AFM).
- Systematic variation of the force applied by the AFM stylus during imaging.
Main Results:
- Bacteriorhodopsin molecular topography is force-dependent.
- At 300 pN, bacteriorhodopsin shows a two-domain structure.
- At 100 pN, trimers transform into structures with three protrusions, and protein height increases by 2 Å.
Conclusions:
- The observed structural changes suggest a reversible bending of the prominent cytoplasmic loop of bacteriorhodopsin.
- AFM force modulation provides insights into protein conformational dynamics.