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Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
Bacteriorhodopsin folds into the membrane against an external force
Max Kessler1, Kay E Gottschalk, Harald Janovjak
1Chair of Applied Physics and Center for NanoScience, Ludwig-Maximilians Universität, Amalienstrasse 54, 80799 München, Germany.
Journal of Molecular Biology
|January 26, 2006
Summary
Researchers successfully controlled the refolding of single membrane proteins into their native state within the membrane using atomic force microscopy (AFM). This study quantifies the forces involved in protein folding, providing new insights into membrane protein mechanisms.
Area of Science:
- Biophysics
- Structural Biology
- Membrane Protein Folding
Background:
- Membrane proteins are vital for cellular function, yet their folding mechanisms remain poorly understood.
- Atomic force microscopy (AFM)-based single-molecule force spectroscopy has recently begun to map the energy landscape of protein folding.
Purpose of the Study:
- To investigate the controlled refolding of single membrane proteins into a lipid bilayer.
- To quantify the mechanical forces and energy barriers during the refolding process.
Main Methods:
- Partial unfolding and extraction of bacteriorhodopsin monomers from purple membrane using AFM.
- Controlled refolding by gradually lowering the AFM tip while recording folding forces.
- Subsequent unfolding to verify native state refolding.
Main Results:
- Demonstrated controlled refolding of individual bacteriorhodopsin monomers into the membrane.
- Observed helices being pulled into the membrane against significant external forces (tens of picoNewtons).
- Derived an upper limit for Gibbs free folding energy from mechanical work performed by helices.
Conclusions:
- Established a method for controlled refolding of membrane proteins in situ.
- Provided quantitative mechanical data on membrane protein folding pathways.
- Corroborated successful refolding into the native state through mechanical analysis.
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