High-speed atomic force microscopy shows dynamic molecular processes in photoactivated bacteriorhodopsin

Area of Science:

• Biophysics
• Structural Biology
• Microscopy

Background:

• Protein conformational changes are vital for biological processes.
• Visualizing these dynamic structural changes under physiological conditions is challenging.

Purpose of the Study:

• To demonstrate high-speed atomic force microscopy (HS-AFM) for visualizing dynamic protein conformational changes.
• To investigate the light-induced structural dynamics of bacteriorhodopsin.

Main Methods:

• High-speed atomic force microscopy (HS-AFM) was employed to capture high-resolution movies.
• The study focused on a light-driven proton pump, bacteriorhodopsin.

Main Results:

• HS-AFM movies revealed light-induced contact between cytoplasmic portions of bacteriorhodopsin monomers and adjacent trimers.
• Bacteriorhodopsin interactions in transient assemblies showed positive and negative cooperative effects in decay kinetics.
• The turnover rate of the bacteriorhodopsin photocycle remained constant on average, regardless of light intensity.

Conclusions:

• High-resolution visualization using HS-AFM is a powerful technique for studying biomolecular processes.
• The findings provide insights into the cooperative mechanisms governing bacteriorhodopsin photocycle dynamics.