Biophysics Journal Club

Hidden dynamics in the unfolding of individual bacteriorhodopsin proteins

Wednesday, 14 June 2017 12:00PM PDT
Biophysics Journal Club
Mike Kirkness
SFU Physics
Hidden dynamics in the unfolding of individual bacteriorhodopsin proteins
Jun 14, 2017 at 12PM


Hao Yu, Matthew G. W. Siewny, Devin T. Edwards, Aric W. Sanders, Thomas T. Perkins
Science 355, 945-950 – Published 3 March 2017

Protein folding occurs as a set of transitions between structural states within an energy landscape. An oversimplified view of the folding process emerges when transiently populated states are undetected because of limited instrumental resolution. Using force spectroscopy optimized for 1-microsecond resolution, we reexamined the unfolding of individual bacteriorhodopsin molecules in native lipid bilayers. The experimental data reveal the unfolding pathway in unprecedented detail. Numerous newly detected intermediates—many separated by as few as two or three amino acids—exhibited complex dynamics, including frequent refolding and state occupancies of <10 ms. Equilibrium measurements between such states enabled the folding free-energy landscape to be deduced. These results sharpen the picture of the mechanical unfolding of membrane proteins and, more broadly, enable experimental access to previously obscured protein dynamics.