Web Release Date: October 23,
A Molecular Movie at 1.8 Å Resolution Displays the Photocycle of Photoactive
Yellow Protein, a Eubacterial Blue-Light Receptor, from Nanoseconds to Seconds
rajer,
#
Department of Biochemistry and Molecular Biology, Consortium for Advanced Radiation Sources, and Institute for Biophysical Dynamics, The University of Chicago, 920 East 58th Street, Chicago, Illinois 60637, Institut de Biologie Structurale Jean-Pierre Ebel, UMR 9015, 41 Avenue Jules Horowitz, 38027 Grenoble Cedex 1, France, European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France, and Department of Microbiology, E. C. Slater Institute, BioCentrum, University of Amsterdam, Nieuwe Achtergracht 127, 1018 WS Amsterdam, The Netherlands
Received April 6, 2001
Revised Manuscript Received August 20, 2001
This paper contains enhanced objects
available on the Internet at http://pubs.acs.org.
Abstract:
The photocycle of the bacterial blue-light photoreceptor, photoactive yellow protein, was stimulated by illumination of single crystals by a 7 ns laser pulse. The molecular events were recorded at high resolution by time-resolved X-ray Laue diffraction as they evolved in real time, from 1 ns to seconds after the laser pulse. The complex structural changes during the photocycle at ambient temperature are displayed in a movie of difference electron density maps relative to the dark state. The step critical to entry into the photocycle is identified as flipping of the carbonyl group of the 4-hydroxycinnamic acid chromophore into an adjacent, hydrophobic environment rather than the concomitant isomerization about the double bond of the chromophore tail. The structural perturbation generated at the chromophore propagates throughout the entire protein as a light-induced "protein quake" with its "epicenter" at the carbonyl moiety of the chromophore.
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