title: A molecular movie at 1.8 A resolution displays the photocycle of photoactive yellow protein, a eubacterial blue-light receptor, from nanoseconds to seconds.
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.
authors.affiliation: 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, USA. renz@cars.uchicago.edu
authors.forename: Z
authors.initials: Z
authors.lastname: Ren
authors.forename: B
authors.initials: B
authors.lastname: Perman
authors.forename: V
authors.initials: V
authors.lastname: Srajer
authors.forename: T Y
authors.initials: TY
authors.lastname: Teng
authors.forename: C
authors.initials: C
authors.lastname: Pradervand
authors.forename: D
authors.initials: D
authors.lastname: Bourgeois
authors.forename: F
authors.initials: F
authors.lastname: Schotte
authors.forename: T
authors.initials: T
authors.lastname: Ursby
authors.forename: R
authors.initials: R
authors.lastname: Kort
authors.forename: M
authors.initials: M
authors.lastname: Wulff
authors.forename: K
authors.initials: K
authors.lastname: Moffat
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003198:Computer Simulation; D018360:Crystallography, X-Ray / Q000295:instrumentation / Q000379:methods*; D020607:Halorhodospira halophila / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry; D017440:Photoperiod; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D012996:Solutions; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D012996:Solutions; C050162:photoactive yellow protein, Bacteria; D010100:Oxygen