Visualizing reaction pathways in photoactive yellow protein from nanoseconds to seconds.

Published

Journal Article

Determining 3D intermediate structures during the biological action of proteins in real time under ambient conditions is essential for understanding how proteins function. Here we use time-resolved Laue crystallography to extract short-lived intermediate structures and thereby unveil signal transduction in the blue light photoreceptor photoactive yellow protein (PYP) from Halorhodospira halophila. By analyzing a comprehensive set of Laue data during the PYP photocycle (forty-seven time points from one nanosecond to one second), we track all atoms in PYP during its photocycle and directly observe how absorption of a blue light photon by its p-coumaric acid chromophore triggers a reversible photocycle. We identify a complex chemical mechanism characterized by five distinct structural intermediates. Structural changes at the chromophore in the early, red-shifted intermediates are transduced to the exterior of the protein in the late, blue-shifted intermediates through an initial "volume-conserving" isomerization of the chromophore and the progressive disruption of hydrogen bonds between the chromophore and its surrounding binding pocket. These results yield a comprehensive view of the PYP photocycle when seen in the light of previous biophysical studies on the system.

Full Text

Duke Authors

Cited Authors

  • Ihee, H; Rajagopal, S; Srajer, V; Pahl, R; Anderson, S; Schmidt, M; Schotte, F; Anfinrud, PA; Wulff, M; Moffat, K

Published Date

  • May 17, 2005

Published In

Volume / Issue

  • 102 / 20

Start / End Page

  • 7145 - 7150

PubMed ID

  • 15870207

Pubmed Central ID

  • 15870207

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.0409035102

Language

  • eng

Conference Location

  • United States