Abstract
September 13, 2006, 4:30 pm
Cornell University Biophysics Colloquium

“To catch a Photon: Structure and conformational dynamics of the
bacterial photoreceptor PYP”

Ulrich Genick
Assistant Professor of Biochemistry
Brandeis University
Website

The small bacterial photoreceptor PYP is a structural biophysicist's dream come true. The exceptional quality of PYP crystals (diffraction to 0.82 Ang. res.) and the ability to trigger and monitor PYP's light-sensing reaction in the crystal allow us to ask experimental questions about the interplay of protein structure, function and dynamics that are difficult, if not impossible, to ask in most other experimental systems.

In the talk I will introduce PYP as an experimental system including our own x-ray crystallographic work on the structural changes during the PYP photocycle. In the second half of the talk I will discuss recent work, in which we try to understand the role of protein dynamics and conformational variability in PYP's ability to sense light with high efficiency.

In this recent work we made two surprising observations: a) The dynamics of the PYP active site anticipates the reaction trajectory of the light-driven chromophore isomerization reaction.
b) Structural differences on the scale of a few picometers distinguish highly active from photochemically inert states of PYP.

Return to Biophysics Colloquia page.