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Conformational Ensembles from Experimental Data
and Computer Simulations
Poster Abstracts
38
5-POS
Board 5
Signal Transduction in Drosophila Cryptochrome Revealed by Experimentally Guided
Molecular Dynamics Simulations
Oskar Berntsson
1
, Ryan Rodriguez
2
, Erik Schleicher
2
, Sebastian Westenhoff
1
.
1
University of Gothenburg, Göteborg, Sweden,
2
University of Freiburg, Freiburg, Germany.
Cryptochromes are blue light photoreceptor proteins found in plants and animals. They are the
main photoreceptor in the circadian clocks of insects and plants and are also required for
magnetoreception in birds and insects. A flavin chromophore within the protein matrix is
responsible for the blue light sensitivity. Upon illumination an electron is transferred a series of
tryptophan residues to the chromophore, creating a long lived radical pair. Eventually the signal
is relayed through the protein, causing detachment of the carboxy terminus. Using a combination
of molecular dynamics simulations and time-resolved X-ray solution scattering we investigate
the signal transduction pathway in
Drosophila melanogaster
cryptochrome (
Dm
Cry). Our
unpublished data show that
Dm
Cry gets compressed within the first 300 ns following light
exposure. This compression lasts about 1 ms before the protein extends and the carboxy terminal
part of the protein detaches. Our analysis reveals how the protonation state and hydrogen
bonding of a conserved histidine residue relays the signal from the chromophore to the carboxy
terminus. This is one of the most comprehensive structural models for cryptochrome signal
transduction to date and it provides insights into the effect of blue light on the circadian cycle.