Conformational Ensembles from Experimental Data and Computer Simulations

Conformational Ensembles from Experimental Data and Computer Simulations

Poster Abstracts

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 Our unpublished data show that Dm Cry gets compressed within the first 300 ns following light exposure.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.

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