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Proc Natl Acad Sci U S A. 2019 Sep 4. pii: 201907875. doi: 10.1073/pnas.1907875116. [Epub ahead of print]

Chemical and structural analysis of a photoactive vertebrate cryptochrome from pigeon.

Author information

1
Department of Chemistry, Southern Methodist University, Dallas, TX 75275.
2
Center for Drug Discovery, Design, and Delivery, Southern Methodist University, Dallas, TX 75275.
3
Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390.
4
Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390.
5
Department of Chemistry, University of Oxford, OX1 3QZ Oxford, United Kingdom.
6
Institute for Biology and Environmental Sciences, Carl von Ossietzky University of Oldenburg, DE-26111 Oldenburg, Germany.
7
Research Center for Neurosensory Sciences, University of Oldenburg, DE-26111 Oldenburg, Germany.
8
Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390; joseph.takahashi@utsouthwestern.edu.

Abstract

Computational and biochemical studies implicate the blue-light sensor cryptochrome (CRY) as an endogenous light-dependent magnetosensor enabling migratory birds to navigate using the Earth's magnetic field. Validation of such a mechanism has been hampered by the absence of structures of vertebrate CRYs that have functional photochemistry. Here we present crystal structures of Columba livia (pigeon) CRY4 that reveal evolutionarily conserved modifications to a sequence of Trp residues (Trp-triad) required for CRY photoreduction. In ClCRY4, the Trp-triad chain is extended to include a fourth Trp (W369) and a Tyr (Y319) residue at the protein surface that imparts an unusually high quantum yield of photoreduction. These results are consistent with observations of night migratory behavior in animals at low light levels and could have implications for photochemical pathways allowing magnetosensing.

KEYWORDS:

cryptochromes; magnetoreception; photobiology

PMID:
31484780
DOI:
10.1073/pnas.1907875116
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Conflict of interest statement

The authors declare no conflict of interest.

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