A Compass at Weak Magnetic Fields Using Thymine Dimer Repair
Abstract
How birds sense the variations in Earth's magnetic field for navigation is poorly understood, although cryptochromes, proteins homologous to photolyases, have been proposed to participate in this magnetic sensing. Here, in electrochemical studies with an applied magnetic field, we monitor the repair of cyclobutane pyrimidine dimer lesions in duplex DNA by photolyase, mutants of photolyase, and a modified cryptochrome. We find that the yield of dimer repair is dependent on the strength and angle of the applied magnetic field even when using magnetic fields weaker than 1 gauss. This high sensitivity to weak magnetic fields depends upon a fast radical pair reaction on the thymines leading to repair. These data illustrate chemically how cyclobutane pyrimidine dimer repair may be used in a biological compass informed by variations in Earth's magnetic field.
Additional Information
© 2018 American Chemical Society. This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: January 4, 2018; Publication Date (Web): March 7, 2018. We are grateful to the NIH (GM061077 to J.K.B. and GM074813 to D.Z.) for their financial support. E.C.M.T. appreciates the Croucher Foundation for a postdoctoral fellowship. T.J.Z. is an NSF fellow (DGE-1144469) and would like to thank them for financial support of this research. We thank Jennifer Buz and Joseph Kirschvink for discussion and aid with SQUID measurements. We thank Mona Shahgholi and the Caltech MultiUser Mass Spectrometry Lab for help conducting mass spectrometry experiments. We dedicate this manuscript to Nicholas J. Turro, whose studies on radical pair reactions in weak fields stimulated this work. Author Contributions: T.J.Z. and J.K.B. designed the experiments. T.J.Z. performed most of the experiments. E.C.M.T. performed gel shift experiments, some electrochemistry experiments, DNA digestion, HPLC, and MS product analysis. D.Z. produced and purified all proteins as well as provided guidance for proper protein handling. T.J.Z. and J.K.B. wrote the manuscript. The authors declare no competing financial interest.Attached Files
Published - acscentsci.8b00008.pdf
Supplemental Material - oc8b00008_si_001.pdf
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Additional details
- PMCID
- PMC5879481
- Eprint ID
- 85243
- Resolver ID
- CaltechAUTHORS:20180312-100907248
- GM061077
- NIH
- GM074813
- NIH
- Croucher Foundation
- DGE-1144469
- NSF Graduate Research Fellowship
- Created
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2018-03-12Created from EPrint's datestamp field
- Updated
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2022-03-15Created from EPrint's last_modified field