The Transcription Factor CarH Safeguards Use of Adenosylcobalamin as a Light Sensor by Altering the Photolysis Products
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Author(s)
Jost, Marco
Simpson, Jeffrey H.
Drennan, Catherine L.
Date Issued
May 2015
Journal
Biochemistry
Publisher
American Chemical Society (ACS)
Citation
Jost, Marco, Jeffrey H. Simpson, and Catherine L. Drennan. “The Transcription Factor CarH Safeguards Use of Adenosylcobalamin as a Light Sensor by Altering the Photolysis Products.” Biochemistry 54.21 (2015): 3231–3234. © 2015 American Chemical Society
Version
Final published version
Abstract
The newly discovered light-dependent transcription factor CarH uses adenosylcobalamin as a light sensor to regulate expression of protective genes in bacteria upon exposure to sunlight. This use of adenosylcobalamin is a clever adaptation of a classic enzyme cofactor, taking advantage of its photolabile Co−C bond. However, it is also puzzling in that photolysis of
adenosylcobalamin generates the 5′-deoxyadenosyl radical that could damage DNA. Here, using liquid chromatography and spectroscopic techniques, we demonstrate that CarH suppresses release of the 5′-deoxyadenosyl radical and instead effects conversion to a nonreactive 4′,5′-anhydroadenosine. In this manner, CarH safeguards use of
adenosylcobalamin in light-dependent gene regulation.
MIT Department
Massachusetts Institute of Technology. Department of Biology
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/acs.biochem.5b00416
