The Transcription Factor CarH Safeguards Use of Adenosylcobalamin as a Light Sensor by Altering the Photolysis Products
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 photola...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Chemical Society (ACS)
2017
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| Online Access: | http://hdl.handle.net/1721.1/110584 https://orcid.org/0000-0001-5486-2755 |
| Summary: | 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. |
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