5C8E

Crystal structure of Thermus thermophilus CarH bound to adenosylcobalamin and a 26-bp DNA segment

Summary for 5C8E

• Entry DOI: 10.2210/pdb5c8e/pdb
• Related: 5C8A 5C8D 5C8F
• Descriptor: Light-dependent transcriptional regulator CarH, 26-mer DNA segment containing the CarH operator sequence (antisense strand), 26-mer DNA segment containing the CarH operator sequence (sense strand), ... (5 entities in total)
• Functional Keywords: transcription factor, light sensor, adenosylcobalamin-binding, dna-binding, transcription regulator-dna complex, transcription regulator/dna
• Biological source: Thermus thermophilus (strain HB27 / ATCC BAA-163 / DSM 7039); More
• Total number of polymer chains: 12
• Total formula weight: 311179.54

Authors

Jost, M.,Drennan, C.L. (deposition date: 2015-06-25, release date: 2015-09-30, Last modification date: 2023-09-27)

Primary citation

Jost, M.,Fernandez-Zapata, J.,Polanco, M.C.,Ortiz-Guerrero, J.M.,Chen, P.Y.,Kang, G.,Padmanabhan, S.,Elias-Arnanz, M.,Drennan, C.L.
Structural basis for gene regulation by a B12-dependent photoreceptor.
Nature, 526:536-541, 2015

PubMed Abstract: Photoreceptor proteins enable organisms to sense and respond to light. The newly discovered CarH-type photoreceptors use a vitamin B12 derivative, adenosylcobalamin, as the light-sensing chromophore to mediate light-dependent gene regulation. Here we present crystal structures of Thermus thermophilus CarH in all three relevant states: in the dark, both free and bound to operator DNA, and after light exposure. These structures provide visualizations of how adenosylcobalamin mediates CarH tetramer formation in the dark, how this tetramer binds to the promoter -35 element to repress transcription, and how light exposure leads to a large-scale conformational change that activates transcription. In addition to the remarkable functional repurposing of adenosylcobalamin from an enzyme cofactor to a light sensor, we find that nature also repurposed two independent protein modules in assembling CarH. These results expand the biological role of vitamin B12 and provide fundamental insight into a new mode of light-dependent gene regulation.

PubMed: 26416754
DOI: 10.1038/nature14950

Experimental method

X-RAY DIFFRACTION (3.89 Å)