5c8e

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

spinqualitylabelsall models 5c8e, resolution 3.89Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5c8e is a 12 chain structure with sequence from Thermus thermophilus HB27. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.89Å Ligands: 5AD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q746J7_THET2 Publication Abstract from PubMed 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. Structural basis for gene regulation by a B-dependent photoreceptor.,Jost M, Fernandez-Zapata J, Polanco MC, Ortiz-Guerrero JM, Chen PY, Kang G, Padmanabhan S, Elias-Arnanz M, Drennan CL Nature. 2015 Sep 28. doi: 10.1038/nature14950. PMID:26416754 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Transcriptional activator 3D structures

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