Structural basis for gene regulation by a B12-dependent photoreceptor.
Nature
; 526(7574): 536-41, 2015 Oct 22.
Article
em En
| MEDLINE
| ID: mdl-26416754
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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Vitamina B 12
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Regulação Bacteriana da Expressão Gênica
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Thermus thermophilus
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Cobamidas
Idioma:
En
Revista:
Nature
Ano de publicação:
2015
Tipo de documento:
Article