Conformational Control of Cascade Interference and Priming Activities in CRISPR Immunity.
Mol Cell
; 64(4): 826-834, 2016 11 17.
Article
em En
| MEDLINE
| ID: mdl-27871367
ABSTRACT
During type I-E CRISPR-Cas immunity, the Cascade surveillance complex utilizes CRISPR-derived RNAs to target complementary invasive DNA for destruction. When invader mutation blocks this interference activity, Cascade instead triggers rapid primed adaptation against the invader. The molecular basis for this dual Cascade activity is poorly understood. Here we show that the conformation of the Cse1 subunit controls Cascade activity. Using FRET, we find that Cse1 exists in a dynamic equilibrium between "open" and "closed" conformations, and the extent to which the open conformation is favored directly correlates with the attenuation of interference and relative increase in priming activity upon target mutation. Additionally, the Cse1 L1 motif modulates Cascade activity by stabilizing the closed conformation. L1 mutations promote the open conformation and switch immune response from interference to priming. Our results demonstrate that Cascade conformation controls the functional outcome of target recognition, enabling tunable CRISPR immune response to combat invader evolution.
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MEDLINE
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Plasmídeos
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Regulação Bacteriana da Expressão Gênica
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Proteínas de Escherichia coli
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Escherichia coli K12
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Proteínas Associadas a CRISPR
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Sistemas CRISPR-Cas
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article