Two distinct DNA binding modes guide dual roles of a CRISPR-cas protein complex

Timothy R. Blosser, Luuk Loeff, Edze R. Westra, Marnix Vlot, Tim Künne, Małgorzata Sobota, Cees Dekker, Stan J.J. Brouns, Chirlmin Joo

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

Small RNA-guided protein complexes play an essential role in CRISPR-mediated immunity in prokaryotes. While these complexes initiate interference byflagging cognate invader DNA for destruction, recent evidence has implicated their involvement innew CRISPR memory formation, called priming, against mutated invader sequences. The mechanism by which the target recognition complex mediates these disparate responses-interference and priming-remains poorly understood. Using single-molecule FRET, we visualize how bona fide and mutated targets are differentially probed by E.coli Cascade. We observe that the recognition of bona fide targets is an ordered process that is tightly controlled forhigh fidelity. Mutated targets are recognized with low fidelity, which is featured by short-lived and PAM- and seed-independent binding by any segment of the crRNA. These dual roles of Cascade in immunity with distinct fidelities underpin CRISPR-Cas robustness, allowing for efficient degradation ofbona fide targets and priming of mutated DNA targets.

Original languageEnglish
Pages (from-to)60-70
Number of pages11
JournalMolecular Cell
Volume58
Issue number1
DOIs
StatePublished - 2 Apr 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier Inc.

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