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

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

77 Citations (Scopus)


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
JournalMolecular Cell
Issue number1
Publication statusPublished - 2015

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