Cas13b Is a Type VI-B CRISPR-Associated RNA-Guided RNase Differentially Regulated by Accessory Proteins Csx27 and Csx28
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Author(s)
Shmakov, Sergey
Makarova, Kira S.
Koonin, Eugene V.
Smargon, Aaron Andrew
Cox, David Benjamin Turitz
Pyzocha, Neena
Zheng, Kaijie
Slaymaker, Ian
Gootenberg, Jonathan S
Essletzbichler, Patrick
Date Issued
January 2017
Journal
Molecular Cell
Publisher
Elsevier
Citation
Smargon, Aaron A. et al. “Cas13b Is a Type VI-B CRISPR-Associated RNA-Guided RNase Differentially Regulated by Accessory Proteins Csx27 and Csx28.” Molecular Cell 65, 4 (February 2017): 618–630 © 2017 Elsevier
Version
Author's final manuscript
Abstract
CRISPR-Cas adaptive immune systems defend microbes against foreign nucleic acids via RNA-guided endonucleases. Using a computational sequence database mining approach, we identify two class 2 CRISPR-Cas systems (subtype VI-B) that lack Cas1 and Cas2 and encompass a single large effector protein, Cas13b, along with one of two previously uncharacterized associated proteins, Csx27 and Csx28. We establish that these CRISPR-Cas systems can achieve RNA interference when heterologously expressed. Through a combination of biochemical and genetic experiments, we show that Cas13b processes its own CRISPR array with short and long direct repeats, cleaves target RNA, and exhibits collateral RNase activity. Using an E. coli essential gene screen, we demonstrate that Cas13b has a double-sided protospacer-flanking sequence and elucidate RNA secondary structure requirements for targeting. We also find that Csx27 represses, whereas Csx28 enhances, Cas13b-mediated RNA interference. Characterization of these CRISPR systems creates opportunities to develop tools to manipulate and monitor cellular transcripts.
MIT Department
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Department of Biology
Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
McGovern Institute for Brain Research at MIT
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Creative Commons Attribution-NonCommercial-NoDerivs License
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DOI of Published Version
https://doi.org/10.1016/J.MOLCEL.2016.12.023
