Cas13b orthologues CRISPR enzymes and systems
The invention provides for systems, methods, and compositions for targeting nucleic acids. In particular, the invention provides non-naturally occurring or engineered RNA-targeting systems comprising a novel RNA-targeting Cas13b effector protein and at least one targeting nucleic acid component like a guide RNA or crRNA.
1. An engineered composition comprising:
i) a Cas13b effector protein comprising the amino acid sequence of SEQ ID NO:32, and
ii) an engineered guide RNA,
wherein the engineered guide RNA is capable of forming a CRISPR-Cas complex with the Cas13b effector protein and comprises a) a guide sequence that directs sequence specific binding to a target RNA sequence other than a naturally occurring Prevotella intermedia Cas13b protospacer and that reprograms the CRISPR-Cas complex to bind said target RNA sequence, and b) a direct repeat sequence.
2. The engineered composition of claim 1 , which comprises an accessory protein that enhances the activity of the Cas13b effector protein or represses activity of the Cas13b effector protein.
3. The engineered composition of claim 2 , wherein the accessory protein that enhances the activity of the Cas13b effector protein is a csx28 protein.
4. The engineered composition of claim 2 , wherein the accessory protein that represses the activity of the Cas13b effector protein is a csx27 protein.
5. The engineered composition of claim 1 , which comprises two or more engineered guide RNAs.
6. The engineered composition of claim 1 , wherein the engineered guide RNA hybridizes to a target RNA sequence in a prokaryotic cell.
7. The engineered composition of claim 1 , wherein the engineered guide RNA hybridizes to a target RNA sequence in a eukaryotic cell.
8. The engineered composition of claim 1 , wherein the Cas13b effector protein comprises one or more nuclear localization signals (NLSs).
9. The engineered composition of claim 2 , wherein the Cas13b effector protein and the accessory protein are from the same organism.
10. The engineered composition of claim 2 , wherein the Cas13b effector protein and the accessory protein are from different organisms.