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CRISPR/Cpf1 is a DNA-editing technology. It works analogously to CRISPR/Cas9 which has revolutionized research in genome editing. Like its predecessor, it is derived from a mechanism that bacteria use to acquire immunity from viruses. CRISPR/Cpf1 is potentially better than CRISPR/Cas9 as Cpf1 is a smaller and simpler endonuclease (a type of enzyme) than Cas9. That simplifies delivery to the cells whose genes need modifying.[1]
Mechanism of action
Endonuclease-based systems such as CRISPR/Cpf1 consist of a pair of enzymatic “scissors” (the Cpf1) and a guide sequence made of DNA (the CRISPR) that positions the scissors at the correct spot on the double helix. Since cells must protect themselves against a host of viruses (to remove viral DNA), it has been hypothesized that each such virus has a complementary endonuclease, offering the possibility that many more types of scissors remain to be discovered.[1]
Cas9 requires two RNA molecules to cut DNA while Cpf1 needs one. The proteins also cut DNA at different places, offering researchers more options when selecting an editing site. Cas9 cuts both strands in a DNA molecule at the same position, leaving behind ‘blunt’ ends. Cpf1 leaves one strand longer than the other, creating 'sticky' ends that are easier to work with. Cpf1 appears to be more able to insert new sequences at the cut site, compared to Cas9.[2]
Cpf1 is a single RNA-guided endonuclease that lacks tracrRNA. It utilizes a T-rich protospacer-adjacent motif. Cpf1 cleaves DNA via a staggered DNA double-stranded break.
Discovery
CRISPR/Cpf1 was found by searching a published database of bacterial genetic sequences for promising bits of DNA. Cpf1 appeared in many species;[1] the ultimate Cpf1 endonuclease that was developed into a tool for genome editing was taken from one of 16 bacteria that harbored it.[2]
Two candidate enzymes from Acidaminococcus and Lachnospiraceae bacterium display efficient genome-editing activity in human cells.[3]
See also
References
- ^ a b c "Even CRISPR". The Economist. October 3, 2015. ISSN 0013-0613. Retrieved 2015-10-24.
- ^ a b Ledford, Heidi. "Alternative CRISPR system could improve genome editing". Nature. 526 (7571): 17–17. doi:10.1038/nature.2015.18432.
- ^ Zetsche, Bernd; Gootenberg, Jonathan S.; Abudayyeh, Omar O.; Slaymaker, Ian M.; Makarova, Kira S.; Essletzbichler, Patrick; Volz, Sara E.; Joung, Julia; van der Oost, John; Regev, Aviv; Koonin, Eugene V.; Zhang, Feng (October 2015). "Cpf1 Is a Single RNA-Guided Endonuclease of a Class 2 CRISPR-Cas System". Cell. 163 (3): 759–771. doi:10.1016/j.cell.2015.09.038.