CRISPRCas12a

CRISPR-Cas12a, also known as Cpf1, is a gene-editing system derived from the CRISPR-Cas immune system of bacteria. Unlike the more widely known CRISPR-Cas9 system, Cas12a possesses distinct characteristics that make it a valuable tool in molecular biology. It is a single effector protein that can be guided by a CRISPR RNA (crRNA) to a target DNA sequence.

A key difference between Cas12a and Cas9 is its PAM (protospacer adjacent motif) recognition sequence. Cas12a typically recognizes a T-rich PAM (e.g., TTTV, where V can be A, C, or G) located upstream of the target sequence. This contrasts with Cas9, which usually recognizes a G-rich PAM. This difference in PAM specificity allows for targeting of different genomic regions.

Another notable feature of Cas12a is its mechanism of DNA cleavage. It creates staggered cuts in the double-stranded DNA, leaving short overhangs, whereas Cas9 typically produces blunt ends. Furthermore, upon binding to its target DNA, Cas12a exhibits a "collateral cleavage" activity, meaning it can non-specifically cleave other single-stranded DNA molecules in the vicinity. This property has been exploited for various diagnostic applications.

Cas12a systems have been engineered for enhanced specificity and efficiency. They are employed in a range of genome editing applications, including gene knockout, gene insertion, and the detection of nucleic acids. Its ability to recognize different PAM sequences and its staggered cutting mechanism offer complementary capabilities to the CRISPR-Cas9 system, broadening the scope of CRISPR-based technologies.