CRISPR-Cas12b

CRISPR-Cas12b is a genome editing enzyme and a member of the type V-B CRISPR-Cas system family. It is a dual-RNA-guided endonuclease that functions as a programmable nuclease for targeted DNA editing[3][5]. **Mechanism of action:** Cas12b recognizes and cleaves target DNA sequences guided by crRNA (CRISPR RNA) and tracrRNA components. The enzyme generates double-strand breaks with 6-8 nucleotide 5' sticky ends, which are the longest sticky ends among current CRISPR-Cas systems, promoting non-homologous end joining (NHEJ)-based gene modifications[6]. Cas12b recognizes distal T-rich protospacer adjacent motifs (PAMs), primarily ATTN sequences[5]. **Key advantages:** - Smaller protein size (1,108 amino acids) compared to Cas9 (1,368 amino acids) and Cas12a (1,307 amino acids), making it suitable for viral vector delivery[7] - Higher target specificity and minimal off-target effects compared to Cas9[4][5] - Highly sensitive to mismatches—a single nucleotide mutation in the first 18 nucleotides of the target sequence is sufficient to prevent cleavage[6] - Generates larger deletions (5-15 bp) than other CRISPR systems[5] - Wide temperature and pH stability[4] - Improved stability in human plasma[4]

Other names

Type V-B CRISPR systemBhCas12b (Bacillus hisashii variant)AaCas12b (Alicyclobacillus acidoterrestris variant)