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Updated: Jan 29, 2026

Genome Engineering of Primary Human B Cells Using CRISPR/Cas9
Published on: November 3, 2020
Engineer chimeric Cas9 to expand PAM recognition based on evolutionary information
Dacheng Ma1, Zhimeng Xu1, Zhaoyu Zhang1
1MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and System Biology, Department of Automation, Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing, 100084, China.
Abstract:
Although Cas9 nucleases are remarkably diverse in microorganisms, the range of genomic sequences targetable by a CRISPR/Cas9 system is restricted by the requirement of a short protospacer adjacent motif (PAM) at the target site. Here, we generate a group of chimeric Cas9 (cCas9) variants by replacing the key region in the PAM interaction (PI) domain of Staphylococcus aureus Cas9 (SaCas9) with the corresponding region in a panel of SaCas9 orthologs. By using a functional assay at target sites with different nucleotide recombinations at PAM position 3-6, we identify several cCas9 variants with expanded recognition capability at NNVRRN, NNVACT, NNVATG, NNVATT, NNVGCT, NNVGTG, and NNVGTT PAM sequences. In summary, we provide a panel of cCas9 variants accessible up to 1/4 of all the possible genomic targets in mammalian cells.
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