CRISPR-associated endonuclease Cas9 (Streptococcus pyogenes) (SpCas9) (SpCas9)

CRISPR-associated endonuclease Cas9 from Streptococcus pyogenes (SpCas9) is a 160 kDa RNA-guided DNA endonuclease that serves as the effector protein in Type II CRISPR-Cas systems [UniProt: Q99ZW2]. It functions by forming a complex with a guide RNA (gRNA) that directs the enzyme to a specific 20-nucleotide DNA sequence adjacent to a 5'-NGG-3' protospacer adjacent motif (PAM) [PubMed: 22745249]. Upon target recognition, SpCas9 utilizes its HNH and RuvC-like nuclease domains to generate a double-strand break (DSB) in the DNA. This break triggers cellular DNA repair pathways, such as non-homologous end joining (NHEJ) or homology-directed repair (HDR), which can be harnessed to knock out genes or introduce precise genetic corrections [PubMed: 23328324]. SpCas9 is the primary component of the first FDA-approved CRISPR-based therapy, exagamglogene autotemcel, which treats sickle cell disease and beta-thalassemia by editing the BCL11A enhancer in hematopoietic stem cells [FDA: Casgevy]. Clinical development is also underway for in vivo applications targeting the liver, eye, and infectious agents like HIV [ClinicalTrials.gov: NCT04601051]. Key therapeutic considerations include the risk of off-target mutations and the potential for pre-existing immune responses in patients previously exposed to Streptococcus pyogenes [PubMed: 29300637].

Other names

Cas9Csn1CRISPR-associated protein 9Streptococcus pyogenes Cas9

RNA-guided double-strand DNA cleavage followed by non-homologous end joining (NHEJ) or homology-directed repair (HDR).