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Cas9 (CRISPR associated protein 9, formerly called Cas5, Csn1, or Csx12) is a 160 kilodalton protein which plays a vital role in the immunological defense of certain bacteria against DNA viruses and plasmids, and is heavily utilized in genetic engineering applications.
Cas9 (or "CRISPR-associated protein 9") is an enzyme that uses CRISPR sequences as a guide to recognize and open up specific strands of DNA that are complementary to the CRISPR sequence. Cas9 enzymes together with CRISPR sequences form the basis of a technology known as CRISPR-Cas9 that can be used to edit genes within living organisms.
The CRISPR/Cas9 system is also designed as a gene editing technology for the treatment of HIV-1/AIDS. CRISPR/Cas9 has been developed as the latest gene editing technique that allows the insertion, deletion and modification of DNA sequences and provides advantages in the disruption of the latent HIV-1 virus.
CRISPR-Cas9 genome editing techniques have many potential applications. The use of the CRISPR-Cas9-gRNA complex for genome editing [10] was the AAAS's choice for Breakthrough of the Year in 2015. [11] Many bioethical concerns have been raised about the prospect of using CRISPR for germline editing, especially in human embryos. [12]
See: Guide RNA, CRISPR. Complementary base pairing between the sgRNA and genomic DNA allows targeting of Cas9 or dCas9. A small guide RNA (sgRNA), or gRNA is an RNA with around 20 nucleotides used to direct Cas9 or dCas9 to their targets. gRNAs contain two major regions of importance for CRISPR systems: the scaffold and spacer regions.
The CRISPR-Cas9 system consists of an enzyme called Cas9 and a special piece of guide RNA (gRNA). Cas9 acts as a pair of ‘molecular scissors’ that can cut the DNA at a specific location in the genome so that genes can be added or removed. The guide RNA has complementary bases to those at the target location, so it binds only there.
Fast-paced developments in the CRISPR-Cas9 gene editing technology has increased both the concerns and relevance of this ethical controversy as it has become more popularly used. [19] [20] The scientific community recommends continued evaluation of risks and benefits of utilizing genetically modified organisms in everyday life. [21]
Designer nuclease systems such as CRISPR-cas9 are becoming increasingly popular research tools as a result of their simplicity, scalability and affordability. [10] [11] With this being said, off-target genetic modifications are frequent and can alter the function of otherwise intact genes. Multiple studies using early CRISPR-cas9 agents found ...