CRISPR: CAS9's Revolutionary Counterpart

No word encompasses biotechnology quite like this six-letter acronym that every STEM student has probably heard of: CRISPR. Referring to clustered regularly interspaced short palindromic repeats, this term is synonymous with a genetic engineering technique in molecular biology by which the genomes of living organisms may be modified. It’s based on a simplified version of the bacterial CRISPR-Cas 9 antiviral defense system, and possibly the single-handedly most revolutionary biotech achievement of the 21st century.

Since utilizing this technique means successful editing of genomes in vivo, CRISPR is often employed to create new medicines, agricultural products, and GMOs. The development of CRISPR earned Jennifer Doudna and Emmanuelle Charpentier the Nobel Prize in Chemistry around five years ago, in 2020.

Now, CRISPR’s entire biological sequence is based off of Cas9, which works much like genetic scissors. The Cas9 nuclease opens both strands of the targeted sequence of DNA to introduce a modification (this modification to the genome can be specified and chosen by the scientific researchers conducting CRISPR engineering). The modification is completed through knock-in mutations, which allows for the introduction of targeted DNA damage and subsequent repair. The specific biological mechanism that allows for this is homology directed repair (HDR), which uses similar DNA sequences to drive the repair of a break of DNA sequences via the incorporation of exogenous DNA to function as the repair template. 

In eukaryotic cells, genome editing isn’t anything new. In fact, genome editing has been possible since the 1980s, but the various methods that were discovered or built were proven to be largely inefficient and impractical. CRISPR and the Cas9 nuclease molecule are effective, especially at a big scale. Cas9, derived from streptococcus pyogenes, has facilitated targeted genome modification in eukaryotic cells by employing Cas9 insertion and RNA template modification with ease to cause point mutations. Point mutations are targeted, and at specific sites, which contributes to the overall goal of CRISPR: deliberate and specific DNA mutations. 

CRISPR’s versatility and precision are the reasons it is so revolutionary. CRISPR targets specific DNA sequences with unparalleled accuracy, miniziming off-target effects compared to older genome-editing tools like TALENs. Plus, since CRISPR is reproducible, making experiment involving CRISPR affordable and faster. Medicine, agriculture, and epidemiology are just a few of the many fields that could benefit from CRISPR being employed as mainstream technology. CRISPR can reshape how we treat diseases, grow food, and even engineer ecosystems, holding vast potential to revolutionize the world as a whole.