CRISPR

“Imagine having the power to edit the DNA of living organisms—Welcome to the world of CRISPR, where science fiction is becoming science fact!”

What's more astounding is the way it was discovered! The discovery of these clustered DNA sequences occurred independently in three different parts of the world. The first discovery was in 1987 by Yoshizumi, a researcher at Osaka University. It was serendipity—they accidentally cloned part of a CRISPR sequence together with the "iap" gene of *Escherichia coli* (a bacterium). The second discovery occurred in 1993. Two researchers studying *Mycobacterium tuberculosis* in the Netherlands observed diversity in its DNA sequences. The third discovery was by Francisco Mojica at the University of Alicante in Spain. He studied the function of repeats in the archaeal species *Haloferax* and *Haloarcula*. Transcription of these interrupted repeats led to the first full characterization of CRISPR.

Do you know that Cas9 (or also known as "CRISPR-associated protein 9") is an enzyme that opens up specific strands of DNA that are complementary to the CRISPR sequence. For this, it uses the CRISPER sequence as a guide.

Cas9 and CRISPR sequences is the basis of a CRISPR-Cas9 that is used to edit genes within living organisms. The applications include biological research, development of biotechnological products and treatment of diseases.
The CRISPR-Cas9 system consists of two key molecules that cause mutations into the DNA. These are:

• An enzyme called Cas9, also known as a pair of 'molecular scissors' that can cut the two strands of DNA at a specific location.
• A piece of RNA called guide RNA (gRNA) which consists of a small piece of pre-designed RNA sequence (about 20 bases long) within a longer RNA scaffold. This sequence guides the Cas 9 to right part for the scaffold to bind to the DNA.
• The Cas9 follows the guide RNA to the same location in the DNA sequence and makes a double stranded cut across both strands of the DNA.
• At this stage the cell recognizes that the DNA is damaged and tries to repair it.

Therefore, the CRISPER Cas9 system works on the principle of homologous recombination, where two homologous chromosomes combine. The target sequence (complementary to the sgRNA sequence) is followed by two cytosine nucleotides because the sgRNA binds best when the opposite DNA strand is comprised of any nucleotide followed by two guanines (-NGG). This sequence is called a Protospacer Adjacent Motif (PAM) sequence.

In Conclusion, the development of this new tool was only possible due to the pioneering work of researching about the 2D structural and functional properties of Leptospira genomics.

The birth of "molecular scissors" Cas9 and the system of guide RNA would soon enable biologists to make extremely precise alterations in the DNA strand of an organism. The introduction of genetic transformation and planting changed everything for humanity, agriculture, and medicine as areas previously defined by boundaries of science fiction were newly opened. Simulations of Cas9 have undoubtedly changed the notions tethering the future of genetic and therapeutic engineering.

Summary

CRISPER is no doubt one of the most successful inventions for gene editing, which is itself a heroic cure for many uncurable diseases. What's more interesting is its discovery and its working!

The invention of CRISPR, which now encompasses clustered DNA sequences, was nothing short of revolutionary for genetic studies in the world. The amazing finding of CRISPR-Cas9 stemmed from researchers working independently in Spain, Japan, and the Netherlands in the late 1980s and early 1990s.

The invention of CRISPR, which now encompasses clustered DNA sequences, was nothing short of revolutionary for genetic studies in the world. The amazing finding of CRISPR-Cas9 stemmed from researchers working independently in Spain, Japan, and the Netherlands in the late 1980s and early 1990s.

References

• CRISPR-Wikipedia
• Methods and Technology
• CRISPR/Cas9 gene editing

Free Resources

• rhAmpSeq™ CRISPR Data Analysis Tool
• Genome Engineering
• Introduction to CRISPR-Cas9 Techniques