UPDATED CAS9 AS A VERSATILE TOOL FOR ENGINEERING BIOLOGY

by the Team

MONACO. The CRISPR-Cas9 system is based off a natural system used by bacteria to protect themselves against viruses. The technology is causing a stir as it is now being used in human cells, where changing just a single base pair makes a huge difference with diseases such as sickle cell anemia.

The technology consists of a synthetic guide RNA and Cas9 protein. Cas9 is an endonuclease enzyme and it can cut DNA. The guide RNA is made to match the target. The RNA guides the enzyme to the target DNA. Cas9 uses two tiny “molecular scissors” to edit specific DNA (and more recently RNA as well).

CRISPR-Cas 9 mechanism

Bacteria are most abundant in nature, so must be having something to face the challenges by their enemies like bacteriophages.

The game plan is “learn about the enemy”

So when bacteria gets infected by a virus that’s a bacteriophage. To resist infection, what bacteria do is “acquisition of bacteriophage sequences into CRISPR loci which mediates sequence specific adaptive immune response in bacteria.

CRISPR genes produces RNA molecules with matching sequence.

They grab on the virus’s RNA and prevent them from being turned into proteins.

Halt in virus factory!!

and bacteria hold onto an invading virus’s DNA and build libraries which when microbe reproduces are passed down to its decendents including the ones acquired in its own lifetime.

How ?

CRISPR has short palindromic repeats separated by short nonrepetitive sequences called “spacers”, whose one of the sources can be a phage.

Which is copied and incorporated into CRISPR locus that includes the set of genes that encode CRISPR associated endonucleases (Cas) which introduce cuts in the genome.

In case of same infection.

RNA molecules + Cas complex + transactivating CrRNA (tracrRNA) (which will guide endonuclease to exogenous sequence)

This Cas RNA complex will recognise the DNA target that is complementary to CrRNA (guide) and adjacent to specific proto spacer.

Complex cuts and deactivates the invading DNA.

So this is what bacteria do for survival. But how can this technique be benificial for engineering higher organisms.

So by this you can get gene editing mechanism by which you can introduce do precise gene corrections or insertions.

CRISPR will change how we humans live.

1. We would have the “perfect” people
2. CRISPR has the potential to eradicate diseases, so half the doctors may lose their jobs
3. The world would be very competitive
4. This technology will unintentionally reproduce social injustice and discrimination
5. CRISPR can increase an individual’s lifespan
6. Organ farming would be made possible (this is possible with pig and human organs).

CRISPR is a powerful tool. There are high chances that this technology may fall into the wrong hands. Once the people use it for their own benefit, the world would be chaotic. Just imagine, taking out what you don’t like and replacing them with something better. That’s what it is like. Furthermore, abnormalities could be treated because of designer babies, a “perfect” baby.

Of course, the future is still unknown. But these are some possibilities in a decade or two. Its an amazing technology with its pros and cons.