Chemistry Nobel for ‘genetic scissors’
Frenchwoman Emmanuelle Charpentier and American Jennifer A Doudna have been awarded the 2020 Nobel Prize in Chemistry for developing ‘one of gene technology’s sharpest tools’, the Royal Swedish Academy of Sciences said October 7, 2020.
- The CRISPR / Cas9 genetic scissors developed by Charpentier and Doudna can be used to change the deoxyribonucleic acid (DNA) of animals, plants and microorganisms with extremely high precision, the Academy’s statement said.
- This technology has had a revolutionary impact on the life sciences. It was contributing to new cancer therapies. It might make the dream of curing inherited diseases come true, the statement added.
- The discovery of the ‘genetic scissors’ was serendipitous. Charpentier, while studying the Streptococcus pyogenes, a bacterium that causes the most harm to humanity, discovered a previously unknown molecule, tracrRNA.
- Her work showed that tracrRNA was part of bacteria’s ancient immune system, CRISPR/Cas, that disarmed viruses by cleaving their DNA.
- Charpentier published her discovery in 2011. The same year, she initiated a collaboration with Jennifer Doudna, an experienced biochemist with vast knowledge of ribonucleic acid.
- Together, they succeeded in recreating the bacteria’s genetic scissors in a test tube and simplifying the scissors’ molecular components so they were easier to use.
- The duo then reprogrammed the genetic scissors. In their natural form, the scissors recognise DNA from viruses, but Charpentier and Doudna proved that they could be controlled so that they can cut any DNA molecule at a predetermined site. Where the DNA is cut, it is then easy to rewrite the code of life.
- The use of CRISPR / Cas9 genetic scissors has exploded since its discovery in 2012. It has contributed to many important discoveries in basic research.
About CRISPR CAS-9
- CRISPR is a dynamic, versatile tool that allows us to target nearly any genomic location and potentially repair broken genes. It can remove, add or alter specific DNA sequences in the genome of higher organisms.
- CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) are sections of DNA and are sections of genetic code containing short repetitions of base sequences followed by spacer DNA segments.
- CAS-9 (CRISPR-associated protein 9) is an enzyme. It uses a synthetic guide RNA to introduce a double strand break at a specific location within a strand of DNA. It is a system used by bacterial cells to recognize and destroy viral DNA as a form of adaptive immunity.
- CRISPR scans the genome looking for the right location and then uses the Cas9 protein as molecular scissors to snip through the DNA.
- Cas9 endonuclease – guide RNAs to direct it to a particular sequence to be edited. The genetic sequence of the RNA matches the target sequence of the DNA that has to be edited.
- When Cas9 cuts the target sequence, the cell repairs the damage by replacing the original sequence with an altered version.
- Unlike other gene-editing methods, it is cheap, quick, easy, safer and more accurate to use because it relies on RNA–DNA base pairing, rather than the engineering of proteins that bind particular DNA sequences.