Imagine a ladder with colored rungs and that you want to replace one of the rungs with a rung of a different color. What you do is to get someone who knows how to cut the rung and throw it away. You then make available only rungs of the color you want as replacement. A repairer comes, takes one of the rungs available, and fixes it in the place from where the original rung was cut off. This is a trivial way of imagining how CRISPR-Cas9 works.

The ladder is DNA, which famously has the shape of a double helix. The rungs are nucleotides. A type of bacteria is the one who cuts the rung. The natural repair mechanism of the cell is the repairer. Two researchers Emmanuelle Charpentier and Jennifer Doudna invented this method that has revolutionised the field. They received the 2020 Nobel Prize in chemistry for their work.

Charpentier:

Charpentier was born in Juvisy-sur-Orge in France. She studied biochemistry, microbiology, and genetics at the Pierre and Marie Curie University (now, the Faculty of Science of Sorbonne University) in Paris. She was a graduate student at the Institut Pasteur from 1992 to 1995 and was awarded a research doctorate. Charpentier's PhD project investigated molecular mechanisms involved in antibiotic resistance.

Charpentier had a busy international career. She held positions in Europe at Pierre and Marie Curie University, Institut Pasteur, the Rockefeller University in New York in the US, the New York University Medical Center, laboratory of a skin-cell biologist, St. Jude Children's Research Hospital, and at the Skirball Institute of Biomolecular Medicine in New York.

In 2015 she became a director at the Max Planck Institute for Infection Biology in Berlin. She has been an honorary professor at Humboldt University in Berlin. She is the founding and acting director of the Max Planck Unit for the Science of Pathogens.

Doudna:

Jennifer Doudna was born in Washington, DC, as the daughter of Dorothy Jane and Martin Kirk Doudna. She attended Hilo High School, Hawaii, and graduated from school in 1981. She was an undergraduate student at Pomona College in Claremont, California. She earned her Bachelor of Arts degree in Biochemistry in 1985. She went to Harvard Medical School for her doctoral study and earned a PhD in Biological Chemistry and Molecular Pharmacology in 1989.

After her PhD, Doudna worked at various institutes such as Massachusetts General Hospital, Harvard Medical School, the University of Colorado at Boulder, and Yale University as an assistant professor in the Department of Molecular Biophysics and Biochemistry. While there she started studying CRISPR, exclusively.

Nobel Prize

Charpentier is best known for her Nobel-winning work of deciphering the molecular mechanisms of a bacterial immune system, called CRISPR-Cas9, and repurposing it into a tool for genome editing. In particular, she uncovered a novel mechanism for the maturation of a non-coding RNA which is pivotal in the function of CRISPR-Cas9. Specifically, Charpentier demonstrated that a small RNA called tracrRNA is essential for the maturation of crRNA.

In 2011, Charpentier and Doudna met at a research conference and began a collaboration. They showed that Cas9 (a protein which plays a vital role in the immunological defense of certain bacteria against DNA) could be used to make cuts in any targeted DNA sequence. This discovery demonstrated that the CRISPR-Cas9 technology could be used to edit the genome easily.

Normally, Nobel prizes are awarded to discoveries but there have been exceptions. However, CRIPSR-Cas9 technology has enabled researchers worldwide to employ the method successfully to edit DNA sequences of plants and animals and so on. It has revolutionized genetics by enabling scientists to edit genes and probe their role in health and disease, to develop therapies, and has had a fundamental influence on the field.

Charpentier and Doudna also have several patents to their names.