This year’s Nobel in Chemistry for a magical genetic tool: the CRISPR/Cas9 ‘scissors’

THE citation for the year’s Nobel Prize in Chemistry sounds rather trite, merely saying that the prize was awarded jointly to Emmanuelle Charpentier and Jennifer A. Doudna “for the development of a method for genome editing”. Emmanuelle Charpentier and Jennifer Doudna, they said, had discovered one of gene technology’s sharpest tools—the CRISPR/Cas9 “genetic scissors”—which researchers can use to change the DNA of animals, plants and microorganisms with extremely high precision. In June 2012, Emmanuelle Charpentier and Jennifer Doudna published the ground-breaking paper that showed how this natural immunity machinery of lesser species could be converted into a “programmable” and easy-to-use editing tool to cleave the DNA of any organism at any predetermined site. It has been said about Emmanuelle Charpentier that she always looks for the unexpected; quoting Louis Pasteur, she herself has said: “Chance favours the prepared mind.” The story of the work that led to the discovery of CRISPR/Cas9 goes back to 1987 when the Japanese researcher Yoshizumi Ishino noted the presence of unusual sequences repeated in the genome of the organism Escherichia coli that were interspersed by different spacer sequences. The CRISPR/Cas system that Jennifer Doudna’s group had been working with belonged to Class 1, whereas the system that Emmanuelle Charpentier was working with in S. pyogenes belonged to the simpler Class 2.