Sparks of the CRISPR explosion: Applications in medicine and agriculture

Exactly 30 years ago, Nakata and coworkers published a paper analyzing the 1664-nucleotide sequence of a chromosomal DNA segment that contained the iap gene and its flanking regions in Escherichia coli. At the end of their paper, the authors reported that “an unusual structure was found in the 30-end flanking region of iap”. “Five highly homologous sequences of 29 nucleotides were arranged as direct repeats with 32 nucleotides as spacing”. In the following decade, similar structures have been found in many other prokaryotes. In 2002, these structures have been called clustered regularly interspaced short palindromic repeats (CRISPR). The CRISPR and CRISPR-associated (Cas) endonuclease act as a defense system against invading viruses and plasmids in many different bacterial species. In 2012, Doudna, Charpentier and colleagues applied the CRISPR/Cas system in gene targeting by bringing RNA, protein and DNA into the same locus. This milestone work triggered the “CRISPR explosion” for genome engineering