Cas9 protein

The story starts since CRISPR–Cas9 discovery. Noticed and appreciated  by Emmanuelle Charpentier. After spending years working on Streptococcus pneumoniae bacteria defense mechanisms against antibiotics. She discovered an RNA that controls the synthesis of a class of molecules that are important in pro-life and self-defense processes. The though she spotted on was a patterned stretch of DNA called CRISPR in the genome of some bacteria, where it serves as part of a defense system against viruses. By copying part of an invading virus’ DNA and inserting it into that stretch, bacteria are able to recognize the virus if it invades again, and attack it by cutting its DNA. Different CRISPR systems have different ways of organizing that attack; all of the systems known at the time involved an RNA molecule called CRISPR RNA. Using bioinformatics in collaboration with Jörg Vogel they’ve noticed a dependency between used programmed sequence RNA and result on the genome. That showed up 3 main elements of this method tracrRNA, CRISPR RNA and the Cas9 protein which was noticed in 2005 by lexander Bolotin, French National Institute for Agricultural Research (INRA). But the first scientist that totticed CRISPR was . Also the coded part of the RNA (crRNA) was traced by John van der Oost from Netherlands this time using E-scherichia coli bacteria. The next breakthrough was made in 2008 by Marraffini and Sontheimer from USA. They evidenced that using CRISPR technique  works not as RNA suppressor but in fact targets DNA. The next discovery belonged again to Emmanuelle Charpentier. She noticed tracrRNA forms a duplex with crRNA, and that it is this duplex that guides Cas9 to its targets.  In thge summer of 2009 together with Elitza Deltcheva made and successful experiment of editing DNA. Another step was achieved in 2011 by Virginijus Siksnys from Lithuania. The team “transplanted” CRISPR into the bacteria which does not contain a Type II system – E. coli. The experiment wass succesful – the CRISPR unit turned out to be autonomous. They also successfully made experiments with programmed crRNA part. But the real use was done by Feng Zhang from Broad Institute of MIT that have demonstrated targeted genome erase in human and mouse cells.