Time for an update. Over the summer the Innovative Genomics Initiative (IGI) hosted a one-week CRISPR workshop where various speakers held lectures addressing how they are using the technology in their research and how they propose to proceed with it. IGI made these lectures available here and had, among others, Jennifer Doudna speak about her group’s work on the mechanism of CRISPR/Cas9:
More recently and perhaps a little more excitingly, researchers led by Feng Zhang at the Broad Institute in Cambridge (USA) have published a paper (Zetsche et al., 2015) describing a new protein – called Cpf1 – from the bacterial species Acidaminococcus and Lachnospiraceae that can also cut DNA, like the now widely used Cas9 protein. However, it acts slightly differently from Cas9 in that it only needs a single guide RNA to find its target DNA and importantly, it cuts the DNA in a way that leaves so-called “sticky ends”. These cut sites with “staggered” ends allow much more controlled insertion of new DNA into the cut site. This, in turn, means that cells can now be more easily made to express engineered proteins with specific mutations, for example, or corrected versions of proteins. Although this was possible using the original CRISPR/Cas9 system it was not very efficient. However, pictures supposedly say more than a thousand words so here is their “graphical abstract”…
Lastly, I just want to mention that I have noticed that the original two pioneers of CRISPR technology, Emmanuelle Charpentier and Jennifer Doudna and their research teams, are sticking to basic research. That is to say they study the exact mechanisms by which CRISPR/Cas9 works, elucidate the atomic structures of these protein-RNA-DNA complexes and are still looking for other related systems to better understand how bacteria protect themselves from infections by plasmids (circular bits of DNA) and bacteriophages (viruses that infect bacteria). Despite the high-profile patent case they are involved in and all the other labs around the world that are now using this technology in various applications, such as gene therapy or plant engineering, they remain focussed on simply increasing our knowledge of nature, which I find laudable.
Zetsche B, Gootenberg Jonathan S, Abudayyeh Omar O, Slaymaker Ian M, Makarova Kira S, Essletzbichler P, Volz Sara E, Joung J, van der Oost J, Regev A, Koonin Eugene V, Zhang F (2015) Cpf1 Is a Single RNA-Guided Endonuclease of a Class 2 CRISPR-Cas System. Cell (in press).