CRISPR Office Hours with Jennifer Doudna

Dr. Jennifer Doudna is a researcher that needs no introduction in the field of genetics. In 2012, she co-discovered that CRISPR Cas9 enzymes could be used for genome editing-- a monumental finding that revolutionized the field of gene editing. Dr. Doudna is a Professor in the Department of Chemistry and the Department of Molecular and Cell Biology at the University of California, Berkeley, and investigator at the Howard Hughes Medical Institute. She is also the President and Chair of the Innovative Genomics Institute (IGI) Governance Board.

Doudna briefly explained how CRISPR technology works. In the 2012 paper that she published in collaboration with Emmanuelle Charpentier and her lab members, the researchers reported how Cas9 worked with the crRNA and tracrRNA to interact with DNA in a programmable fashion at a 20 letter sequence that matches the CRISPR sequence resulting in a double-stranded break induced by the Cas9 protein. Subsequently, this led to the transformational discovery that the system could be re-engineered as a single guided system by linking together the crRNA and the tracr RNA as a single-guide RNA (sgRNA). This sgRNA provided the target information on one end and the structural handle for binding to Cas9 on the other.

Dr. Doudna also spoke about some of the potential applications of CRISPR. She gave the example of sickle cell anemia where CRISPR editing has been used for the treatment by correcting the disease-causing mutation. Recently, CRISPR Therapeutics, a company started by Emmanuelle Charpentier reported that a patient,

Recently, in collaboration with Dr. Jill Banfield’s lab at UC Berkeley, Dr. Doudna’s team found that they are big phages that infect bacteria in the environment and those big phages carry around their own CRISPR systems. They discovered that these phages use a compact CasΦ protein to trick bacteria into fighting off rival viruses instead of itself. CasΦ is one of the smallest Cas proteins known to date; the small size of this protein makes it a lot easier to deliver it into cells as compared to Cas9 and could help solve many problems associated with the latter.

Dr. Doudna also discussed her involvement in the development of novel CRISPR-based COVID-19 diagnostic, and how she spearheaded the transformation of the IGI into a high-throughput COVID-19 testing facility.

Their diagnostic test uses the Cas13 protein which targets the RNA instead of the DNA. For Cas13, when the RNA guided protein interacts with an RNA target sequence, the protein turns on its RNA cutting activity. However, it is not restricted to the sequence of RNA that it is bound to and is able to cut other RNA molecules in its vicinity. So, when these RNA molecules are hooked onto fluorophores, a signal can be detected when this RNA gets cut. Cas12, which targets DNA also had similar abilities and could be used for diagnostics as well. For more information on CRISPR diagnostics for COVID-19, check out this blog.

As you might already know, our CRISPR Office hours episode is not complete without questions from the audience. This week, we had a number of great questions and we have selected a few to discuss below.

Interested in learning more about Jennifer Doudna and her work? We have put together a list of resources for you to check out.

With that, we have now come to the end of CRISPR Office Hours. We hope you have enjoyed attending our sessions and found them useful. For recaps of any of the past episodes, check out our recap blog posts and Youtube channel.