A Conversation with Jennifer Doudna, Interviewer: Jan Witkowski, Executive Director, Banbury Center at Cold Spring Harbor Laboratory
Reporter: Aviva Lev-Ari, PhD, RN
A Conversation with Jennifer Doudna
INTERVIEWER: JAN WITKOWSKI Executive Director, Banbury Center at Cold Spring Harbor Laboratory
Jennifer Doudna is a Professor in the Department of Chemistry and the Department of Molecular and Cell Biology at the University of California –Berkeley.
Jan Witkowski: People know of you primarily through your work on the CRISPR –Cas9 system for genetic engineering. Can you go over the biology of the system and how you got involved in working on it?
Dr. Doudna: We started working on CRISPR (clustered regularly interspaced short palindromic repeats) biology about 10 years ago. A colleague of mine at Berkeley, Jillian Banfield, was doing research on bacterial comJmunities and the viruses that infect them. She had noticed a lot of repetitive sequences in their genomic data and wondered if these were being used in the form of RNA molecules to protect the bacteria from viral infection. This led to our work with Emmanuelle Charpentier to understand the function of a particular protein called Cas9 (CRISPRassociated protein 9), which turns out to be an RNAguided DNA cutting enzyme. This is a great way for bacteria to fight viruses. It’s an adaptive immune system. The bacteria acquire genetic material from viruses and insert them into these CRISPR sequences. They can transcribe the stored sequence into RNA, and then those RNA molecules can base-pair the matching viral DNAs sequences. They use RNA molecules to target the viral sequences and Cas9 cuts the viral DNA. About half of the sequenced bacterial genomes have one or more CRISPR loci in the genome. Jan
Witkowski: Why is it not more widespread?
Dr. Doudna: Bacteria have a lot of ways to avoid viruses. CRISPR systems operate in certain kinds of bacteria, perhaps in certain environments where they’re particularly advantageous. Other bacteria simply might not need them because they have other ways of fighting the viruses they encounter.
Jan Witkowski: Bacteria have different enzymes depending on the type of CRISPR system, but Cas9 is the one that caught people’s attention for genome engineering. Why is that particularly useful?
Dr. Doudna: It’s programmable. It can be targeting using a short sequence of RNA that provides the base-pairing information to recognize DNA molecules with a matching or complementary sequence. Cas9 is also useful because the enzyme cuts both strands of double-stranded DNA.
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