Mechanism of DNA Spacer Acquisition during CRISPRCas Adaptive Immunity
Found in many species of bacteria and archaea, the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR associated (Cas) proteins provide an adaptive defense mechanism against foreign invaders such as viruses and plasmids. By integrating segments of the foreign DNA into the CRISPR locus of the host genome, the bacteria remember the invaders and can subsequently produce CRISPR RNAs (crRNAs) to destroy the foreign DNA complementary to the crRNA. In particular, Cas9 plays a major role in using the short RNA as a guide to search for any DNA sequences in viruses and plasmids that match the RNA sequence, cleaving and destroying them. Although the CRISPR pathway has been extensively studied, the mechanism of new spacer acquisition is still poorly understood. In 2015, it was discovered that four proteins Cas1, Cas2, Csn2 and Cas9 are involved in acquiring these spacers in the bacteria Streptococcus pyogenes. Using a combination of biochemical and molecular biology approaches, I will be purifying these proteins separately, studying how the four proteins interact, and visualizing this hypothetical complex via electron microscopy. The discovery that Cas9 is an RNA-guided DNA nuclease has revolutionized biology for its use in genome editing and many other biotechnology applications. This summers research will explore a potentially new function of Cas9 that could lead to development of new Cas9-based biotechnology tools based off of interactions with these other discovered proteins. Ideally, my summer research will help paint a better picture of the mechanisms behind Cas9s revolutionary genome-editing abilities and hopefully shape its role in bioengineering and biotechnology.
Message to Sponsor
- Major: Microbial Biology
- Sponsor: Rose Hills
- Mentor: Jennifer Doudna, Molecular & Cell Biology