CRISPR systems are RNA-guided microbial adaptive immune systems that have been repurposed for applications in medicine, pharmacology, and agriculture. The hallmark of CRISPR immune systems is the CRISPR sequence contained in the host chromosome, which consists of short direct-repeats of 20-40 bases, followed by unique spacer sequences of about the same length. In 2005 several bioinformatics groups discovered that CRISPR spacer sequences in bacteria and archaea were identical to known microbial pathogens such as viruses and plasmids, suggesting that CRISPRs serve as a molecular memory of encounters with foreign nucleic acid. Since 2005 basic research on these systems has revealed the CRISPR is transcribed and processed into a library of small RNAs. Each CRISPR derived RNA (crRNA) combines with CRISPR associated (Cas) proteins to form ribonucleoprotein complexes that survey the intercellular environment and use the crRNA as a guide to bind complementary DNA or RNA sequences. Once the complex is bound, it elicits an immune response that activates cis- or trans-acting nucleases that destroy the target before it can infect the host. All CRISPR systems follow these general steps to provide immunity, and because CRISPR systems can be programmed with RNA guides to target nucleic acid, they have been repurposed as genome editing tools. However, CRISPR systems are incredibly diverse, and we hypothesize that additional CRISPR-based technologies are waiting to be discovered through basic research. To determine the structure and function of a type IV CRISPR system, we aim to recombine the genetic components of the system into E. coli and express the system. We aim to determine what components are required to provide immunity from nucleic acid hosts, and will attempt to purify CRISPR complexes from these cells to investigate their function in vitro. Our role in this overarching goal is to design and synthesize the CRISPR component of the immune system.
Adams, Michael; Domgaard, Hannah; and Jackson, Ryan, "Design and Construction of Single-Spacer Type-IV CRISPR Sequences" (2017). Biology Posters. Paper 180.