Exploring Diverse Mechanisms of Type III CRISPR-Cas signaling.

Rutgers Biomedical And Health Sciences, Newark NJ

Investigators

Abstract

PROJECT SUMMARY Exploring Diverse Mechanisms of Type III CRISPR-Cas signaling Microbes called bacteria and archaea are the most abundant organisms on Earth and play an essential role in our health and well-being. Like us, they use sophisticated mechanisms to defend themselves from viral infection. Our proposed research focuses on molecular mechanisms of adaptive immunity in prokaryotes, which is mediated by CRISPR-Cas systems. These pathways use RNA-guided interference complexes to target complementary sequences in foreign DNA or RNA for degradation, leading to immunity against phages and other mobile genetic elements. Recent studies on widespread Type III CRISPR-Cas systems show that their RNA-guided interference complexes not only degrade nucleic acids, but also produce cyclic oligoadenylates that act as second messenger molecules to activate a network of signaling effectors, including nucleases, proteases, and membrane proteins. While a diverse array of Type III CRISPR signaling effectors have been identified bioinformatically, our understanding of their function and mechanism remains limited. Our lab aims to understand the mechanisms underlying the function and regulation of these signaling effectors, focusing on two major groups: 1) nucleases, which are the largest group of signaling effectors associated with Type III CRISPR systems, and 2) membrane proteins, since they represent a fascinating new frontier of CRISPR-Cas tools and microbial defense biology. We plan to use biochemistry and structural biology to investigate how signaling effector nucleases are regulated by cyclic nucleotide second messenger molecules. Membrane proteins that are associated with Type III CRISPR-Cas systems also suggest intriguing new connections between RNA-guided antiviral immunity and cellular membrane processes in microbes. We hypothesize that CRISPR-associated membrane proteins perturb membrane integrity to cause cell death, and aim to use a combination of biochemistry, cell biology, and structural biology tools to define the function, mechanism, and regulation of these proteins. Taken together, this has the potential to reveal insights that could redefine paradigms for antiviral defense, as well as spur the development of novel point-of-care diagnostics, RNA sensors, and tools for controlling cell behavior.