Description: RNA-guided, or ribonucleoprotein particle (RNP), enzymes comprise an emerging class of
molecules that function in a wide range of biological pathways. Unlike most of the protein-based enzymes,
RNP enzymes rely on the guide RNA to secure the substrates and on the partner proteins to catalyze
the chemical reactions. The RNA-guided targeting mechanism has created unprecedented opportunities
in genome manipulation, gene regulation and nucleic acid detection. Research in the Li laboratory
employs structural biology and complementary methods to uncover the theoretical basis for their
biological function and effective use as research, diagnostic and therapeutic tools. In the proposed
funding period, the Li laboratory will tackle the mechanisms of the RNP enzymes to enable their
applications. These include the methylation-sensitive Clustered, Regularly Interspaced, Short
Palindromic Repeats (CRISPR)-Cas9, the multi-functional Type III CRISPR effectors and their associated
signaling processes, and the small nucleolar RNPs (snoRNPs) responsible for chemical modifications of
ribosomal RNA. Though unrelated in enzyme composition or biological pathway, these RNP enzymes
are governed by a similar set of physicochemical principles and share the great potential in therapeutic
and diagnostic innovations by reprogramming the chemistry of cellular nucleic acids. The proposed
research will assess the feasibility of engineering and applying the epigenetic DNA-specific Cas9, the
utility of rapid virus detection with the CRISPR Type III effectors, and the possibility of tunning cellular
functions through chemical modifications of RNA. The Li laboratory has assembled a team of scientists
with complementary expertise in microbiology, mammalian genome biology, yeast genetics, single
molecule biophysics, virology, virus detection, X-ray crystallography, and high-throughput cryogenic
electron microscopy to maximize the impact while mitigating the risks of the research. The goal of this
transformative proposal is to demonstrate and enable the applicability of the RNA-mediated enzymes in
a wide range of biomedical fields.