Mechanisms of Nucleic Acid Immunogenicity - Project Summary/Abstract The proposed research seeks to elucidate the structural and mechanistic basis of RNA-dependent innate immune antiviral proteins regulation that stop translation to curb viral infection. The proposal employs a synergistic combination of structural biology (X-ray crystallography, cryo-EM), biochemical analyses (kinase, RNA cleavage assay) and biophysical methods (fluorescence polarization, smFRET, calorimetry) to understand how viral RNA structures inhibit the double-stranded RNA activated protein kinase R (PKR, Aim 1) and the 2´- 5´-oligoadenylate synthases/endoribonuclease RNase L pathway (Aim 2) to escape the immune response, as well as the mechanism of interferon induced protein with tetratricopeptide 1 (IFIT1) induced translation control (Aim 3). Completion of the proposed research will not only produce critical insights into host-virus interplay and host translation control, but will also reveal novel principles of riboregulation. Such in-depth mechanistic understanding will provide a solid foundation for future work to design functional RNA devices that elicit specific functions of PKR and OAS/RNase L, with potential applications in the treatment of infectious and autoimmune and inflammatory diseases that are severe and costly threats to public health. Upon transition to independence, the research findings from this proposal will form the basis of the candidate’s first R01 funding application. The candidate seeks to acquire additional mentored research and career development training through a detailed plan tailored to his specific training deficiencies and proposed research outside of his current expertise. Such requested training in the mentored phase, wholly funded by the NIH Division of Intramural Research, will enable him to become a successful principal investigator upon his transition into research independence. The K99-R00 award will provide excellent opportunities for the candidate to acquire concepts and research skills new to him through a combination of formal course work, hands-on training, and frequent discussions and evaluations with his co-mentoring team formed of five internationally renowned intramural and extramural scientists. The major new research skills to be acquired include cryo-EM, smFRET and eukaryotic protein expression. In consultation with his mentors and advisors, the candidate has developed a detailed career development plan that is tailored to remedy his specific deficiencies in teaching, mentoring, lab management, and career development skills. The plan includes a mentoring course followed by mentoring a NIDDK post-baccalaureate assigned to him, a leadership and management course, and systematic trainings in career development skills including career counseling and assessment, mock interviews, practice job and chalk talks.