Vertebrates rely on innate immune receptors to sense conserved structures from invading microbes. The overall goal of this project is to understand at the molecular level how innate immune receptors recognize flaviviruses, and how this recognition is translated into an immune response. We focus on innate immune recognition of viral genomic RNA in the cytoplasm by the DExD/H-box RNA helicases RIG-I and MDA5. RIGI recognizes short RNA oligonucleotides bearing 5'-triphosphates, while MDA5 recognizes longer, double stranded RNAs. Our first goal is to measure the binding affinities of RIG-I and MDA5 for RNA substrates of various lengths and secondary structures. We will begin to dissect the mechanism of signal transduction of RIG-I and MDA5 by measuring their rates of ATP hydrolysis and their helicase activities in the presence of their preferred RNA substrates. In the major part of our proposal, we will determine the crystal structures of RIG-I and MDA5 in the presence and absence of their preferred RNA ligands. These crystal structures will reveal the conformational changes caused by RNA binding, which will allow us to understand how binding of RNA is translated into an innate immune signal. To test our structure-based model for signal generation, we will engineer mutations designed to alter the signaling and ligand-binding properties of RIG-I and MDA5. Intracellular signaling in response to viral genomic RNA is modulated by another DExD/H-box helicase, LGP2, which interacts directly with RIG-I and MDA5. To understand how LGP2 regulates RIG-I and MDA5 signaling, we will determine the crystal structure of LGP2 in complex with RIG-I or MDA5. Paramyxoviruses inhibit MDA5 signaling by binding MDA5 directly with their V proteins. In order to understand the molecular basis of this viral immune evasion, we will determine the crystal structure of MDA5 in complex with SV5 V. Our structural approach will provide unique mechanistic insights into the generation and regulation of viral RNA sensing by RIG-I and MDA5. In the long term, this work will guide the rational design of novel vaccine adjuvants and immunomodulatory therapeutics targeting RIG-I or MDA5, thus providing new strategies for the prevention and treatment of viral infections.
Our work will provide a detailed understanding at the molecular level of how the innate immune system recognizes genetic material from certain important viral pathogens, including dengue and West Nile viruses, which afftect approximately 100 million people each year and are rapidly spreading. This project will provide some of the necessary tools to create novel therapeutics against these pathogens, such as less toxic vaccine adjuvants, and anti-inflammatory drugs targeting the innate immune response.
|Warkentin, Matthew; Hopkins, Jesse B; Haber, Jonah B et al. (2014) Temperature-dependent radiation sensitivity and order of 70S ribosome crystals. Acta Crystallogr D Biol Crystallogr 70:2890-6|
|Wang, Jimin; Wing, Richard A (2014) Diamonds in the rough: a strong case for the inclusion of weak-intensity X-ray diffraction data. Acta Crystallogr D Biol Crystallogr 70:1491-7|
|Roth, Adam; Weinberg, Zasha; Chen, Andy G Y et al. (2014) A widespread self-cleaving ribozyme class is revealed by bioinformatics. Nat Chem Biol 10:56-60|
|Wang, Jimin; Li, Yue; Modis, Yorgo (2014) Exploiting subtle structural differences in heavy-atom derivatives for experimental phasing. Acta Crystallogr D Biol Crystallogr 70:1873-83|
|McCown, Phillip J; Liang, Jonathan J; Weinberg, Zasha et al. (2014) Structural, functional, and taxonomic diversity of three preQ1 riboswitch classes. Chem Biol 21:880-9|
|Polikanov, Yury S; Steitz, Thomas A; Innis, C Axel (2014) A proton wire to couple aminoacyl-tRNA accommodation and peptide-bond formation on the ribosome. Nat Struct Mol Biol 21:787-93|
|Askerka, Mikhail; Wang, Jimin; Brudvig, Gary W et al. (2014) Structural changes in the oxygen-evolving complex of photosystem II induced by the S1 to S2 transition: A combined XRD and QM/MM study. Biochemistry 53:6860-2|
|Polikanov, Yury S; Szal, Teresa; Jiang, Fuyan et al. (2014) Negamycin interferes with decoding and translocation by simultaneous interaction with rRNA and tRNA. Mol Cell 56:541-50|
|Wang, Jimin; Li, Yue; Modis, Yorgo (2014) Structural models of the membrane anchors of envelope glycoproteins E1 and E2 from pestiviruses. Virology 454-455:93-101|
|Nelson, James W; Sudarsan, Narasimhan; Furukawa, Kazuhiro et al. (2013) Riboswitches in eubacteria sense the second messenger c-di-AMP. Nat Chem Biol 9:834-9|
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