Self-Assembly and Packaging of RNA and DNA in Viruses and Virus-like Particles

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With this grant, the Chemistry of Life Processes program is supporting the research of Professors William M. Gelbart and Charles M. Knobler in the Department of Chemistry and Biochemistry at UCLA on in vitro investigations of viral self-assembly and packaging processes. This project is being co-funded by the Genetic Mechanisms Cluster in the Molecular and Cellular Biosciences Division of the BIO Directorate. For the dsDNA case, single-particle experiments with bacteriophage lambda are designed to test the hypothesis that pressure-driven genome ejection can be completed by active processes like transcription by RNA polymerase. For the ssRNA case, a particular genus of simple plant virus, the well-characterized bromoviruses, is chosen as the model system. Experiments will be performed to measure the relative packaging efficiencies of a broad range of ssRNA molecules, viral, and non-viral, in order to discover the competing roles played by RNA charge, size, and shape. Further, to understand the evolutionary connection between these plant viruses and present-day mammalian counterparts such as the alphaviruses and flaviviruses, an attempt will be made to package these mammalian RNA genomes with plant capsid protein and to wrap the resulting nucleocapsids with phospholipid bilayer, in order to mimic enveloped viruses like dengue and hepatitis C.On a fundamental level, this research seeks to build a strong foundation for a physical understanding of viral infectivity. The emerging field of "Physical Virology" is contributing to the training of a new cadre of interdisciplinary science students and researchers who are equipped to apply fundamental ideas, approaches and techniques from chemistry and physics to basic biological problems like viral replication. Two new courses on general aspects of viruses have been taught to non-science undergraduate majors, and an outreach program has been developed for local high school students and teachers, exposing them to virus related research at UCLA and providing model-building and visualization projects for the classroom. In the longer term, this basic research may contribute to new approaches to anti-viral therapies based upon interference with the self-assembly of the ssRNA/capsid protein nucleocapsid and/or its wrapping by the lipid envelope.