Summary of Research Interests
RNA-directed RNA synthesis is essential for survival of numerous prokaryotic and eukaryotic RNA viruses. Despite diverse hosts, many plus-strand RNA viruses exhibit similar mechanisms for various aspects of genome expression. Potato virus X (PVX) is an excellent model system for both genetic and biochemical analyses of RNA synthesis. This virus contains a relatively small, single genomic RNA that is functionally monocistronic and is available as an infectious clone. A protoplast replication system has been developed for quantification of plus- and minus-strand PVX RNA accumulation, which is a powerful system for genetic analyses. Replication of PVX to high levels in tobacco plants has enabled the development of soluble extracts that support template-dependent PVX RNA synthesis and utilization of infected plants for revertant studies. Extensive studies in our laboratory have found that terminal and internal conserved elements and long-distance interactions among these elements are required for synthesis of both minus- and plus-strand RNA in vivo and in vitro. Current research is focused on the role of local elements, long-distance RNA/RNA interactions, and RNA/protein interactions in translation of the viral replicase and subsequent transcription events. Specifically, experiments are underway to determine if RNA/RNA and RNA/protein interactions direct a specific genomic RNA configuration that enhances gene expression, and if assembly of translation and transcription complexes results in further remodeling of this configuration.