The project focuses on the role of RAV, a presumptive transcription factor, in mediating the action of a potent viral suppressor of RNA silencing called helper component proteinase (HC-Pro). HC-Pro is a multifunctional viral protein that suppresses RNA silencing and causes anomalies in the biogenesis and function of a number of small regulatory RNAs, including endogenous microRNAs (miRNAs) and the short interfering RNAs (siRNAs) that mediate the RNA silencing process. Preliminary studies indicate that tobacco RAV and the closely related Arabidopsis protein, RAV2, are endogenous regulators of RNA silencing that are required for the for HC-Pro suppression of virus induced silencing but not HC-Pro associated defects in the endogenous small RNA pathways. The first aim of this project addresses the hypothesis that HC-Pro uses RAV2 to regulate the expression of genes required for the suppression of RNA silencing. Genes that are directly regulated by RAV2 will be identified using whole genome tiling arrays and chromatin immunoprecipitation techniques, and the role of these genes in RNA silencing will be assessed by genetic analysis. The second aim of the project is to map the domains of both HC-Pro and RAV2 that are required for their interaction in vivo and in vitro, determine the intracellular localization of RAV2 and whether it is altered in HC-Pro plants. This research is likely to contribute significantly to the understanding of RNA silencing, its interconnection with endogenous small RNA pathways and the mechanisms by which viruses usurp endogenous control systems for counter-defensive purposes.
Outreach: The research will be integrated into the educational system at the University of South Carolina via participation in the University 101 program for first year students, which has received national recognition for excellence, and through summer rotations for undergraduates in research through the auspices of the Undergraduate Research in Integrative Evolutionary Biology (NSF-REU). The educational outreach component of the research plan will emphasize encouragement for female and under-represented minority students and help provide them with an accessible pathway into the research sciences. Once a year the project will participate in a science section of University 101 using the ongoing research as an example of modern scientific inquiry as a means of reaching a broad group of students early in their college experience. In addition, summer internships will include lab work, organized research meetings and a formal presentation of work through the auspices of the Undergraduate Research in Integrative Evolutionary Biology (NSF-REU). Senior personnel on the proposal, as well as the PI, will participate actively in both teaching and mentoring.
