Dissecting the Impact of Viral Biomolecular Condensates on Cellular Translation and RNA Interference (RNAi)

Biomolecular condensates are dynamic, membrane-less organelles formed within cells, and both host cells and viruses encode proteins that can assemble into these structures, facilitating essential cellular processes and viral replication. My laboratory uses model positive-sense, single-stranded RNA viruses (+ssRNA) like Pea enation mosaic virus 2 (PEMV2) and Turnip crinkle virus (TCV) to better understand virus-host interactions that take place in biomolecular condensates. Over the next five years, our objectives encompass several key aspects. Initially, we will investigate the specific mechanisms through which viral condensates, particularly focusing on p26 from PEMV2, disrupt cellular translation. Additionally, we will utilize nanopore sequencing to explore their potential role in interfering with fibrillarin-mediated 2'-O-methylation of ribosomal RNAs. We will use transcriptome-wide methodologies (e.g., TRAP-seq) to comprehensively investigate the impact of viral condensates on the translatome during infection and test the hypothesis that viral condensates promote translational repression of antiviral transcripts while enhancing translation of pro-viral transcripts. Using a similar approach, we will investigate whether viral condensates function as a molecular switch, repressing the translation of viral transcripts to favor late stages of the virus replication cycle, such as packaging and release. Next, we will shift our efforts to understanding how nuclear condensates formed by the coat protein (CP) of TCV inhibit RNA interference (RNAi), potentially via the sequestration of siRNA precursors. We will also investigate whether CP condensates interfere with the epigenetic regulation of siRNAs to alter their stability and host gene expression. Our research program's overarching vision is to employ model systems to understand better how viral biomolecular condensates disrupt cellular homeostasis, ultimately promoting virus fitness. This research addresses a critical knowledge gap by investigating the impact of viral condensates on host cell function, an area that has received limited attention compared to the extensive research on their effects on virus replication. Our research will also yield novel virus-host interactions with potential applicability across RNA virus families, potentially serving as a foundation for developing innovative therapeutics.