Project Summary: As obligate intracellular pathogens, viruses must hijack cellular machinery to facilitate productive infection. For DNA viruses that depend on host RNA processing machinery to produce viral transcripts, common targets of manipulation include both cellular RNA-binding proteins (RBPs) and the enzymes mediating the post- translational modifications (PTMs) that govern their functions. Arginine methylation is a PTM deposited by a family of protein arginine methyltransferases (PRMTs) and involved in multiple aspects of RNA processing. While the roles of arginine methylation and PRMTs constitute an emerging field in multiple areas of biology, relatively little is known about their functions during viral infection. The objective of this project is to utilize human Adenovirus (AdV) as a model system to address the roles of arginine methylation during infection. AdV is an important human pathogen and also well recognized as a tool for investigating fundamental cellular processes. Preliminary data from the Weitzman lab demonstrate an intriguing global decrease of arginine methylation on cellular RBPs throughout AdV infection. Concurrently, arginine methylation of late region 4 (L4) 100 kDa nonstructural protein (100K) dramatically increases as infection progresses. Furthermore, 100K expression is sufficient to cause relocalization of PRMT1 from its normally nuclear subcellular compartment to the cytoplasm, an event which correlates with a 100K-dependent loss of arginine methylation on cellular RBPs. Additionally, methylation of the host RBP hnRNPA1 decreases in response to 100K expression alone. Arginine methylation of hnRNPA1 is known to regulate its splicing capacity, and AdV is well known to manipulate host splicing machinery, but knowledge of the role of hnRNPA1 during AdV infection is limited. These collective findings inform my hypothesis that 100K acts as a molecular sponge of PRMT1 activity, leading to the loss of arginine methylation of RBPs such as h