Defining a role and functional consequences of the disordered N-terminal domain from the Borna Disease Virus Phosphoprotein

Project Summary: Defining a role and functional consequences of the disordered N-terminal domain from the Borna Disease Virus Phosphoprotein PI: Madison A. Stringer Borna Disease Virus causes fatal neurological diseases in mammals. Among a handful of proteins in the viral genome, phosphoprotein (P) is an essential component for genome replication. It required for bridging the genome to the polymerase, and this bridging requires an oligomeric form of P. P itself has three domains: the central helical domain is flanked by two intrinsically disordered regions (IDRs). The helical domain binds the polymerase, the C-terminal IDR is required to bind the nucleocapsid protein, and the N-terminal IDR is required for binding RNA and driving the formation of compartmentalized viral factories in the cell. Despite its essential role in genome replication, we know very little about P, and all biochemical studies to date have focused on the folded domain. I hypothesize that the physical properties encoded in the sequence of the IDRs are important to P’s functions. A major knowledge gap is understanding how the N-terminal IDR (NTD) specifically can modulate the functions of P: its self-association, RNA binding, and how oligomerization and RNA binding properties of P can influence the activity and localization of the viral polymerase. My central hypothesis is that the prolines and charged residues in P’s sequence modulate the activities of P by enhancing its self-association and affinity to RNA, ultimately altering L localization and activity in cells. To test this hypothesis, I will use a combination of biochemical and biophysical techniques to characterize the NTD and its interactions. Overall, this proposal aims to biophysically characterize P and use insights from these experiments to allow for mechanistic understanding of its function in cells. At the same time, it will offer a fundamental opportunity to develop skills in single-molecule spectroscopy, cell biology, and virology, fostering the multidisciplinary training needed for my future as an academic biomedical investigator.