Grace Uwase
Program: Molecular Microbiology and Microbial Pathogenesis
Current advisor: Gaya K. Amarasinghe, PhD
Undergraduate university: Colby College
Research summary
Ebola virus (EBOV) is a non-segmented, negative-sense RNA virus with a single-stranded genome. Due to its limited protein-coding capacity, EBOV relies on multifunctional viral proteins and host factors to facilitate viral replication and pathogenesis. Among the proteins it encodes, the multifunctional VP35 plays a critical role in both immune evasion and viral RNA synthesis. Proteomics studies have uncovered numerous VP35-host protein interactions and highlighted the complex role of VP35 in modulating host cellular processes. To understand the role of VP35 in pathogenesis, its regulation, and its therapeutic potential, it is essential to systematically analyze each VP35 binding partner by: (1) precisely mapping the regions of VP35 involved in these interactions, (2) determining their roles in EBOV replication and immune evasion, and (3) characterizing the temporal and spatial dynamics of these interactions during infection. In this study, we employed biochemical, structural, and cell biology approaches to characterize the interaction between VP35 and a novel host binding partner, the E3 ubiquitin ligase Mindbomb 2 (MIB2).
We identified a previously uncharacterized NNLNS motif within VP35 that serves as the binding site for MIB2. We demonstrate that this motif contributes to RNA synthesis and that MIB2 binding to VP35 inhibits EBOV polymerase activity. We found that MIB2 can ubiquitinate VP35, although the specific ubiquitination sites and functional consequences remain to be elucidated. We also determined that VP35 interacts with the N-terminal MZM and MREP domains, providing new insights into MIB2 domain organization and structure. VP35 binding to MIB2 promotes immune evasion by inhibiting MIB2-mediated interferon induction, which has an additive effect to previously established VP35 immune evasion through dsRNA binding. Finally, we show that VP35 may promote cell death by impairing MIB2-mediated apoptosis regulation. These findings improve our understanding of the multifunctional nature of VP35 and offer insights into the roles of previously uncharacterized intrinsically disordered regions (IDRs). This study underscores the importance of characterizing host-virus interactions to uncover novel mechanisms in viral and host biology.
Graduate publications
Mittal E, Skowyra ML, Uwase G, Tinaztepe E, Mehra A, Köster S, Hanson PI, Philips JA. 2018 Mycobacterium tuberculosis Type VII Secretion System Effectors Differentially Impact the ESCRT Endomembrane Damage Response. mBio, 9(6):pii: e01765-1.