Functional Studies Of Ebola Virus Matrix Protein Vp40

Intro: Filoviruses are filamentous viruses and include Ebola (EBOV) and Marburg (MARV), and mortality rates can be has high as 90%. EBOV harbors a genome of 7 proteins, the most abundantly expressed in mature virions is Viral Matrix Protein 40 (VP40). VP40 is required for the assembly and budding of EBOV; VP40 alone can form Virus Like Particles (VLPs) from the plasma membrane (PM) of host cells. VP40 adopts different structures to elicit different functions in the viral life cycle: one for budding from the PM and one for regulation of viral transcription. Objective: We aim to determine lipid composition requirements for functionality of VP40 mutants vs. wild-type, and to elucidate the mechanism of VP40 oligomerization using site-specific mutants. Methods Surface Plasmon Resonance (SPR), Giant Unilamellar Vesicles (GUVs) Results VP40 binds with nanomolar affinity to liposomes containing phosphatidylserine (PS). VP40 requires PS in order to bud from the PM. PS-depleted cells show diminished PM budding that is rescued upon supplementation of PS. Probing lipids with mutants of VP40 have identified regions of VP40 that are integral to PS binding. In vitro assays using GUVs show that WT VP40 is capable of budding vesicles from parent liposomes, while select mutants of VP40 appear to interact differently with parent liposomes. Conclusions A basic patch within the C-terminal region of VP40 likely facilitates lipid binding and budding from host membranes. We hope to elucidate the mechanism of VP40 interactions with the host membrane in order to facilitate the formation of mature virions. Financial Support: NIH AI081077 & T32GM075762