Ebola Virus Matrix Protein VP40 Single Mutations G198R and G201R Significantly Enhance Plasma Membrane Localization

Viral proteins frequently undergo single or multiple
amino acid
mutations during replication, which can significantly alter their
functionality. The Ebola virus matrix protein VP40 is multifunctional
but primarily responsible for creating the viral envelope by binding
to the inner leaflet of the host cell plasma membrane (PM). Changes
to the VP40 surface cationic charge via mutations can influence PM
interactions, resulting in altered viral assembly and budding. A recent
mutagenesis study evaluated the effects of several mutations and found
that mutations G198R and G201R enhanced VP40 assembly at the PM and
virus-like particle budding. These two mutations lie in the loop region
of the C-terminal domain (CTD), which directly interacts with the
PM. To understand the role of these mutations in PM localization at
the molecular level, we performed both all-atom and coarse-grained
molecular dynamics simulations using a dimer–dimer configuration
of VP40, which contains the CTD–CTD interface. Our studies
indicate that the location of mutations on the outer surface of the
CTD regions can lead to changes in membrane binding orientation and
degree of membrane penetration. Direct PI(4,5)P2 interactions
with the mutated residues seem to further stabilize and pull VP40
into the PM, thereby enhancing interactions with numerous amino acids
that were otherwise infrequently or completely inaccessible. These
multiscale computational studies provide new insights at the atomic
and molecular level as to how VP40–PM interactions are altered
through single amino acid mutations. Given the high case fatality
rates associated with Ebola virus disease in humans, it is essential
to explore the mechanisms of viral assembly in the presence of mutations
to mitigate the severity of the disease and understand the potential
of future outbreaks.