A Conserved Tryptophan in the Ebola Virus Matrix Protein C-Terminal Domain Is Required for Efficient Virus-Like Particle Formation.

Kristen Johnson,Melissa Budicini,Bernard Gerstman,Rudramani Pokhrel,Prem Chapagain,Robert Stahelin

doi:10.3390/pathogens9050402

Abstract

The Ebola virus (EBOV) harbors seven genes, one of which is the matrix protein eVP40, a peripheral protein that is sufficient to induce the formation of virus-like particles from the host cell plasma membrane. eVP40 can form different structures to fulfil different functions during the viral life cycle, although the structural dynamics of eVP40 that warrant dimer, hexamer, and octamer formation are still poorly understood. eVP40 has two conserved Trp residues at positions 95 and 191. The role of Trp95 has been characterized in depth as it serves as an important residue in eVP40 oligomer formation. To gain insight into the functional role of Trp191 in eVP40, we prepared mutations of Trp191 (W191A or W191F) to determine the effects of mutation on eVP40 plasma membrane localization and budding as well as eVP40 oligomerization. These in vitro and cellular experiments were complemented by molecular dynamics simulations of the wild-type (WT) eVP40 structure versus that of W191A. Taken together, Trp is shown to be a critical amino acid at position 191 as mutation to Ala reduces the ability of VP40 to localize to the plasma membrane inner leaflet and form new virus-like particles. Further, mutation of Trp191 to Ala or Phe shifted the in vitro equilibrium to the octamer form by destabilizing Trp191 interactions with nearby residues. This study has shed new light on the importance of interdomain interactions in stability of the eVP40 structure and the critical nature of timing of eVP40 oligomerization for plasma membrane localization and viral budding.

Highlights

The Ebola virus (EBOV) was first discovered in 1976 following an outbreak of hemorrhagic fever near the Ebola River in Zaire [1]
The EBOV matrix protein has been the subject of much study as it is required for formation of the
Structure function have shed light on lipid binding residues required for plasma membrane binding or localizationstudies as wellof have shed light on lipidAdditional binding residues required for plasma membrane binding or aseVP40

Summary

Introduction

The Ebola virus (EBOV) was first discovered in 1976 following an outbreak of hemorrhagic fever near the Ebola River in Zaire [1]. Since that time there have been sporadic outbreaks in Africa including the largest EBOV outbreak in history in Western Africa (2014–2016) and a current outbreak in the Democratic Republic of Congo. EBOV causes significant disease pathologies such as hemorrhage and organ failure and often has a fatality rate >50% [2]. While there are not yet FDA or WHO approved drugs or antibodies for disease treatment, a vaccine was approved in December of 2019 [3]. EBOV is a filamentous lipid enveloped virus from the Filoviridae family. EBOV harbors a negative sense RNA genome that encodes seven genes [4] and the replication and formation of new virus

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Conclusion