The near-atomic cryoEM structure of a flexible filamentous plant virus shows homology of its coat protein with nucleoproteins of animal viruses.

Xabier Agirrezabala,Eduardo Méndez-López,Gorka Lasso,Mikel Valle,M Amelia Sánchez-Pina,Miguel Aranda

doi:10.7554/elife.11795

Abstract

Flexible filamentous viruses include economically important plant pathogens. Their viral particles contain several hundred copies of a helically arrayed coat protein (CP) protecting a (+)ssRNA. We describe here a structure at 3.9 Å resolution, from electron cryomicroscopy, of Pepino mosaic virus (PepMV), a representative of the genus Potexvirus (family Alphaflexiviridae). Our results allow modeling of the CP and its interactions with viral RNA. The overall fold of PepMV CP resembles that of nucleoproteins (NPs) from the genus Phlebovirus (family Bunyaviridae), a group of enveloped (-)ssRNA viruses. The main difference between potexvirus CP and phlebovirus NP is in their C-terminal extensions, which appear to determine the characteristics of the distinct multimeric assemblies - a flexuous, helical rod or a loose ribonucleoprotein. The homology suggests gene transfer between eukaryotic (+) and (-)ssRNA viruses.

Highlights

Flexible filamentous viruses are ubiquitous plant pathogens that have an enormous impact in agriculture (Revers and Garcia, 2015)
The filaments are 120130 Ain diameter, and the coat protein (CP) are arranged following helical symmetry with slightly less than 9 subunits per turn (Kendall et al, 2008). This overall arrangement is shared by Soybean mosaic virus (SMV) a potyvirus, and three different potexviruses, Potato virus X (PVX), Papaya mosaic virus (PapMV), and Narcissus mosaic virus (NMV) (Kendall et al, 2013, Yang et al, 2012, Kendall et al, 2008)
The cryoEM structure of Bamboo mosaic virus (BaMV), another potexvirus, was determined at 5.6 A (DiMaio et al, 2015), and the CP was modeled based on the atomic structure of a Agirrezabala et al eLife 2015;4:e11795

Summary

Introduction

Flexible filamentous viruses are ubiquitous plant pathogens that have an enormous impact in agriculture (Revers and Garcia, 2015). Structural studies of virions by X-ray fiber diffraction and cryoEM have revealed a common architecture for flexible plant viruses. The cryoEM structure of Bamboo mosaic virus (BaMV), another potexvirus, was determined at 5.6 A (DiMaio et al, 2015), and the CP was modeled based on the atomic structure of a Agirrezabala et al eLife 2015;4:e11795.

Results

Conclusion