Among the (+)ssRNA eukaryotic viruses, flexible filamentous plant viruses are plant pathogens that contain a monopartite (+)ssRNA genome protected by hundreds of copies of their coat protein (CP) arranged in helical mode.
Among the (+)ssRNA eukaryotic viruses, flexible filamentous plant viruses are plant pathogens that contain a monopartite (+)ssRNA genome protected by hundreds of copies of their coat protein (CP) arranged in helical mode. Their infective particles are long (several hundreds of nm) and thin (10-15 nm diameter) flexible filaments. They are transmitted by mechanical contact or mediated by vectors (usually insects) and cause severe economic impact in agriculture. Currently there are more than 400 species grouped in four families: Alphaflexiviridae, Betaflexiviridae, Closteroviridae, and Potyviridae. All these plant viruses display a very similar architecture for their non-enveloped and filamentous virions. The recent developments in cryo-electron microscopy (cryoEM) field allow to obtain near-atomic (≤ 4Å) or atomic resolution using the so-called single particle approach. In recent years, by using single-particle based helical reconstruction of cryoEM data, several virions have been characterized at high structural detail. Our research team has contributed significantly in this field with the description of the first structures for a potexvirus (PepMV) and for two potyviruses (WMV and TuMV). The available structures allowed for comparison between representatives of different families. Remarkably, despite the low sequence identity between CPs from these two different families, PepMV (Alphaflexiviridae) and WMV (Potyviridae) virions display almost identical helical arrangement with about 34.5-35 Å of helical pitch and 8.8 subunits per turn in left-handed helices. In both, potexviruses and potyviruses, the CP in the virion binds to five nucleotides of the ssRNA in a very similar mode and one out of the five nucleotides bound by each CP fits in a binding pocket. Here, three amino acids, serine (S), arginine (R) and aspartic acid (D), that participate in the ssRNA binding pocket are at the same position in the three-dimensional structure of the CPs of these viruses. This set of amino acids are universally conserved along the four families of flexible filamentous plant viruses. This RNA binding pocket is clearly a potential target for the development of compounds for the chemical control for this group of viruses.
Fecha del seminario: 12/01/2022 12:00
Lugar del seminario: Salón de Actos
Ponente del seminario: Mikel Valle
