An original structural fold underlies the multitask P1, a silencing suppressor encoded by the Rice yellow mottle virus

The Rice Yellow Mottle sobemovirus (RYMV) belongs to the most damaging pathogens devastating rice fields in Africa. P1, a key protein for RYMV, was reported as a potent RNAi suppressor counteracting RNA silencing in plant reporter systems. Here we describe the complete 3D structure and dynamics of P1. Its N-terminal region contains ZnF1, a structural CCCC-type zinc finger strongly affine to zinc and a prominent short helix, rendering this region poorly amenable to structural changes. P1 C-terminal region contains ZnF2, an atypical HCHC-type ZnF that does not belong to any existing class of Zn finger proteins. ZnF2 appeared much less affine to zinc and more sensitive to oxidizing environments than ZnF1, and may serve as a sensor of plant redox status. We also identified key residues essential for RYMV infectivity and spread in rice tissues through their participation in P1 oligomerization and folding.Altogether, our results provide the first complete structure of a rice antiviral silencing suppressor and highlight P1 structural properties that may serve RYMV functions to infect and invade the host plant.

Vianney Poignavent (1) , François Hoh (2) , Guillaume Terral (3) , Yang Yinshan (2) , François-Xavier Gillet (1) , Jeong-Hyeon Kim (1) , Frédéric Allemand (4) , Eric Lacombe (1) , Christophe Brugidou (1) , Sarah Cianférani (3) , Héléne Démèné (4) , Florence Vignols (5)

1 UMR IPME - UMR - Interactions Plantes Microorganismes Environnement
2 CBS - Centre de Biochimie Structurale [Montpellier]
3 LSMBO - Laboratoire de Spectrométrie de Masse BioOrganique [Strasbourg]
4 BCM - BioCampus
5 BPMP - Biochimie et Physiologie Moléculaire des Plantes

The Rice Yellow Mottle sobemovirus (RYMV) belongs to the most damaging pathogens devastating rice fields in Africa. P1, a key protein for RYMV, was reported as a potent RNAi suppressor counteracting RNA silencing in plant reporter systems. Here we describe the complete 3D structure and dynamics of P1. Its N-terminal region contains ZnF1, a structural CCCC-type zinc finger strongly affine to zinc and a prominent short helix, rendering this region poorly amenable to structural changes. P1 C-terminal region contains ZnF2, an atypical HCHC-type ZnF that does not belong to any existing class of Zn finger proteins. ZnF2 appeared much less affine to zinc and more sensitive to oxidizing environments than ZnF1, and may serve as a sensor of plant redox status. The structure helped us to identify key residues essential for RYMV infectivity and spread in rice tissues through their participation in P1 oligomerization and folding. Altogether, our results provide the first complete structure of an antiviral silencing suppressor encoded by a virus infecting rice and highlight P1 structural and dynamical properties that may serve RYMV functions to infect and invade its host plant.

Domaines: Sciences du Vivant [q-bio]; Biologie végétale

Vianney Poignavent, François Hoh, Guillaume Terral, Yang Yinshan, François-Xavier Gillet, et al.. An original structural fold underlies the multitask P1, a silencing suppressor encoded by the Rice yellow mottle virus. 2020. ⟨hal-03076418⟩