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Viruses of the sobemovirus genus are plant viruses, most of which generate very important agricultural and financial losses. Among them, the rice yellow mottle virus (RYMV) is one of the most damaging pathogens devastating rice fields in Africa. RYMV infectivity and propagation rely on its protein P1, identified as a key movement and potential long-distance RNA silencing suppressor. Here we describe P1's complete 3D structure and dynamics obtained by an integrative approach combining X-Ray crystallography and NMR spectroscopy. We show that P1 is organized in two semi-independent and topologically unrelated domains, each harboring an original zinc finger. The two domains exhibit different affinities for zinc and sensitivities to oxidoreduction conditions, making the C-terminal P1 region a potential labile sensor of the plant redox status. An additional level of regulation resides on the capacity of P1 to oligomerize through its N-terminal domain. Coupling P1 structure information with site-directed mutagenesis and plant functional assays, we identified key residues in each zinc domain essential for infectivity and spread in rice tissues. Altogether, our results provide the first complete structure of a sobemoviral P1 movement protein and highlight structural and dynamical properties that may serve RYMV functions to infect and invade its host plant., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Viral suppressors of RNA interference (VSRs) target host gene silencing pathways, thereby operating important roles in the viral cycle and in host cells, in which they counteract host innate immune responses. However, the molecular mechanisms of VSRs are poorly understood. We provide here biochemical and biophysical features of the dual suppressor/activator VSR P1 protein encoded by the rice yellow mottle virus. In silico analyses of P1 suggested common features with zinc finger proteins and native mass spectrometry unambiguously confirmed that recombinant P1 binds reversibly two zinc atoms, each with a different strength. Additionally, we demonstrate that the reaction of P1 with H2O2 leads to zinc release, disulfide bond formation, and protein oligomerization. A reversible protein modification by redox alterations has only been described for a limited number of zinc finger proteins and has never been reported for VSRs. Those reported here for P1 might be a general feature of Cys-rich VSRs and could be a key regulatory mechanism for the control of RNA silencing., (Copyright © 2013. Published by Elsevier Ltd.)