The RNA Silencing Suppressor P8 From High Plains Wheat Mosaic Virus is a Functional Tetramer.

Autor: Hamo S; Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel., Izhaki-Tavor LS; Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel., Tatineni S; USDA-ARS and Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, United States., Dessau M; Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel. Electronic address: moshe.dessau@biu.ac.il.
Jazyk: angličtina
Zdroj: Journal of molecular biology [J Mol Biol] 2024 Dec 15; Vol. 436 (24), pp. 168870. Date of Electronic Publication: 2024 Nov 20.
DOI: 10.1016/j.jmb.2024.168870
Abstrakt: In plants, RNA interference (RNAi) serves as a critical defense mechanism against viral infections by regulating gene expression. However, viruses have developed RNA silencing suppressor (RSS) proteins to evade this defense mechanism. The High Plains wheat mosaic virus (HPWMoV) is responsible for the High Plains disease in wheat and produces P7 and P8 proteins, which act as RNA silencing suppressors. P8, in particular, lacks sequence similarity to known suppressors, prompting inquiries into its structure and function. Here, we present a comprehensive analysis of P8, elucidating its structure and function. Using X-ray crystallography, we resolved the full-length P8 structure at 1.9 Å resolution, revealing a tetrameric arrangement formed by two identical dimers. Through structure-based mutagenesis, biochemical assays, and functional studies in plants, we demonstrate that HPWMoV P8's RNA silencing suppression activity relies on its oligomeric state. Contrary to previous report, our findings indicate that while a P8 fused to maltose-binding protein (MBP-P8) was hypothesized to bind short double-stranded RNA, the native P8 tetramer does not interact with small interfering RNA (siRNA). This suggests an alternative mechanism for its function, yet to be determined. Our study sheds light on the structural and functional characteristics of HPWMoV P8, providing valuable insights into the complex interplay between viral suppressors and host defense mechanisms. SIGNIFICANCE STATEMENT: Effective action to address malnutrition in all its forms requires an understanding of the mechanisms affecting it. Wheat, crucial for human and animal consumption, faces threats from biotic and abiotic stresses. RNA silencing is a key defense against viral infections in plants. Plant viruses employ various mechanisms, including encoding viral RNA silencing suppression (VRS) proteins, to evade host immune responses. Despite the conservation of RNA-silencing pathways, viral RSS proteins exhibit diverse sequences, structures, and mechanisms. Our study focuses on P8, an RSS protein from HPWMoV. Understanding its structure and assembly is a crucial step toward comprehending how these viruses counteract host defenses, aiding in combatting malnutrition.
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 © 2024 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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