title: Cytorhabdovirus P protein suppresses RISC-mediated cleavage and RNA silencing amplification in planta.
abstract: Plant viruses have evolved to undermine the RNA silencing pathway by expressing suppressor protein(s) that interfere with one or more key components of this antiviral defense. Here we show that the recently identified RNA silencing suppressor (RSS) of lettuce necrotic yellows virus (LNYV), phosphoprotein P, binds to RNA silencing machinery proteins AGO1, AGO2, AGO4, RDR6 and SGS3 in protein-protein interaction assays when transiently expressed. In planta, we demonstrate that LNYV P inhibits miRNA-guided AGO1 cleavage and translational repression, and RDR6/SGS3-dependent amplification of silencing. Analysis of LNYV P deletion mutants identified a C-terminal protein domain essential for both local RNA silencing suppression and interaction with AGO1, AGO2, AGO4, RDR6 and SGS3. In contrast to other viral RSS known to disrupt AGO activity, LNYV P sequence does not contain any recognizable GW/WG or F-box motifs. This suggests that LNYV P may represent a new class of AGO binding proteins.
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Krin S
authors.initials: KS
authors.lastname: Mann
authors.affiliation: School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Karyn N
authors.initials: KN
authors.lastname: Johnson
authors.affiliation: School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Carroll
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, QLD 4072, Australia; School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia. Electronic address: r.dietzgen@uq.edu.au.
authors.forename: Ralf G
authors.initials: RG
authors.lastname: Dietzgen
mesh_terms: D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D012209:Rhabdoviridae / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D060565:Argonaute Proteins; D010940:Plant Proteins; D012367:RNA, Viral; D014764:Viral Proteins
keywords: Agroinfiltration; Argonaute proteins; Lettuce necrotic yellows cytorhabdovirus; Phosphoprotein; Protein–protein interactions; RNA silencing amplification; RNA silencing suppression