title: F-box-like domain in the polerovirus protein P0 is required for silencing suppressor function.
abstract: Plants employ small RNA-mediated posttranscriptional gene silencing as a virus defense mechanism. In response, plant viruses encode proteins that can suppress RNA silencing, but the mode of action of most such proteins is poorly understood. Here, we show that the silencing suppressor protein P0 of two Arabidopsis-infecting poleroviruses interacts by means of a conserved minimal F-box motif with Arabidopsis thaliana orthologs of S-phase kinase-related protein 1 (SKP1), a component of the SCF family of ubiquitin E3 ligases. Point mutations in the F-box-like motif abolished the P0-SKP1 ortholog interaction, diminished virus pathogenicity, and inhibited the silencing suppressor activity of P0. Knockdown of expression of a SKP1 ortholog in Nicotiana benthamiana rendered the plants resistant to polerovirus infection. Together, the results support a model in which P0 acts as an F-box protein that targets an essential component of the host posttranscriptional gene silencing machinery.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, 12 Rue du Général Zimmer, 67084 Strasbourg, France.
authors.forename: Maghsoud
authors.initials: M
authors.lastname: Pazhouhandeh
authors.forename: Monika
authors.initials: M
authors.lastname: Dieterle
authors.forename: Katia
authors.initials: K
authors.lastname: Marrocco
authors.forename: Esther
authors.initials: E
authors.lastname: Lechner
authors.forename: Bassam
authors.initials: B
authors.lastname: Berry
authors.forename: Véronique
authors.initials: V
authors.lastname: Brault
authors.forename: Odile
authors.initials: O
authors.lastname: Hemmer
authors.forename: Thomas
authors.initials: T
authors.lastname: Kretsch
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Richards
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Véronique
authors.initials: V
authors.lastname: Ziegler-Graff
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D017124:Conserved Sequence; D044782:F-Box Motifs; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010942:Plant Viruses / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C455512:SPIKE1 protein, Arabidopsis; D014764:Viral Proteins