F-box-like domain in the polerovirus protein P0 is required for silencing suppressor function.
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.
Pazhouhandeh
Maghsoud
M
Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, 12 Rue du Général Zimmer, 67084 Strasbourg, France.
Dieterle
Monika
M
Marrocco
Katia
K
Lechner
Esther
E
Berry
Bassam
B
Brault
Véronique
V
Hemmer
Odile
O
Kretsch
Thomas
T
Richards
Kenneth E
KE
Genschik
Pascal
P
Ziegler-Graff
Véronique
V
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*
D029681:Arabidopsis Proteins; C455512:SPIKE1 protein, Arabidopsis; D014764:Viral Proteins