title: The P25 pathogenicity factor of Beet necrotic yellow vein virus targets the sugar beet 26S proteasome involved in the induction of a hypersensitive resistance response via interaction with an F-box protein.
abstract: P25, a Beet necrotic yellow vein virus (BNYVV) pathogenicity factor, interacts with a sugar beet protein with high homology to Arabidopsis thaliana kelch repeat containing F-box family proteins (FBK) of unknown function in yeast. FBK are members of the Skp1-Cullin-F-box (SCF) complex that mediate protein degradation. Here, we confirm this sugar beet FBK-P25 interaction in vivo and in vitro and provide evidence for in planta interaction and similar subcellular distribution in Nicotiana tabacum leaf cells. P25 even interacts with an FBK from A. thaliana, a BNYVV nonhost. FBK functional classification was possible by demonstrating the interaction with A. thaliana orthologs of Skp1-like (ASK) genes, a member of the SCF E3 ligase. By means of a yeast two-hybrid bridging assay, a direct effect of P25 on SCF-complex formation involving ASK1 protein was demonstrated. FBK transient Agrobacterium tumefaciens-mediated expression in N. benthamiana leaves induced a hypersensitive response. The full-length F-box protein consists of one F-box domain followed by two kelch repeats, which alone were unable to interact with P25 in yeast and did not lead to cell-death induction. The results support the idea that P25 is involved in virus pathogenicity in sugar beet and suggest suppression of resistance response.
authors.affiliation: Department of Phytopathology, Institute of Sugar Beet Research, Gottingen, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Thiel
authors.forename: Kamal
authors.initials: K
authors.lastname: Hleibieh
authors.forename: David
authors.initials: D
authors.lastname: Gilmer
authors.forename: Mark
authors.initials: M
authors.lastname: Varrelmann
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D027461:Beta vulgaris / Q000378:metabolism* / Q000821:virology*; D060467:Disease Resistance; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000821:virology; D018515:Plant Leaves / Q000378:metabolism / Q000821:virology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D010942:Plant Viruses / Q000472:pathogenicity*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D060066:Protein Interaction Maps; D017434:Protein Structure, Tertiary; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions; D014026:Nicotiana / Q000378:metabolism / Q000821:virology; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C120363:ASK1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D044783:F-Box Proteins; D010940:Plant Proteins; D014764:Viral Proteins; D037521:Virulence Factors; C484058:ASK2 protein, Arabidopsis; D044843:SKP Cullin F-Box Protein Ligases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease