title: Nonstructural protein P7-2 encoded by Rice black-streaked dwarf virus interacts with SKP1, a core subunit of SCF ubiquitin ligase.
abstract: BACKGROUND
  Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus within the family Reoviridae, causes severe damage to cereal crops in South East Asia. The protein P7-2, encoded by the second open reading frame of segment S7, is conserved among most plant-infecting fijiviruses, but its function is still obscure.
  
  
  RESULTS
  In this study, P7-2 was used as bait in two-hybrid screens of a cDNA library expressing Zea mays proteins. It was found that there is a strong interaction between P7-2 and Z. mays SKP1 (SKP1Maize), a core subunit of the multicomponent SCF (SKP1/Cullin1/F-box/Rbx1) E3 ubiquitin ligase. The interaction was then confirmed in leaf epidermal cells of Nicotiana benthamiana by bimolecular fluorescence complementation assay. Further investigations indicated that P7-2 also interacts with SKP1 proteins from other plants, including Arabidopsis thaliana, N. benthamiana,Oryza sativa and Saccharum sinense. The C-terminal fragment of SKP1Maize (residues 97-176) and the middle fragment of P7-2 (residues 79-214) are necessary to sustain the interaction, while the C-terminal putative α-helix domain spanning residues 214-295 of P7-2 greatly facilitates the interaction. Agrobacterium-mediated transient suppression assay showed that P7-2 has no obvious activity to suppress local RNA silencing.
  
  
  CONCLUSIONS
  Taken together, our results indicated that RBSDV P7-2 can interact with SKP1 proteins from different plants. This is the first report linking a Fijivirus protein to a component of the ubiquitin proteasome system. P7-2 might be a potential F-box protein encoded by RBSDV and involved in the plant-virus interaction through ubiquitination pathway.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Han
authors.forename: Xiangru
authors.initials: X
authors.lastname: Chen
authors.forename: Zaifeng
authors.initials: Z
authors.lastname: Fan
authors.forename: Dawei
authors.initials: D
authors.lastname: Li
authors.forename: Jialin
authors.initials: J
authors.lastname: Yu
authors.affiliation: State Key Laboratory for Agro-biotechnology and Ministry of Agriculture Key Laboratory for Plant Pathology, China Agricultural University, Beijing 100193, P, R, China. hanchenggui@cau.edu.cn.
authors.forename: Chenggui
authors.initials: C
authors.lastname: Han
mesh_terms: D017360:Arabidopsis / Q000821:virology; D054884:Host-Pathogen Interactions; D012275:Oryza / Q000821:virology; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D021122:Protein Subunits / Q000378:metabolism; D012087:Reoviridae / Q000502:physiology*; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D031786:Saccharum / Q000821:virology; D014026:Nicotiana / Q000821:virology; D020798:Two-Hybrid System Techniques; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D003313:Zea mays / Q000502:physiology*
chemical_list: D010940:Plant Proteins; D021122:Protein Subunits; D017361:Viral Nonstructural Proteins; D044843:SKP Cullin F-Box Protein Ligases