Studying the role of capsid protein of Odontoglossum ringspot virus in virus systemic movement and identifying a novel CP- interacting tobacco protein, p26/proteinase inhibitor
Date Issued
2011
Date
2011
Author(s)
Lin, Pin-Chun
Abstract
The capsid protein (CP) of tobamoviruses has been demonstrated to involve in virus systemic movement. However, the CP-mediated systemic movement mechanism is unclear. Our previous results indicated that E100 in the CP (CPE100) of Odotoglossum ringspot virus (ORSV) plays an important role in virus long-distance movement in Nicotiana benthamiana plant. In order to study the effect of E100 on CP-mediated function, this amino acid was mutated to A100 in an ORSV infectious clone (pORSV-7) to create a mutant clone (pORSV-7E100A) with a distinguishable RFLP marker. The results indicated that ORSVE100A could be detected in the infected protoplasts and the inoculated leaves of N. benthamiana and Chenopodium quinoa but lost its systemic infectivity in N. benthamiana plant. The data of in vitro protein binding assay, observation through transmission electron microscopy and size-exclusion chromatography (SEC) showed that the CP produced by pORSV-7E100A (CPE100A) might affect the CP-CP interaction and resulted in viral particle assembly deficiency in planta. Moreover, the differential CP-CP interaction ability between CPWT and CPE100A could explain the good protection to ORSV infection by transient-expressing the CPWT in N. benthamiana, whereas poor protection on the CPE100A-expressing plants. ORSV CP-specific IgG was used for immunoprecipitation of the CP to identify the CP-interacting proteins. Here, several putative host proteins were identified to interact with ORSV CP through mass spectrometry analysis. Among them, a defense-related p26/proteinase inhibitor of N. benthamiana was proved to be highly associated with CP by in vitro pull-down assay. This is the first report of plant p26/proteinase inhibitor interacting with ORSV CP and might interfere with virus systemic movement. The viral particle assembly and the ORSV CP-interacting host proteins will help us to understand the virus movement in plant and also the plant-virus interaction.
Subjects
Odotoglossum ringspot virus (ORSV)
capsid protein
systemic movement
viral particle assemble
virus protection
co-immunoprecipitation
plant-virus interaction
mass spectrometry
proteinase inhibitor
Type
thesis
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