An interaction was recently detected between the potyviral protein, genome-linked (VPg) and the Arabidopsis thaliana translation initiation factor eIF(iso)4E (Wittmann et al., 1997). / Here, experiments were undertaken to address biological aspects of the VPg-eIF4E interaction. First, coimmunoprecipitation experiments performed with purified recombinant proteins have shown that VPg not only associates with eIF4E, as was previously published, but also with the larger eIF4F complex, of which eIF4E is a subunit. These results were confirmed by ELISA-type binding assays. It was also shown that there is no direct interaction between VPg and the other subunit of eIF4F, namely eIF4G. Finally, with the same experimental system, it was shown that the presence of eIF4G does not influence the binding affinity of VPg and eIF4E. / The interaction of VPg with the plant translation apparatus suggests that potyviral infection may alter the host protein expression profile. This hypothesis was investigated with the use of a protoplast system. We have shown that the global rates of protein synthesis in protoplasts transfected with an infectious TuMV cDNA clone dropped shortly after transfection, by as much as an estimated 70%. Recovery to normal levels occurred within 48 hours. / Evidence was obtained that the interaction between VPg and eIF4E is instrumental in this transient down-regulation of protein expression: protoplasts transfected with a mutant TuMV cDNA clone, the VPg of which has no affinity for eIF4E, failed to exhibit the drop in protein synthesis observed with the wild-type clone.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37812 |
| Date | January 2000 |
| Creators | Plante, Daniel, 1970- |
| Contributors | Fortin, Marc G. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Plant Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001808169, proquestno: NQ70128, Theses scanned by UMI/ProQuest. |
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