Journal
EMBO JOURNAL
Volume 28, Issue 20, Pages 3171-3184Publisher
WILEY
DOI: 10.1038/emboj.2009.256
Keywords
Cauliflower mosaic virus (CaMV); eIF3; large ribosomal subunit (60S); re-initiation supporting protein (RISP); transactivator viroplasmin (TAV)
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Funding
- Fonds National de la Science (ACI, France) [BCMS364]
- Agence Nationale de la Recherche (France) [BLAN06-2_135889]
- Fondation pour la Recherche Medicale (France) [INE 20031114123]
- Ministry of Research
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The plant viral re-initiation factor transactivator viroplasmin (TAV) activates translation of polycistronic mRNA by a re-initiation mechanism involving translation initiation factor 3 (eIF3) and the 60S ribosomal subunit (60S). QJ; Here, we report a new plant factor-re-initiation supporting protein (RISP)-that enhances TAV function in re-initiation. RISP interacts physically with TAV in vitro and in vivo. Mutants defective in interaction are less active, or inactive, in transactivation and viral amplification. RISP alone can serve as a scaffold protein, which is able to interact with eIF3 subunits a/c and 60S, apparently through the C-terminus of ribosomal protein L24. RISP pre-bound to eIF3 binds 40S, suggesting that RISP enters the translational machinery at the 43S formation step. RISP, TAV and 60S co-localize in epidermal cells of infected plants, and eIF3-TAV-RISP-L24 complex formation can be shown in vitro. These results suggest that RISP and TAV bridge interactions between eIF3-bound 40S and L24 of 60S after translation termination to ensure 60S recruitment during repetitive initiation events on polycistronic mRNA; RISP can thus be considered as a new component of the cell translation machinery. The EMBO Journal (2009) 28, 3171-3184. doi:10.1038/emboj.2009.256; Published online 10 September 2009
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