A new plant protein interacts with eIF3 and 60S to enhance virus-activated translation re-initiation.
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.
Thiébeauld
Odon
O
Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg Cedex, France.
Schepetilnikov
Mikhail
M
Park
Hyun-Sook
HS
Geldreich
Angèle
A
Kobayashi
Kappei
K
Keller
Mario
M
Hohn
Thomas
T
Ryabova
Lyubov A
LA
D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017796:Caulimovirus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008954:Models, Biological; D016133:Polymerase Chain Reaction; D011132:Polyribosomes / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D014176:Protein Biosynthesis / Q000235:genetics / Q000502:physiology*; D054683:Ribosome Subunits, Large, Eukaryotic / Q000378:metabolism*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D039621:Eukaryotic Initiation Factor-3; D014764:Viral Proteins