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  • The EMBO Journal (2004) 23, 1381 - 1391
  • doi:10.1038/sj.emboj.7600140

Published online: 26 February 2004

Eucaryotic initiation factor 4B controls eIF3-mediated ribosomal entry of viral reinitiation factor

Hyun-Sook Park1,a, Karen S Browning2, Thomas Hohn1 and Lyubov A Ryabova1

  1. Friedrich Miescher-Institute, Basel, Switzerland
  2. Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA

Correspondence to:

Thomas Hohn, Present address: T Hohn, Botany Department, Plant Health Unit, Basel University, CH-4056 Basel, Schönbeinstr. 6, Switzerland. Tel.: +41 61 267 29 77; E-mail: hohn@fmi.ch

Lyubov A Ryabova, LA Ryabova, Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg Cedex, France. E-mail: lyuba.ryabova@ibmp-ulp.u-strasbg.fr

aPresent address: Botany Department, Plant Health Unit, Basel University, CH-4056 Basel, Schönbeinstr. 6, Switzerland

Received 1 October 2003; Accepted 2 February 2004

The cauliflower mosaic virus reinitiation factor TAV interacts with host translation initiation factor 3 (eIF3) and the 60S ribosomal subunit to accomplish translation of polycistronic mRNAs. Interaction between TAV and eIF3g is critical for the reinitiation process. Here, we show that eIF4B can preclude formation of the TAV/eIF3 complex via competition with TAV for eIF3g binding; indeed, the eIF4B- and TAV-binding sites on eIF3g overlap. Our data indicate that eIF4B interferes with TAV/eIF3/40S ribosome complex formation during the first initiation event. Consequently, overexpression of TAV in plant protoplasts affects only second initiation events. Transient overexpression of eIF4B in plant protoplasts specifically inhibits TAV-mediated reinitiation of a second ORF. These data suggest that TAV enters the host translation machinery at the eIF4B removal step to stabilize eIF3 on the translating ribosome, thereby allowing translation of polycistronic viral RNA.

  • Keywords:

    • caulimovirus,
    • initiation,
    • ribosome,
    • translation reinitiation,
    • translational transactivator (TAV)