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Ubiquitin-mediated mRNP dynamics and surveillance prior to budding yeast mRNA export

Nahid Iglesias1, Evelina Tutucci, Carole Gwizdek

  • 1Department of Cell Biology, Sciences III, 1211 Geneva 4, Switzerland. Nahid.Iglesias@epfl.ch

Genes & Development
|September 3, 2010
PubMed

Insights

The mRNA export receptor Mex67/NXF1 utilizes Nab2 as an alternative adaptor, with Yra1/REF acting as a stabilizing cofactor. This pathway is crucial for nuclear export and involves surveillance mechanisms.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • The mRNA export receptor Mex67/NXF1 facilitates mRNA-ribonucleoprotein (mRNP) complex export through nuclear pores.
  • Yra1/REF is a known adaptor for Mex67/NXF1, but its dispensability in certain organisms suggests alternative adaptors exist.

Purpose of the Study:

  • To identify alternative adaptors for the mRNA export receptor Mex67/NXF1.
  • To elucidate the role of Nab2 and Yra1/REF in mRNA export pathways.

Main Methods:

  • Co-immunoprecipitation assays to study protein interactions.
  • Analysis of mRNA export in yeast mutants with altered expression of export factors.
  • Investigating the role of ubiquitination in regulating protein-protein interactions during mRNA export.

Main Results:

  • Mex67/NXF1 directly interacts with the essential mRNA-binding protein Nab2, identifying Nab2 as a potential Mex67/NXF1 adaptor.
  • Yra1/REF enhances the Nab2-Mex67 interaction and becomes dispensable when Nab2 or Mex67 are overexpressed.
  • Ubiquitination of Yra1 by the E3 ligase Tom1 promotes its dissociation from mRNPs, and loss of Mlp proteins suppresses growth defects associated with Yra1 ubiquitination mutants.

Conclusions:

  • Nab2 functions as a key adaptor for Mex67/NXF1-mediated mRNA export.
  • Yra1/REF acts as a cofactor that stabilizes the adaptor-receptor interaction, and its dissociation is regulated by ubiquitination.
  • Tom1-mediated Yra1 dissociation is part of a nuclear pore surveillance mechanism ensuring the export of mature mRNPs.

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