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Novel RNA-Binding Proteins Isolation by the RaPID Methodology
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Determinants of Rbp1p localization in specific cytoplasmic mRNA-processing foci, P-bodies

Li-Ting Jang1, Leh-Miauh Buu, Fang-Jen S Lee

  • 1Institute of Molecular Medicine, School of Medicine, National Taiwan University and Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.

The Journal of Biological Chemistry
|August 4, 2006
PubMed

Insights

Yeast RNA-binding protein Rbp1p degrades mitochondrial porin mRNA within cytoplasmic P-bodies. Its localization to P-bodies is regulated by specific domains and oligomerization, independent of Dhh1p or Ccr4p.

Area of Science:

  • Molecular Biology
  • Yeast Genetics
  • RNA Metabolism

Background:

  • Rbp1p is a yeast RNA-binding protein that regulates mitochondrial porin mRNA levels.
  • The precise cellular location and mechanism of Rbp1p-mediated mRNA degradation were previously unknown.

Purpose of the Study:

  • To determine the intracellular localization of the Rbp1p-mediated mRNA degradation complex.
  • To elucidate the molecular determinants and regulatory factors involved in Rbp1p's P-body localization and function.

Main Methods:

  • Yeast genetics (xrn1Δ mutant strains)
  • Fluorescence microscopy for protein localization
  • Analysis of protein-protein interactions (Dhh1p)
  • mRNA localization studies

Main Results:

  • Rbp1p localizes to cytoplasmic P-bodies in xrn1Δ yeast.
  • Specific domains (N-terminal, RRM1) are necessary but not sufficient for P-body localization; C-terminal oligomerization facilitates recruitment.
  • POR1 mRNA localization to P-bodies is independent of Rbp1p.
  • Rbp1p interacts with decapping activator Dhh1p but its recruitment to P-bodies does not require Dhh1p or Ccr4p.
  • Rbp1p-mediated mRNA decay is dependent on the 5' to 3' exonuclease Xrn1p.

Conclusions:

  • Rbp1p functions within P-bodies to degrade mitochondrial porin mRNA.
  • Protein domains and oligomerization play critical roles in Rbp1p's P-body localization.
  • Xrn1p is essential for Rbp1p-mediated mRNA decay, providing insight into RNA regulation mechanisms.

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