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Translational control of poly(A)-binding protein expression

J Bag1, J Wu

  • 1Department of Molecular Biology and Genetics, University of Guelph, Canada.

European Journal of Biochemistry
|April 1, 1996
PubMed

Insights

Poly(A)-binding protein (PABP) represses its own mRNA translation. Removing PABP binding sites from the 5' UTR enhances translation, indicating a negative feedback mechanism for PABP regulation.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • Protein Synthesis

Background:

  • Poly(A)-binding protein (PABP) is crucial for eukaryotic mRNA translation and poly(A) tail metabolism.
  • PABP mRNA exhibits inefficient translation in many eukaryotic cells.
  • The 5' untranslated region (UTR) of PABP mRNA contains adenine-rich sequences potentially involved in autoregulation.

Purpose of the Study:

  • To investigate the role of the 5' UTR of PABP mRNA in regulating its own translation.
  • To determine if PABP directly binds to its mRNA's 5' UTR to control translation.
  • To elucidate the mechanism of PABP autoregulation.

Main Methods:

  • In vitro transcription of full-length and truncated PABP mRNA.
  • Cell-free translation assays using rabbit reticulocyte lysate.
  • UV-mediated cross-linking to study RNA-protein interactions.
  • Centrifugation to separate polysomal and free mRNA-protein complexes.

Main Results:

  • Deletion of putative PABP-binding sites in the 5' UTR enhanced mRNA translation.
  • Exogenous PABP inhibited translation of full-length PABP mRNA but not truncated mRNA.
  • PABP directly binds to the 5' UTR of its mRNA, particularly within the first 223 nucleotides.
  • PABP preferentially associates with non-translated free mRNA, not polysomes.

Conclusions:

  • PABP autoregulates its translation through a negative feedback mechanism.
  • Binding of PABP to its 5' UTR represses translation.
  • This autoregulation involves PABP binding to adenine-rich regions within the 5' UTR, sequestering the mRNA from translation.

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