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Diverse cap-binding properties of Drosophila eIF4E isoforms

Joanna Zuberek1, Krzysztof Kuchta2, Greco Hernández3

  • 1Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland.

Biochimica Et Biophysica Acta
|July 5, 2016
PubMed

Insights

Drosophila melanogaster eukaryotic initiation factor 4E (eIF4E) proteins show varied cap-binding affinities. Dm eIF4E-3 exhibits the highest affinity, while Dm eIF4E-4 displays cooperativity between eIF4G binding and cap recognition.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • Eukaryotic mRNA translation primarily relies on cap-dependent mechanisms involving the eIF4E protein.
  • Drosophila melanogaster possesses eight eIF4E proteins, with the functions of most remaining uncharacterized.

Purpose of the Study:

  • To investigate the molecular basis of cap and eIF4G peptide interactions among Drosophila melanogaster eIF4E isoforms.
  • To elucidate the functional differences in cap-binding affinities and interactions within the Dm eIF4E family.

Main Methods:

  • Homology modeling was employed to predict protein structures.
  • Fluorescence binding assays were utilized to assess cap analogue binding affinities.
  • Analysis of ternary complexes involving eIF4G peptide and eIF4E-cap analogue interactions.

Main Results:

  • Significant variations in cap analogue binding affinities were observed among Class I Dm eIF4E isoforms, with differences up to 14-fold.
  • Dm eIF4E-3 demonstrated the highest affinity for cap analogues.
  • Dm eIF4E-3 and Dm eIF4E-5 appear to bind the cap's second nucleoside through unusual stacking interactions.
  • Cooperativity between eIF4G and cap binding was exclusively observed for Dm eIF4E-4.

Conclusions:

  • The study reveals distinct molecular mechanisms governing cap recognition and eIF4G interaction among Dm eIF4E family members.
  • Dm eIF4E-3 and Dm eIF4E-5 possess unique cap-binding modes.
  • Dm eIF4E-4 is uniquely regulated by eIF4G binding in relation to cap recognition.
Keywords:
Cap analoguesFluorescence spectroscopyProtein-ligand interactionsTranslation initiationeIF4E family

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