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Structural basis for the recognition of a nucleoporin FG repeat by the NTF2-like domain of the TAP/p15 mRNA nuclear

S Fribourg1, I C Braun, E Izaurralde

  • 1European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117, Heidelberg, Germany

Molecular Cell
|October 5, 2001
PubMed

Insights

The TAP-p15 heterodimer, crucial for mRNA export via nuclear pore complexes (NPCs), binds to FG repeats through a unique hydrophobic pocket on TAP, facilitating transport.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Cell Biology

Background:

  • The TAP-p15 heterodimer plays a key role in messenger RNA (mRNA) export through nuclear pore complexes (NPCs).
  • Understanding the structural basis of TAP-p15 interaction with NPC components is crucial for elucidating mRNA transport mechanisms.

Purpose of the Study:

  • To structurally analyze the interaction domains of TAP and p15 within a ternary complex with a phenylalanine-glycine (FG) repeat.
  • To elucidate the mechanism by which TAP-p15 recognizes and interacts with FG repeats for mRNA export.

Main Methods:

  • X-ray crystallography was used to determine the structure of the TAP-p15 heterodimer in complex with an FG repeat.
  • Structural comparison with other transport factors, such as NTF2, was performed.

Main Results:

  • The TAP-p15 heterodimer shares structural similarity with NTF2 but is incompatible with homodimerization or Ran binding.
  • The heterodimer recognizes FG repeats via a hydrophobic pocket exclusively on TAP, not p15.
  • This FG binding site, along with a C-terminal site on TAP, synergistically mediates mRNA transport.

Conclusions:

  • The TAP-p15 heterodimer functions as a single unit to bind FG repeats, distinct from NTF2.
  • The findings reveal a specific binding mechanism for mRNA export factors to NPC components.
  • FG repeats likely bind to diverse transport factors with a conserved conformational mode.

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