Structural basis for the interaction between NTF2 and nucleoporin FxFG repeats.

Area of Science:

• Molecular Biology
• Structural Biology
• Cell Biology

Background:

• Nuclear transport factor 2 (NTF2) mediates the import of RanGDP, a key regulator of nucleocytoplasmic transport.
• Interactions with nucleoporins, particularly those with FxFG-repeat cores, are essential for this process.
• Understanding these interactions is crucial for comprehending nuclear trafficking mechanisms.

Purpose of the Study:

• To determine the crystal structure of yeast NTF2 bound to an FxFG-nucleoporin core.
• To elucidate the molecular basis of NTF2-nucleoporin interactions.
• To understand the role of these interactions in nuclear import and RanGDP transport.

Main Methods:

• X-ray crystallography at 1.9 A resolution.
• Site-directed mutagenesis to create NTF2 variants.
• Yeast complementation assays to assess protein function in vivo.

Main Results:

• The crystal structure revealed two identical FxFG binding sites on dimeric NTF2, formed by residues from each chain.
• Engineered mutations at the interface disrupted NTF2 binding to nuclear pores.
• Mutant NTF2 proteins caused reduced growth rates and Ran mislocalization in yeast.
• Comparison with importin-beta and TAP/p15 structures identified common binding site features.

Conclusions:

• The determined structure provides a molecular basis for NTF2-nucleoporin interactions critical for nuclear import.
• The findings explain the specificity and efficiency of nuclear pore complex (NPC) translocation.
• These insights contribute to understanding the broader principles of nucleocytoplasmic transport mediated by transport factors.