Structural Basis of TPR-Mediated Oligomerization and Activation of Oncogenic Fusion Kinases

Area of Science:

• Molecular Biology
• Structural Biology
• Oncology

Background:

• The TPR protein is a component of the nuclear pore complex.
• TPR is implicated in at least five oncogenic fusion kinases, including TPR-MET.
• The mechanism by which TPR fusions activate kinases and oncogenic activities is not well understood.

Purpose of the Study:

• To elucidate the structural basis of TPR-MET oncogenic activity.
• To understand how TPR fusions contribute to kinase activation.

Main Methods:

• Crystal structure determination of TPR(2-142).
• Analysis of TPR(2-142) coiled-coil dynamics using mutagenesis.
• Assessing the effect of TPR(2-142) fusion on MET kinase domain structure and activity.

Main Results:

• The crystal structure of TPR(2-142) reveals a continuous alpha helix forming an antiparallel tetramer via leucine zippers.
• TPR coiled-coil structure is highly dynamic, with single mutations altering conformation.
• Fusion of TPR(2-142) to MET selectively stabilizes the MET kinase domain's alphaG helix.
• Mutations in TPR leucine zipper residues at the TPR-MET junction abolish kinase activation.

Conclusions:

• The TPR subunit's structure and dynamic coiled-coil are critical for oncogenic fusion kinase activation.
• TPR fusion stabilizes the MET kinase domain, promoting dimerization and activation.
• This study provides structural insights into TPR's role in oncogenesis.