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Insights into oncogenic mutations of plexin-B1 based on the solution structure of the Rho GTPase binding domain

Yufeng Tong1, Prasanta K Hota, Mehdi Bagheri Hamaneh

  • 1Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.

Structure (London, England : 1993)
|February 16, 2008
PubMed

Insights

Structural insights into plexin-B1 mutations reveal how cancer-associated changes in the Rho GTPase binding domain (RBD) affect receptor function and binding affinity. This research clarifies the molecular basis of plexin-B1

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Cancer Research

Background:

  • Plexin-B1, a transmembrane receptor, plays roles in axon guidance, angiogenesis, and cancer.
  • Somatic missense mutations in plexin-B1 have been identified in breast and prostate cancers, particularly within the Rho GTPase binding domain (RBD).

Purpose of the Study:

  • To determine the NMR solution structure of the plexin-B1 RBD.
  • To investigate the structural and functional impact of oncogenic mutations within the plexin-B1 RBD on Rho GTPase binding.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy was used to determine the 3D structure of the plexin-B1 RBD.
  • Analysis of oncogenic mutations T1795A, T1802A, L1815F, and L1815P within the RBD.

Main Results:

  • The plexin-B1 RBD exhibits a ubiquitin-like fold with specific surface features.
  • Mutations T1795A and T1802A locally perturb the structure but do not affect Rho GTPase binding affinity.
  • Mutations L1815F and L1815P, located at the Rho GTPase binding site, abolish binding affinity for Rac1 and Rnd1 by disrupting beta3-beta4 sheet conformation.

Conclusions:

  • The determined structure of the plexin-B1 RBD provides a molecular basis for understanding oncogenic mutations.
  • The study rationalizes the oncogenic behavior of plexin-B1 mutants based on their structural impact and effects on Rho GTPase binding.

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