RAS/Effector Interactions from Structural and Biophysical Perspective.

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• RAS proteins function as crucial molecular switches controlling numerous cellular pathways.
• RAS/effector interactions are typically transient, with dissociation constants (Kd) in the micromolar to millimolar range, facilitating dynamic signaling.
• Effector proteins, despite lacking sequence homology, bind RAS via a conserved RAS-binding domain with a ubiquitin fold.

Purpose of the Study:

• To elucidate the fundamental principles governing RAS/effector protein interactions.
• To understand how oncogenic RAS mutations alter effector binding hierarchies.
• To provide insights for the rational design of drugs targeting RAS-associated diseases.

Main Methods:

• Utilizing biophysical and structural studies, including Nuclear Magnetic Resonance (NMR).
• Analyzing the binding interface, hot-spots, and intermolecular beta-sheet formation.
• Investigating the impact of GTP-bound versus GTP-hydrolyzed states on RAS flexibility and binding.

Main Results:

• RAS/effector binding involves a conserved interface with intermolecular beta-sheet formation, hydrogen bonds, and salt bridges.
• Interactions are specific to the active, GTP-bound RAS state and are disrupted by GTP hydrolysis.
• RAS exhibits preferential binding to certain effectors, a hierarchy that can be altered in oncogenic RAS mutants.

Conclusions:

• RAS/effector interactions are governed by specific structural and biophysical principles, involving a common binding mode.
• Altered effector binding hierarchies in oncogenic RAS mutants can disrupt downstream signaling networks.
• Structural and biophysical insights into RAS/effector interactions are crucial for developing therapeutic strategies for RAS-related pathologies.