The CNK-HYP scaffolding complex promotes RAF activation by enhancing KSR-MEK interaction

Area of Science:

• Molecular Biology
• Cell Signaling
• Biochemistry

Background:

• The RAS-MAPK pathway is vital for cell functions like proliferation and survival.
• Dysregulation of this pathway is linked to cancer development.
• RAF activation by RAS is complex and not fully understood, involving RAF dimerization.

Purpose of the Study:

• To investigate the role of fly scaffold proteins CNK and HYP in RAF activation.
• To elucidate the structural mechanisms underlying KSR-MEK-CNK-HYP complex formation.
• To understand how these components regulate RAF-KSR heterodimerization and activation.

Main Methods:

• Utilized cryogenic electron microscopy (cryo-EM) to determine the structure of the KSR-MEK-CNK-HYP complex.
• Investigated the stabilization of KSR-MEK interactions by CNK and HYP.
• Analyzed the impact on RAF-KSR heterodimerization and subsequent RAF activation.

Main Results:

• CNK and HYP stabilize the KSR-MEK interaction.
• This stabilization enhances RAF-KSR heterodimerization, leading to increased RAF activation.
• Cryo-EM revealed a ring-like structure of CNK-HYP engaging both KSR and MEK simultaneously.

Conclusions:

• CNK and HYP play a critical role in RAF activation by stabilizing the KSR-MEK complex.
• The findings highlight the importance of scaffold proteins in regulating RAF allosteric function and dimerization.
• This work sheds light on diverse mechanisms controlling RAF activation and the regulatory potential of KSR-MEK interactions.