Conformation-Driven Phase Separation in the Linker Domain of Focal Adhesion Kinases

Area of Science:

• Biochemistry
• Structural Biology
• Cell Biology

Background:

• Protein tyrosine kinases, specifically Pyk2 and Fak1, are key regulators of cellular processes.
• The linker regions (FAK KFL) of these kinases are implicated in protein interactions and signaling.
• Previous studies suggest Pyk2 KFL interacts with calmodulin, hinting at functional roles.

Purpose of the Study:

• To characterize the conformational properties of FAK KFL domains from Pyk2 and Fak1.
• To elucidate the structural basis of FAK KFL interactions and their potential role in protein clustering.
• To investigate the in vitro behavior of FAK KFL segments under crowding conditions.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy was used to determine chemical shift assignments and conformational properties.
• Structural modeling was employed to analyze the formation of homodimeric interfaces.
• In vitro experiments assessed the formation of condensates under high crowding conditions.

Main Results:

• FAK KFL domains exhibit predominantly disordered conformations with segments tending to form alpha-helices.
• These alpha-helical segments were modeled to form homodimeric interfaces.
• FAK KFL segments were observed to form liquid-like condensates in vitro under crowded conditions.

Conclusions:

• The study provides structural insights into the conformational dynamics of FAK KFL domains.
• Disordered protein segments within the focal adhesion complex can undergo phase separation, leading to protein clustering.
• These findings suggest a novel mechanism for regulating focal adhesion complex organization and signaling.