Microscale Thermophoresis for Thermodynamic Analysis: A Proof-of-Concept Study on LIMK Inhibitors.

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Limb kinase 1 (LIMK1) and LIMK2 regulate cytoskeleton dynamics, crucial for cell function.
• These kinases are challenging to produce and purify for traditional biochemical analysis.
• LIMK1 and LIMK2 are potential therapeutic targets due to their roles in actin and microtubule remodeling.

Purpose of the Study:

• To develop a purification-free method for studying LIMK-inhibitor interactions.
• To validate microscale thermophoresis (MST) as a platform for thermodynamic analysis of protein-ligand binding in cell lysates.
• To assess the binding thermodynamics of LIMK1 and LIMK2 with specific inhibitors.

Main Methods:

• Overexpression of fluorescent miRFP670-LIMK fusion proteins in HEK293 cells.
• Application of microscale thermophoresis (MST) to measure binding directly in cell lysates.
• Determination of dissociation constants (K_d) across various temperatures and van't Hoff analysis.

Main Results:

• MST successfully measured LIMK-inhibitor interactions without protein purification.
• LIMK1 and its kinase domain (Kin1) exhibited similar binding affinities to TH-257 and LX7101.
• LIMK2 displayed significantly weaker binding interactions compared to LIMK1.
• Binding was found to be enthalpy-driven, indicating potential for inhibitor optimization.

Conclusions:

• Microscale thermophoresis provides a user-friendly, purification-free platform for studying protein-ligand thermodynamics.
• This approach is effective for analyzing challenging targets directly within cell lysates.
• The findings support MST as a versatile tool for guiding the development of therapeutic inhibitors targeting LIMK proteins.