Related Experiment Video
Updated: May 18, 2026
Computational Prediction of Amino Acid Preferences of Potentially Multispecific Peptide-Binding Domains Involved in Protein-Protein Interactions
Published on: January 26, 2024
Characterization of molecular determinants of the conformational stability of macrophage migration inhibitory factor:
Farah El-Turk1, Bruno Fauvet, Amer Ashrafi
1Laboratory of Molecular and Chemical Biology of Neurodegeneration, Department of Life Sciences, Swiss Federal Institute of Technology, Lausanne, Switzerland.
Abstract:
Macrophage Migration Inhibitory Factor (MIF) is a key mediator of inflammatory responses and innate immunity and has been implicated in the pathogenesis of several inflammatory and autoimmune diseases. The oligomerization of MIF, more specifically trimer formation, is essential for its keto-enol tautomerase activity and probably mediates several of its interactions and biological activities, including its binding to its receptor CD74 and activation of certain signaling pathways. Therefore, understanding the molecular factors governing the oligomerization of MIF and the role of quaternary structure in modulating its structural stability and multifunctional properties is crucial for understanding the function of MIF in health and disease. Herein, we describe highly conserved intersubunit interactions involving the hydrophobic packing of the side chain of Leu46 onto the β-strand β3 of one monomer within a hydrophobic pocket from the adjacent monomer constituted by residues Arg11, Val14, Phe18, Leu19, Val39, His40, Val41, Val42, and Pro43. To elucidate the structural significance of these intersubunit interactions and their relative contribution to MIF's trimerization, structural stability and catalytic activity, we generated three point mutations where Leu46 was replaced by glycine (L46G), alanine (L46A) and phenylalanine (L46F), and their structural properties, stability, oligomerization state, and catalytic activity were characterized using a battery of biophysical methods and X-ray crystallography. Our findings provide new insights into the role of the Leu46 hydrophobic pocket in stabilizing the conformational state of MIF in solution. Disrupting the Leu46 hydrophobic interaction perturbs the secondary and tertiary structure of the protein but has no effect on its oligomerization state.
Insights
Macrophage Migration Inhibitory Factor (MIF) oligomerization is vital for its function. Disrupting the Leu46 hydrophobic interaction affects MIF
Area of Science:
- Biochemistry
- Structural Biology
- Immunology
Background:
- Macrophage Migration Inhibitory Factor (MIF) is crucial in inflammation and immunity.
- MIF oligomerization, particularly trimer formation, is essential for its enzymatic activity and receptor binding.
- Understanding MIF's quaternary structure is key to its role in inflammatory and autoimmune diseases.
Purpose of the Study:
- Investigate the role of specific intersubunit interactions in MIF oligomerization and stability.
- Elucidate the contribution of the Leu46 hydrophobic pocket to MIF's structural integrity and function.
- Characterize the effects of disrupting Leu46 interactions on MIF's structure, stability, and catalytic activity.
Main Methods:
- Site-directed mutagenesis to create Leu46 point mutations (L46G, L46A, L46F).
- Biophysical techniques (e.g., spectroscopy, calorimetry) to assess protein stability and structure.
- X-ray crystallography to determine the structural impact of mutations.
- Enzyme kinetics assays to evaluate catalytic activity.
Main Results:
- Identified a conserved hydrophobic interaction involving Leu46 critical for stabilizing MIF's structure.
- Mutations at Leu46 perturbed secondary and tertiary protein structure.
- Disruption of the Leu46 interaction did not affect MIF's oligomerization state or trimer formation.
- Catalytic activity of MIF was not significantly altered by the L46 mutations.
Conclusions:
- The Leu46 hydrophobic interaction is important for maintaining MIF's conformational stability in solution.
- MIF's oligomerization and catalytic activity are largely independent of the Leu46-mediated hydrophobic interactions.
- These findings offer insights into MIF structure-function relationships relevant to inflammatory diseases.
