Details

Autor(en) / Beteiligte

• Rosenfeld, Lior
• Shirian, Jason
• Zur, Yuval
• Levaot, Noam
• Shifman, Julia M.
• Papo, Niv

Titel

Combinatorial and Computational Approaches to Identify Interactions of Macrophage Colony-stimulating Factor (M-CSF) and Its Receptor c-FMS

Ist Teil von

• The Journal of biological chemistry, 2015-10, Vol.290 (43), p.26180-26193

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2015

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The molecular interactions between macrophage colony-stimulating factor (M-CSF) and the tyrosine kinase receptor c-FMS play a key role in the immune response, bone metabolism, and the development of some cancers. Because no x-ray structure is available for the human M-CSF·c-FMS complex, the binding epitope for this complex is largely unknown. Our goal was to identify the residues that are essential for binding of the human M-CSF to c-FMS. For this purpose, we used a yeast surface display (YSD) approach. We expressed a combinatorial library of monomeric M-CSF (M-CSFM) single mutants and screened this library to isolate variants with reduced affinity for c-FMS using FACS. Sequencing yielded a number of single M-CSFM variants with mutations both in the direct binding interface and distant from the binding site. In addition, we used computational modeling to map the identified mutations onto the M-CSFM structure and to classify the mutations into three groups as follows: those that significantly decrease protein stability; those that destroy favorable intermolecular interactions; and those that decrease affinity through allosteric effects. To validate the YSD and computational data, M-CSFM and three variants were produced as soluble proteins; their affinity and structure were analyzed; and very good correlations with both YSD data and computational predictions were obtained. By identifying the M-CSFM residues critical for M-CSF·c-FMS interactions, we have laid down the basis for a deeper understanding of the M-CSF·c-FMS signaling mechanism and for the development of target-specific therapeutic agents with the ability to sterically occlude the M-CSF·c-FMS binding interface. Background: Identifying residues crucial for M-CSF·c-FMS binding remains difficult. Results: Using a combination of experimental and computational methods, we identified mutations on M-CSF that reduce affinity to c-FMS. Conclusion: Affinity-reducing mutations are located both inside and outside of the binding interface. Significance: Knowledge of the critical residues will facilitate a better understanding of the M-CSF mechanism and facilitate drug design.