Glu-96 of basic fibroblast growth factor is essential for high affinity receptor binding. Identification by...

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Signaling

Background:

• Basic fibroblast growth factor (bFGF) plays a significant role in various pathophysiological processes.
• Developing receptor antagonists for bFGF requires understanding its functional binding epitopes.
• Characterizing bFGF-receptor interactions is crucial for therapeutic target identification.

Purpose of the Study:

• To investigate the impact of specific residue alterations on bFGF receptor binding affinity.
• To identify critical amino acid residues involved in the functional binding of bFGF to its receptor.
• To elucidate the contribution of different regions of bFGF to receptor interaction.

Main Methods:

• Site-directed mutagenesis was used to create bFGF muteins with altered residues.
• Mutated bFGF proteins were expressed in Escherichia coli and purified using heparin-Sepharose chromatography.
• Receptor binding affinities of wild-type and mutant bFGF were evaluated.

Main Results:

• Alterations at positions 107 and 109-114 of bFGF showed minimal impact on receptor binding affinity.
• Residues 109-114 of bFGF were confirmed to constitute a low-affinity binding site.
• Substitution of Glutamate-96 (Glu-96) with alanine drastically reduced binding affinity to 0.1% of wild type.
• Mutations of Glu-96 to lysine or glutamine resulted in 0.3% and 10% affinity, respectively, highlighting the need for a negative charge.

Conclusions:

• Residues 106-115 of bFGF constitute a low-affinity binding site for its receptor.
• Glutamate-96 is a critical residue essential for high-affinity binding of bFGF to fibroblast growth factor receptor-1.
• These findings provide insights into bFGF-receptor interactions, aiding in the design of targeted therapies.