Interaction of S100A6 Protein with the Four-Helical Cytokines

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• S100 proteins are versatile regulators involved in numerous physiological and pathological processes.
• Specific S100 proteins, like S100P, can interact with cytokines, influencing cell signaling.
• S100P binds to approximately 71% of studied four-helical cytokines via a specific binding site.

Purpose of the Study:

• To investigate the binding capabilities of the S100A6 protein to four-helical cytokines.
• To compare the cytokine-binding profile of S100A6 with that of S100P.
• To elucidate the molecular basis for S100A6-cytokine interactions.

Main Methods:

• Surface plasmon resonance spectroscopy was used to measure the binding affinity of recombinant human S100A6 to 35 different four-helical cytokines.
• Molecular docking studies were performed to identify the cytokine-binding site on S100A6.
• Sequence identity analysis was conducted between S100A6 and S100P.

Main Results:

• S100A6 recognized 26 out of 35 (approximately 73%) four-helical cytokines tested, with affinities ranging from 0.3 nM to 12 µM.
• The binding selectivity of S100A6 for cytokines was comparable to that of S100P, with minor differences observed for interleukin-2 and oncostatin M.
• Molecular docking confirmed an S100A6 cytokine-binding site analogous to the one found in S100P.

Conclusions:

• S100A6, like S100P, possesses a broad specificity for binding four-helical cytokines.
• These findings suggest that promiscuous S100 family members may share a conserved cytokine-binding site.
• This conserved interaction mechanism highlights the potential role of S100 proteins in regulating cytokine activity during disease states characterized by excessive cytokine release.