Báo cáo khoa học: Interaction of the C1 complex of Complement with sulfated polysaccharide and DNA probed by single molecule fluorescence microscopy

Interaction of the C1 complex of Complement with sulfated polysaccharide and DNA probed by single molecule fluorescence microscopy

Authors: Bérangère Tissot, Régis Daniel, Christophe Place

Field: Biochemistry, Complement System, Molecular Biology

Document Summary:
This study investigates the interaction between the C1 complex of the complement system, specifically its subunit C1q, with DNA and fucoidan, a sulfated polysaccharide. Using single-molecule fluorescence microscopy and DNA molecular combing, the research aimed to identify the binding sites of these non-immune ligands on C1q. The findings indicate that the collagen-like region (CLR) of C1q is the primary binding site for DNA. Furthermore, fucoidan also binds to the CLR, and its interaction with the hinge region of CLR provides a mechanistic basis for its anticomplementary activity. The study also explored the binding of the C1 complex and its components, Clr and Cls, to DNA and fucoidan, revealing that the collagen-like region contains distinct sites for DNA and the catalytic tetramer binding. The research utilizes advanced biophysical techniques to offer insights into the molecular mechanisms of complement activation and inhibition.

Detailed Table of Contents:

• Introduction
• Materials and Methods
• Buffers
• Reagents and proteins
• Surface treatment
• DNA preparation
• Fluorescent beads preparation
• Protein labeling
• Fluid phase incubations of DNA with complement proteins
• Molecular combing
• Fluorescent microscopy
• Results
• Interaction between DNA and C1q
• Interactions between fucoidan and C1q
• Discussion
• Acknowledgements
• References