Engineered zwitterionic phosphorylcholine monolayers for elucidating multivalent binding kinetics of C-reactive...

Area of Science:

• Biomaterials Science
• Biochemistry
• Surface Chemistry

Background:

• C-reactive protein (CRP) activation on plasma membranes is crucial for understanding inflammation and infection.
• Previous studies showed CRP binding dynamics are influenced by ionic microenvironments.
• A robust sensing platform is needed to elucidate CRP's molecular dynamics.

Purpose of the Study:

• To investigate the effect of ligand density on a surface, a key physicochemical parameter, on C-reactive protein (CRP) multivalent binding modes.
• To develop a cell membrane-mimetic surface with tunable ligand density for studying CRP binding kinetics.
• To understand how CRP undergoes conformational transitions upon binding to surfaces.

Main Methods:

• Synthesis of a phospholipid analogue with thiol ends to create self-assembled monolayers with tunable lateral ligand density.
• Measurement of CRP multivalent binding kinetics using surface plasmon resonance (SPR) on engineered surfaces.
• Utilized a monomeric CRP-specific DNA aptamer to study CRP structural transitions.

Main Results:

• On-rate and off-rate constants for CRP binding increased with ligand density, leading to stable dissociation constants.
• Optimal binding affinity in the second ligand-occupation reaction was observed as a function of ligand density.
• Pentameric CRP transitioned into monomers upon surface adsorption via multivalent contacts in a pH-dependent manner.

Conclusions:

• The study demonstrates how ligand arrangement at the molecular level alters multivalent binding reactions of CRP.
• Bioengineering approaches reveal CRP activation through conformational transitions induced by multiplex binding.
• Findings provide insights into CRP's response to inflammation and guide the development of advanced biomaterials.