Calcium responsive two-dimensional molecular assembling of lipid-conjugated calmodulin

Area of Science:

• Biomolecular Engineering
• Surface Chemistry
• Biophysics

Background:

• Calmodulin (CaM) is a calcium-sensitive protein crucial for cellular signaling.
• Protein-lipid conjugates are being explored for novel biomolecular assemblies.
• The Langmuir-Blodgett (LB) method enables precise monolayer formation at interfaces.

Purpose of the Study:

• To conjugate calmodulin with a lipid for air-water interface assembly.
• To assess the calcium sensitivity and enzymatic activity of the lipid-conjugated calmodulin (LCC).
• To explore the potential of LCC in fabricating cooperative molecular assemblies.

Main Methods:

• Conjugation of calmodulin with dioctadecyldimethylammonium bromide.
• Formation of a monolayer at the air-water interface using the LB method.
• Analysis of area-pressure isotherms to determine calcium sensitivity.
• Enzymatic assay to measure phosphodiesterase (PDE) activity modulated by LCC.

Main Results:

• Lipid-conjugated calmodulin (LCC) successfully formed a monolayer at the air-water interface.
• LCC retained its calcium sensitivity, as evidenced by changes in the isotherm.
• LCC maintained its ability to modulate the activity of phosphodiesterase (PDE) in a calcium-dependent manner.

Conclusions:

• Lipid conjugation preserves calmodulin's essential calcium-binding and enzyme-modulating functions.
• LCC is a viable component for creating functional protein assemblies at interfaces.
• This approach facilitates the development of molecular assemblies with cooperative interactions.