Mg²⁺ binding to coenzyme A.

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Magnesium (Mg²⁺) is essential for cellular functions as the second most abundant intracellular cation.
• Coenzyme A (CoA) is a critical cofactor in metabolism and protein modification, containing a thiol group.
• Understanding Mg²⁺-CoA interactions is vital for cellular processes.

Purpose of the Study:

• To investigate the binding stoichiometry and thermodynamics of Mg²⁺ interaction with coenzyme A (CoA).
• To elucidate the specific coordination sites of Mg²⁺ on CoA using advanced spectroscopic and computational methods.
• To explore the conformational and chemical environment changes in CoA upon Mg²⁺ binding.

Main Methods:

• Isothermal titration calorimetry (ITC) to determine binding affinity and stoichiometry.
• 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy to identify coordination sites.
• Molecular dynamics (MD) simulations and unsupervised learning to analyze conformational changes.

Main Results:

• A 1:1 binding stoichiometry between Mg²⁺ and free CoA was observed under physiological conditions.
• Mg²⁺ directly coordinates with phosphate groups of the 4-phosphopantothenate moiety and the adenosine 5' position.
• The binding is entropically driven, with solvent release contributing to the entropy gain.
• Mg²⁺ binding alters the CoA conformational landscape, affecting its chemical environment.

Conclusions:

• Mg²⁺ binding to CoA is significant under physiological conditions, influencing CoA's role in metabolism.
• The interaction involves direct coordination and indirect effects on CoA's structure and function.
• These findings provide insights into the physiological and pathological roles of Mg²⁺ and CoA interactions.