Mg²⁺ coordinating dynamics in Mg:ATP fueled motor proteins

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Motor proteins utilize adenosine triphosphate (ATP) for energy transduction.
• The precise coordination of magnesium ions (Mg2+) with ATP is crucial for motor protein function but not fully understood.

Purpose of the Study:

• To investigate the coordination structures of Mg2+ with the triphosphate group of ATP in various motor proteins.
• To characterize the stability and energetics of different Mg2+-ATP coordination states.

Main Methods:

• Data mining of crystal structures of motor proteins (actin, myosin, polymerases, helicase, F1-ATPase).
• Molecular dynamics simulations to further analyze coordination states.
• Structural analysis including radial distribution functions, coordination numbers, and pair interaction energy calculations.

Main Results:

• Identified diverse transitory and stable coordination arrangements between Mg2+ and ATP.
• The two most stable states involve Mg2+ coordinating two or three oxygen atoms of the ATP triphosphate group.
• Observed five-site coordination involving water molecules and the triphosphate group.
• Calculated pair interaction energies for stable states at approximately -2750 kJ/mol and -3500 kJ/mol.
• Reported the influence of water molecules in the Mg2+ hydration shell.

Conclusions:

• Mg2+-ATP coordination in motor proteins is highly variable, with specific stable configurations identified.
• Water molecules play a significant role in the coordination shell of Mg2+.
• Understanding these coordination states provides insights into the mechanism of ATP hydrolysis in motor proteins.