Modeling the Regulation of the Activity of Glutamine Synthetase from Escherichia coli by Magnesium Ions

Abstract

This work presents computer modeling of the activity of glutamine synthetase, which is a key component of nitrogen metabolism that catalyzes the synthesis of glutamine from glutamate and ammonia in an ATP-depending reaction. An algorithm based on the stochastic approach was applied to simulate the processes of substrate binding and activation. An evaluation of the effects of free Mg²⁺ ions on the activity of glutamine synthetase was performed and the optimal activation mechanism was determined. The major conclusion is that activation of bacterial glutamine synthetase in vivo is due to a consecutive mechanism with sequential Mg²⁺ ions binding first to the substrate-free form.