The specific molecular mechanism of action of the ywIE protein is currently unknown. However, YwIE is believed to dephosphorylate phosphoarginine residues using a concerted, 2-step process via SN2 reactions. Step 1 involves a nucleophilic attack of Cys7 on the phosphorus atom of the phosphoric group. Then a thiophosphate intermediate is formed. In the second step, a phosphorylation-enzyme intermediate is hydrolyzed following the deprotonation of a water molecule by Asp118. Fuhrmann et al. (2016) believe that Asp118 likely promotes the reaction through the stabilization of the positive charge of the amino group via electrostatic interaction.
Sample general dephosphorylation reaction equation: