Adenosine Triphosphate Article Coarse grain CpxA CpxA protein, E coli Escherichia coli Proteins Escherichia coli protein Histidine Histidine kinase Hydrogen-Ion Concentration Molecular Dynamics Simulation Phosphorylation Protein Conformation Protein Domains Protein Kinases QM/MM Two component system adenosine triphosphate autophosphorylation catalysis chemistry computer simulation enzyme activation enzyme conformation enzyme mechanism enzyme phosphorylation histidine metabolism molecular dynamics pH