Comparisons of the reaction modes for autophosphorylation of wild-type EvgS and of the mutant of D1009A.

<p>(A) Analysis of the kinetics of autophosphorylation of the mutant D1009A. The profile of the phosphorylation ratio (%) versus the reaction times (the same profile as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132598#pone.0132598.g004" target="_blank">Fig 4B</a>) was fitted to a first-order kinetic model; the half-life time (<i>t</i>_1/2) was 10 min (<i>k</i>' = 1 × 10⁻³ s^–1). In the early stages of the reaction (≤15 min), a plot of the natural logarithm of the phosphorylation ratio (%) against the reaction time formed a straight line. (B) Two schemes (scheme 1 and 2) for the autophosphorylation of the mutant D1009A dimer, (D1009A)₂, suggested by the kinetic analysis. Scheme 1 is a model of sequential autophosphorylation reactions. Scheme 2 is a model of a flip-flop autophosphorylation reaction followed by an exchange of subunits of the (D1009A)₂ dimer. (C) Scheme for the autophosphorylation reaction of wild-type EvgS. In the presence of sufficient ATP, a cycle of phosphorylation, intramolecular phosphate transfer, dephosphorylation is repeated.