Figure 1: Design and activity of HK853 and EnvZ chimeras.

(a) Observation of the differential DHp connector handedness between EnvZ and HK853. Cartoon representation in cylindrical helices for the DHp superimposition of homodimeric HK853 (2C2A; one subunit in pink and the other (*) in purple) and EnvZ (3ZRW; one subunit in yellow and the other (*) in orange). A view of the independently superimposed structures rotated 90° is in the right side. In this view, the CA domain has been drawn connected to the α2 helices. The helices in the homodimers are labelled and phosphorylatable His is shown as sticks. (b) The DHp sequence from EnvZ, HK853 and the generated chimeras, EnvZ^chim and HK853^chim are aligned and the DHp region interchanged to form chimeras is highlighted in grey. The phosphorylatable His is highlighted in blue and the acidic residue after the His is highlighted in red. Residues involved in RR recognition and binding in the HK853–RR468 complex are highlighted⁷ in magenta and residues involved in rewiring phosphotransfer for EnvZ²⁷ are highlighted in yellow. (c) Autophosphorylation assays of HK853, HK853^chim, EnvZ and EnvZ^chim. The HKs were incubated with [γ³²]ATP for 1, 2.5, 5, 7.5, 10, 15 and 30 min at 37 °C. The phosphorylated proteins were visualized by autoradiography.