Extended Data Fig. 4: Additional in vitro characterizations of selected PhoQ*–PhoP* pairs.

a, Phosphotransfer reactions for PhoQ*–PhoP* variants, as well as PhoQ* with wild-type PhoP (middle) and wild-type PhoQ with PhoP* (right). These experiments were repeated independently twice with similar results. b, Quantification of phosphatase activity for PhoQ₁*,PhoQ₅*,PhoQ₁₂* and PhoQ₁₄*, as in Fig. 2c. Lines indicate mean ± s.d. from n = 3 biological replicates. c, Phosphotransfer profiles of wild-type PhoQ (top) and three PhoQ* variants, as in Fig. 2d, but for 60 min and 5 min instead of just 5 min. In each case, the kinase was autophosphorylated and then incubated for 5 or 60 min individually with each of 27 response regulators from E. coli, and its selected PhoP* variant, followed by SDS–PAGE and autoradiography. The position of the autophosphorylated kinase and the approximate positions of any phosphorylated regulators are indicated by arrowheads on the left. These experiments were repeated independently twice with similar results.