Fig. P1.

(A) A statistical analysis of over 10,000 aligned histidine kinase sequences reveals highly correlated amino acid pairs between the two catalytic histidine kinase A (HisKA) and histidine kinase-, DNA gyrase B-, and HSP90-like ATPase (HATPase_c) domains. (B) The sequence-derived contact pairs (yellow) are found to be functionally relevant in mutagenic experiments and are used to drive docking simulations along with the catalytic ATP-His contact (red) to deduce the active conformation of the histidine kinase. (C) Molecular dynamics simulations generate an active conformation (blue) with a stable interdomain interface that requires a large domain movement when compared to a known inactive conformation of the kinase (red). (D) The contact interface from the model demonstrates that all sequence-derived contacts are simultaneously accommodated (yellow dots). Additional contacts (green dots) were utilized to repair an inactive chimeric histidine kinase protein in support of this active conformation.