Activation of Bacterial Histidine Kinases: Insights into the Kinetics of the cis Autophosphorylation Mechanism

Abstract

Two-component systems consisting of an input-sensing histidine kinase (HK) and an output-generating response regulator (RR) are one of the key apparatuses utilized by bacteria for adapting to the extracellular milieu. HK autophosphorylation is shown to occur primarily in trans (intermolecular) and more recently shown to occur in cis (intramolecular). Although the catalysis of HK activation remains universal, the reaction scheme for evaluation of the kinetic parameter differs between these designs and cis mode largely remains unexplored. We combined experimental and theoretical approach to unravel two-step mechanism of activation of three cis mode HKs of M. tuberculosis . The new mathematical model yields best-fit parameters to estimate the rates of HK-ATP association and HK autophosphorylation.