Engineering an Osmosensor by Pivotal Histidine Positioning within Disordered Helices.

ABSTRACT: Histidine kinases (HKs) funnel diverse environmental stimuli into a single autophosphorylation event at a conserved histidine residue. The HK EnvZ is a global sensor of osmolality and cellular acid pH. In previous studies, we discovered that osmosensing in EnvZ was mediated through osmolyte-induced stabilization of the partially disordered helical backbone spanning the conserved histidine autophosphorylation site (His²⁴³). Here, we describe how backbone stabilization leads to changes in the microenvironment of His²⁴³, resulting in enhanced autophosphorylation through relief of inhibition and repositioning of critical side chains and imidazole rotamerization. The conserved His-Asp/Glu dyad within the partially structured helix is equally geared to respond to acid pH, a

SUBMITTER: Ghosh M 

PROVIDER: S-EPMC6377431 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature