Formation of the stoichiometric complex of EnvZ, a histidine kinase, with its response regulator, OmpR

Takeshi Yoshida, Ling Qin, Masayori Inouye

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

EnvZ, a histidine kinase, and its cognate response regulator OmpR of Escherichia coli are responsible for adaptation to external osmotic changes by regulating the levels of the outer membrane porin proteins, OmpF and OmpC. The osmosensor, EnvZ, has dual enzymatic functions with OmpR kinase and OmpR-P phosphatase. Here, we demonstrate that the cytoplasmic kinase domain of EnvZ (EnvZc) and OmpR are able to form a 1:1 complex detected by native PAGE. This indicates that two OmpR molecules can bind to one EnvZc dimer. As this 1:1 EnvZc/OmpR complex is formed even in the presence of a large excess of EnvZc, OmpR binding to EnvZc is co-operative. The complex formation is also observed between EnvZc and phosphorylated OmpR for the phosphatase reaction. OmpR-P bound to EnvZc was readily released upon the addition of OmpR, indicating that OmpR and OmpR-P can compete for the binding to EnvZ. On the basis of these results, a model is discussed to explain how cellular OmpR-P concentrations are regulated in response to medium osmolarity.

Original languageEnglish (US)
Pages (from-to)1273-1282
Number of pages10
JournalMolecular microbiology
Volume46
Issue number5
DOIs
StatePublished - 2002

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

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