A link between dimerization and autophosphorylation of the response regulator PhoB.

Response regulator proteins within two-component signal transduction systems are activated by phosphorylation and can catalyze their own covalent phosphorylation using small molecule phosphodonors. To date, comprehensive kinetic characterization of response regulator autophosphorylation is limited to CheY, which follows a simple model of phosphodonor binding followed by phosphorylation. We characterized autophosphorylation of the response regulator PhoB, known to dimerize upon phosphorylation.

Measurement of response regulator autodephosphorylation rates spanning six orders of magnitude.

Two-component regulatory systems, comprising sensor kinase and response regulator proteins, carry out signal transduction in prokaryotic and eukaryotic microorganisms, as well as plants. Response regulators act as phosphorylation-mediated switches, turning on and off cellular responses to environmental stimuli. Self-catalyzed dephosphorylation is an important determinant of the duration of the response regulator activated state.

Protein (19)F NMR in Escherichia coli.

Although overexpression and (15)N enrichment facilitate the observation of resonances from disordered proteins in Escherichia coli, (15)N enrichment alone is insufficient for detecting most globular proteins. Here, we explain this dichotomy and overcome the problem while extending the capability of in-cell NMR by using (19)F-labeled proteins. Resonances from small (approximately 10 kDa) globular proteins containing the amino acid analogue 3-fluoro-tyrosine can be observed in cells, but for larger proteins the (19)F resonances are broadened beyond detection.