Sensory domain contraction in histidine kinase CitA triggers transmembrane signaling in the membrane-bound sensor

Abstract

Significance Histidine kinases are key players in prokaryotic environment sensing. Citrate binding to the extracytoplasmic sensing domain of histidine kinase CitA triggers a contraction of the domain, resulting in a pull on the C-terminal β-strand. By a combination of liquid- and solid-state NMR spectroscopy, structural alterations observed for the isolated domain can be confirmed in context of its native environment as part of a membrane-embedded receptor. Our results demonstrate that the mechanistic model derived from the isolated ligand-sensing domain is compatible with the sensor in a native-like membrane environment and allows transfer of the model to transmembrane signaling by this class of sensor kinases.