The sensor kinase KdpD of Escherichia coli senses external K

Autor(en): Laermann, Vera
Cudic, Emina
Kipschull, Kerstin
Zimmann, Petra
Altendorf, Karlheinz 
Stichwörter: ATPASE; Biochemistry & Molecular Biology; CATION-TRANSPORT; DOMAIN; EXTENSION; Microbiology; OPERON EXPRESSION; PH; POTASSIUM-TRANSPORT; PROTEIN; SYSTEM; TURGOR
Erscheinungsdatum: 2013
Herausgeber: WILEY
Journal: MOLECULAR MICROBIOLOGY
Volumen: 88
Ausgabe: 6
Startseite: 1194
Seitenende: 1204
Zusammenfassung: 
The Kdp system of Escherichia coli is composed of the high-affinity K+ transporter KdpFABC and the two regulatory proteins KdpD (sensor kinase) and KdpE (response regulator), which constitute a typical two-component system. The kdpFABC operon is induced under K+-limiting conditions and, to a lesser extent, under high osmolality in the medium. In search for the stimulus sensed by KdpD, we studied the inhibitory effect of extracellular K+ on the Kdp system at pH6.0, which is masked by unspecific K+ transport at higher pH values. Based on KdpD derivatives carrying single aspartate replacements in the periplasmic loops which are part of the input domain, we concluded that the inhibition of the Kdp system at extracellular K+ concentrations above 5mM is mediated via KdpD/KdpE and not due to inhibition of the K+-transporting KdpFABC complex. Furthermore, time-course analyses of kdpFABC expression revealed that a decline in the extracellular K+ concentration efficiently stimulates KdpD/KdpE-mediated signal transduction. In this report we provide evidence that the extracellular K+ concentration serves as one of the stimuli sensed by KdpD.
ISSN: 0950382X
DOI: 10.1111/mmi.12251

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