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Title

Dynamics of an interactive network composed of a bacterial two-component system, a transporter and K+ as mediator

AuthorsHeermann, Ralf; Zigann, Katja; Rodríguez Fernández, María; Banga, Julio R. ; Kremling, Andreas; Jung, Kirsten
Issue Date2014
PublisherPublic Library of Science
CitationPLoS ONE 9(2): e89671 (2014)
AbstractKdpD and KdpE form a histidine kinase/response regulator system that senses K+ limitation and induces the kdpFABC operon, which encodes a high-affinity K+ uptake complex. To define the primary stimulus perceived by KdpD we focused in this study on the dynamics of the Kdp response. Escherichia coli cells were subjected to severe K+ limitation, and all relevant parameters of the Kdp response, i.e., levels of kdpFABC transcripts and KdpFABC proteins, as well as extra- and intracellular K+ concentrations, were quantitatively analysed over time (0 to 180 min). Unexpectedly, induction of kdpFABC was found to follow a non-monotonic time-course. To interpret this unusual behaviour, a mathematical model that adequately captures the dynamics of the Kdp system was established and used for simulations. We found a strong correlation between KdpD/KdpE activation and the intracellular K+ concentration, which is influenced by the uptake of K+ via the KdpFABC complex. Based on these results a model is proposed in which KdpD/KdpE phosphorylation is inversely correlated with the intracellular K+ concentration. To corroborate this hypothesis an isogenic mutant that produces a defective KdpFABC complex, and the trans-complemented mutant that expresses the KtrAB high-affinity K+ uptake system of Vibrio alginolyticus were quantitatively analysed. Experimental data and simulations for the mutants consistently support the tight correlation between KdpD/KdpE activation and the intracellular K+ concentration. This study presents a striking example of the non-intuitive dynamics of a functional unit comprising signalling proteins and a transporter with K+ as mediator
Description15 páginas, 4 figuras, 1 tabla
Publisher version (URL)http://dx.doi.org/10.1371/journal.pone.0089671
URIhttp://hdl.handle.net/10261/95154
DOI10.1371/journal.pone.0089671
ISSN1932-6203
E-ISSN1932-6203
Appears in Collections:(IIM) Artículos
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