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ATP regulates calcium efflux and growth in E. coli

Naseem, Riffat, Wann, Kenneth Taylor, Holland, I. Barry and Campbell, Anthony Keith 2009. ATP regulates calcium efflux and growth in E. coli. Journal of Molecular Biology 391 (1) , pp. 42-56. 10.1016/j.jmb.2009.05.064

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Escherichia coli regulates cytosolic free Ca2+ in the micromolar range through influx and efflux. Herein, we show for the first time that ATP is essential for Ca2+ efflux and that ATP levels also affect generation time. A transcriptome analysis identified 110 genes whose expression responded to an increase in cytosolic Ca2+ (41 elevated, 69 depressed). Of these, 3 transport proteins and 4 membrane proteins were identified as potential Ca2+ transport pathways. Expression of a further 943 genes was modified after 1 h in growth medium containing Ca2+ relative to time zero. Based on the microarray results and other predicted possible Ca2+ transporters, the level of cytosolic free Ca2+ was measured in selected mutants from the Keio knockout collection using intracellular aequorin. In this way, we identified a knockout of atpD, coding for a component of the FoF1 ATPase, as defective in Ca2+ efflux. Seven other putative Ca2+ transport proteins exhibited normal Ca2+ handling. The defect in the ΔatpD knockout cells could be explained by a 70% reduction in ATP. One millimolar glucose or 1 mM methylglyoxal raised ATP in the ΔatpD knockout cells to that of the wild type and restored Ca2+ efflux. One millimolar 2,4-dinitrophenol lowered the ATP in wild type to that in the ΔatpD cells. Under these conditions, a similar defect in Ca2+ efflux in wild type was observed in ΔatpD cells. Ten millimolar concentration of Ca2+ resulted in a 30% elevation in ATP in wild type and was accompanied by a 10% reduction in generation time under these conditions. Knockouts of pitB, a potential Ca2+ transporter, atoA, the β subunit of acetate CoA-transferase likely to be involved in polyhydroxybutyrate synthesis, and ppk, encoding polyphosphate kinase, all indicated no defect in Ca2+ efflux. We therefore propose that ATP is most likely to regulate Ca2+ efflux in E. coli through an ATPase.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Subjects: R Medicine > R Medicine (General)
R Medicine > RM Therapeutics. Pharmacology
Uncontrolled Keywords: methylglyoxal ; aequorin ; ATPase ; Keio ; transcriptome
Publisher: Elsevier
ISSN: 0022-2836
Last Modified: 05 Jun 2017 02:12

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