Escherichia coli is exposed to wide extracellular concentrations of Ca2+, whereas the cytosolic levels of the ion are subject to stringent control and are implicated in many physiological functions. The present study shows that extracellular Ca2+ controls cPHB [complexed poly-(R)-3-hydroxybutyrate] biosynthesis through the AtoS-AtoC two-component system. Maximal cPHB accumulation was observed at higher [Ca2+]e (extracellular Ca2+ concentration) in AtoS-AtoC-expressing E. coli compared with their ΔatoSC counterparts, in both cytosolic and membrane fractions. The reversal of EGTA-mediated down-regulation of cPHB biosynthesis by the addition of Ca2+ and Mg2+ was under the control of the AtoS-AtoC system. Moreover, the Ca2+-channel blocker verapamil reduced total and membrane-bound cPHB levels, the inhibitory effect being circumvented by Ca2+ addition only in atoSC+ bacteria. Histamine and compound 48/80 affected cPHB accumulation in a [Ca2+]e-dependent manner directed by the AtoS-AtoC system. In conclusion, these data provide evidence for the involvement of external Ca2+ on cPHB synthesis regulated by the AtoS-AtoC two-component system, thus linking Ca2+ with a signal transduction system, most probably through a transporter.
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February 2009
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Research Article|
January 16 2009
Extracellular Ca2+ transients affect poly-(R)-3-hydroxybutyrate regulation by the AtoS-AtoC system in Escherichia coli
Marina C. Theodorou;
Marina C. Theodorou
*Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
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Ekaterini Tiligada;
Ekaterini Tiligada
†Department of Pharmacology, Medical School, University of Athens, M. Asias 75, GR-11527 Athens, Greece
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Dimitrios A. Kyriakidis
Dimitrios A. Kyriakidis
1
*Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
‡National Hellenic Research Foundation, Vas. Constantinou 48, GR-11635 Athens, Greece
1To whom correspondence should be addressed (email [email protected]).
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Publisher: Portland Press Ltd
Received:
June 09 2008
Revision Received:
October 10 2008
Accepted:
October 14 2008
Accepted Manuscript online:
October 14 2008
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biochem J (2009) 417 (3): 667–672.
Article history
Received:
June 09 2008
Revision Received:
October 10 2008
Accepted:
October 14 2008
Accepted Manuscript online:
October 14 2008
Citation
Marina C. Theodorou, Ekaterini Tiligada, Dimitrios A. Kyriakidis; Extracellular Ca2+ transients affect poly-(R)-3-hydroxybutyrate regulation by the AtoS-AtoC system in Escherichia coli. Biochem J 1 February 2009; 417 (3): 667–672. doi: https://doi.org/10.1042/BJ20081169
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