Free calcium transients in chemotactic and non-chemotactic strains of Escherichia coli determined by using recombinant aequorin

Watkins, N. J., Knight, M. R., Trewavas, A. J. and Campbell, Anthony Keith 1995. Free calcium transients in chemotactic and non-chemotactic strains of Escherichia coli determined by using recombinant aequorin. Biochemical Journal 306 , pp. 865-869.

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Abstract

Intracellular Ca2+ has been previously implicated in the chemotactic response of Escherichia coli. However, no correlative measurements of intracellular free Ca2+ have been made during bacterial chemotaxis, essential if this is to be established. In order to monitor internal free Ca2+ in E. coli during challenge with chemotactic agents, the Ca(2+)-activated photoprotein aequorin was expressed in a chemotactic strain (AB1157) and a non-chemotactic strain [BL21(DE3)] of E. coli. Repellents were found to cause an increase (50-150 nM) in intracellular free Ca2+, whereas attractants caused a small but consistent decrease in intracellular free Ca2+. These data are in agreement with the proposed model that an increase in intracellular free Ca2+ causes tumbling. The effect of increasing external Ca2+ on the regulation of intracellular free Ca2+ in both strains was monitored by using aequorin. The resting level of free Ca2+ in E. coli (AB1157) was found to be 100 nM, which agrees with previous data [Gangola and Rosen (1987) J. Biol. Chem. 262, 12570-12574]. As these results also show differences in the regulation of intracellular free Ca2+ between the two strains in the presence of high external Ca2+ concentrations, this may have implications for the effect of high-Ca2+ environments on E. coli.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine Pharmacy
Subjects:	Q Science > QD Chemistry Q Science > QR Microbiology R Medicine > RM Therapeutics. Pharmacology
Publisher:	Biochemical Society
ISSN:	0264-6021
Last Modified:	05 Jun 2017 02:58
URI:	https://orca.cardiff.ac.uk/id/eprint/22495

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