Cytoplasmic free-Ca2+ levels in Escherichia coli were measured by use of the fluorescent Ca(2+)-indicator dye fura-2. Chemotactically wild-type E. coli regulated cytoplasmic free Ca2+ at approximately 100 nM when no stimuli were encountered, but changes in bacterial behavior correlated with changes in cytoplasmic free-Ca2+ concentration. For chemotactically wild-type E. coli, addition of a repellent resulted in cells tumbling and a transient increase in cytoplasmic free-Ca2+ levels. Conversely, addition of an attractant to wild-type cells caused running and produced a transient decrease in cytoplasmic free-Ca2+ levels. Studies with mutant strains showed that the chemoreceptors were required for the observed changes in cytoplasmic free-Ca2+ levels in response to chemical stimuli.
Proceedings of the National Academy of Sciences
National Academy of Sciences
Digital Object Identifier (DOI)
Tisa, L.S. and J. Adler. 1995. Cytoplasmic free-Ca+2 level rises with repellents and falls with attractants in Escherichia coli chemotaxis. Proc. Natl. Acad. Sci. USA 92:10777-10871. (DOI: 10.1073/pnas.92.23.10777)