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.
Molecular, Cellular and Biomedical Sciences
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)