Involvement of Ca2+ and cGMP in bacterial taxis |
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Authors: | N.G. Omirbekova V.L. Gabai M.Yu. Sherman N.V. Vorobyeva A.N. Glagolev |
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Affiliation: | Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, Moscow 119899, U.S.S.R. |
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Abstract: | Abstract The level of cGMP in a suspension of Escherichia coli cells increased transiently upon the addition of chemoattractants. Ca2+ (1 mM), but not Mg2+, produced constant tumbling of cells in the presence of the ionophore A23187. The effect was observed either in stationary-state cells, or in a logarithmic culture treated with EDTA to increase permeability by A23187. Under the same conditions, Ca2+ decreased the cytoplasmic level of cGMP. In Phormidium uncinatum , rapid 45Ca2+ accumulation followed a light-dark stimulus, or the addition of tetramethylquinone (TMQ), a chemorepellent. La3+, which increases the reversal rate, also enhanced the level of cytoplasmic Ca2+, presumably by blocking the outward Ca2+ flux. In both E. coli and P. uncinatum Ca2+ inhibited methylaccepting chemotaxis protein (MCP) methylation. It is concluded that cGMP and Ca2+ are secondary messengers in taxis information-processing. |
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Keywords: | E. coli cyanobacteria Ca2+ transport taxis MCP methylation cGMP |
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