Metallo-enzymes Released from Escherichia coli by Osmotic Shock

Escherichia coli grown in the presence of ethylenediaminetetraacetate revealed a selective depression in the levels of cyclic phosphodiesterase, 5'-nucleotidase, and alkaline phosphatase.This was not due to the formation of an inhibitor.The reduction was most striking when the concentration of EDTA was sufficient to cause a small impairment of growth.However, substantial reduction in enzyme activity could also be demonstrated in the presence of excess MgC12; under such conditions growthwasnormal.Six other enzymes were unaffected by exposure to the chelating agent, and the patterns of ribosomal RNA were normal.Cells grown in the presence of EDTA were abnormally sensitive to actinomycin D and showed reduced uptake of 3H-uracil into acid-insoluble products.Experiments with purified, W-labeled EDTA indicated that the cells did not take up this material.It is suggested that EDTA acts by binding a trace metal ion essential for the activity of cyclic phosphodiesterase, 5'-nucleotidase, and alkaline phosphatase.