Dissociating activity of purified colicin E 2 on the isolated DNA-membrane complex of Escherichia coli

Abstract

1. Experiments were performed to observe the biochemical action of colicin E 2 in the subcellular system, and purified colicin E 2 was found to release DNA from the isolated DNA-membrane complex of Escherichia coli in the presence of ATP. 5 to 10 μg/ml of colicin E 2 was sufficient to induce 50 % release. 2. No DNA degradation was observed during the release of DNA from the membrane complex by colicin E 2. 3. The reaction was highly dependent on temperature and no reaction occurred below the critical temperature of 20°C. 4. ATP could be replaced by several nucleotide triphosphates, ADP and inorganic pyrophosphate. 5. No resistant and tolerant mutants to colicin E 2 had been found whose DNA-membrane complexes showed resistance to the reaction of colicin E 2 in vitro. 6. Purified colicin E 3 and K proteins did not release DNA from the complex, suggesting the presence of a highly specific interaction between colicin E 2 protein and the membrane complex.