Analysis of the intracellular DNA-protein associations inEscherichia coli andBacillus subtilis

Intracellular DNA-protein complexes free of RNA have been isolated fromEscherichia coli B andBacillus subtilis 168. The complexes were characterized by the protein/DNA ratio (approximately 0.4) and by physico-chemical parameters. Using electrophoretic methods, it was shown that the protein component of the studied complexes from both microorganisms contained acid and basic proteins. The composition of the protein component of complex isolated fromBacillus subtilis was studied with respect to the growth rate of the culture. It was found that the sample from a slowly growing culture contained always higher amounts of basic proteins with a lower electrophoretic mobility than that from a culture growing more rapidly. A possible role of these proteins is discussed.