Isolation of a DNA-protein complex containing a single DNA fragment which is at or near the replication origin of the Bacillus subtilis chromosome.

A chromosomal fragment containing purA, the nearest marker from the replication origin of the Bacillus subtilis chromosome, was highly purified as a complex containing at least proteins and being solubilized easily during cell lysis. The complex had a markedly higher sedimentation rate (70-120S) than the bulk of the solubilized DNA (40S). The electron microscopic observation showed the complex to be an aggregate of several DNA molecules with a local structure containing amorphous materials which stained black and bushes of RNA. This confirmed biochemical evidences suggesting that the complex is an intermolecular aggregate of the purA-DNA-protein-RNA complex.