The folded genome of Escherichia coli isolated in a protein-DNA-RNA complex.

The DNA of Escherichia coli has been isolated in a compact structure containing small amounts of protein and RNA and having a sedimentation coefficient of approximately 3200 S. The molecular weight of the DNA in the complex is very large (probably higher than 10(9)); the protein is predominantly core RNA polymerase; the RNA is chiefly nascent messenger and ribosomal chains. Solutions containing the complex have low viscosities; this plus its sedimentation rate suggest that the DNA is in a tightly folded conformation. The DNA unfolds after exposure to RNase or heat; this indicates that an RNA component of the complex is involved in stabilizing the structure.