Unfolding of the chromosome of Escherichia coli after treatment with rifampicin.

Until recently it has been assumed that the factors being responsible for the condensation of the DNA in the nucleoid of Escherichia coli are destroyed by rifampicin because it has been impossible to obtain folded chromosomes from cells treated with this inhibitor. In this paper it is shown by viscosity and sedimentation measurements that unfolding of the DNA does not take place during the process of the cell lysis as it should be predicted from this assumption, but is occurring distinctly afterwards. Since the observed unfolding process is too slow to be caused simply by molecular movements it is concluded that it is brought about by the action of salts or detergents of the lysis medium. The structure of the nucleoid is still intact in vivo despite inhibition of RNA synthesis by rifampicin.