Isolation of membrane-associated folded chromosomes from Escherichia coli: effect of protein synthesis inhibition.

The sedimentation properties of membrane-associated folded chromosomes prepared from Escherichia coli TAU-bar at 0 to 4 C were studied. Utilizing a modification of the procedure of Stonington and Pettijohn (1971), quantitative yields of membrane-associated folded chromosomes may be obtained. Folded chromosomes remained associated with the cell envelope during their replication and after completion of residual synthesis in the absence of required amino acids, as demonstrated by sedimentation velocities and the presence of high levels of cosedimenting protein. Membrane-associated folded chromosomes isolated from amino acid-starved cells sedimented more rapidly than membrane-associated folded chromosomes isolated from exponentially growing cells.