Deoxyribonucleic acid-envelope complexes from Escherichia coli. A complex-specific protein and its possible function for the stability of the complex.

The different Escherichia coli envelope fractions (cell wall, cytoplasmic membrane, and DNA-envelope complex fragments) were isolated by free-flow electrophoresis and analyzed by sodium dodecylsulfate-acrylamide gel electrophoresis. The DNA-envelope complex fragments possess a specific protein (mol wt 80,000-90,000). Upon treatment with trypsin, this protein disappears and the complex breaks down, thus releasing DNA, cell wall, and cytoplasmic membrane. Disaggregation of the complex can also be achieved by high salt concentrations. Lysozyme treatment dissolves the murein layer within the complex but does not disaggregate the complex. From these and other results on the stability of the DNA-envelope complex, conclusions can be drawn about the possible linkage within the described envelope particles.