Scheme of the different ω₂ and δ₂ variants used and their contribution to plasmid stability.

<p>Essential domains in the δ₂ protein are highlighted and the asterisks indicate the position of the mutated residues. The Par^- pHP14 vector and derivatives (~8 copies per cell) bearing the whole pSM19035 <i>par</i> locus or part of it were grown in LB medium at 30°C for at least 120 generations of growth, and plasmid stability was measured as described in the Materials and Methods section.