The constraining process depends on MatP and ZapB.

<p>(A–D) Travelled distance of different markers in strains deleted for <i>zapB</i>, deleted for segment rins2 and <i>zapB</i>, and in wt strain. The representation is the same as in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002672#pgen-1002672-g002" target="_blank">Figure 2</a>. (A) strain with a deletion of <i>zapB</i> (markers Ori-3, NSR-2, Right-2 (R2), Ter-3, Left-2 (L2), Left-1 (L1) are indicated from left to right). (B) strain with a deletion of <i>zapB</i> and rins2 (markers Ori-3, NSR-2, NSR-5, Right-2 (R2) are indicated from left to right). (C) small cells of wt strain before Ter MD segregation at mid-cell (markers Ori-3, NSR-5, Right-2 (R2), Ter-3 are indicated from left to right). (D) small cells of strain Δrins2 before Ter MD segregation at mid-cell (markers Ori-3, NSR-2, NSR-5, Right-2 (R2), Ter-3, NSL-4 are indicated from left to right). (E) Quantification of the co-localisation of the MatP-mCherry focus (red) with a chromosomal <i>parS</i> tag bound by ParB-GFP (green). The percentage of cells presenting different interfocal distances is given (left column). In the top lane, the MatP-mCherry focus co-localizes with the Ter-3 marker in the wt strain. The interfocal distance is smaller than 0.4 µm in more than 90% of the cells. In the central lane, the MatP-mCherry focus does not co-localize with the NSR-2 marker in the strain LC13-R127-B^O-NSR with a transposition of the Right MD between the Ori MD and the NS^Right region (see chromosome configuration in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1002672#pgen-1002672-g002" target="_blank">Figure 2</a>). The interfocal distance is greater than 0.3 µm in almost 90% of the cells. In bottom lane, the MatP-mCherry focus does not co-localize with the Right-2 marker in the wt strain. The interfocal distance is greater than 0.3 µm in 90% of the cells.