Self-organisation and positioning of bacterial protein clusters

Many cellular processes require sub-cellular positioning of proteins. This can be due to passive mechanisms such as recruitment by existing landmarks or curvature sensing. However, in bacteria active self-positioning is likely to play a role in multiple processes, including the positioning of the future division site and cytoplasmic protein clusters. How can such dynamic clusters be formed and positioned? Here, we present a model for the self-organization and positioning of dynamic protein clusters into regularly repeating patterns based on a phase-locked Turing pattern. A single peak in the concentration is always positioned at mid-domain (mid-cell) while two peaks are positioned one at each quarter-position etc. Furthermore, domain growth results in peak-splitting and pattern doubling. We argue that the model may explain the regular positioning of the highly conserved Structural Maintenance of Chromosomes (SMC) complexes on the bacterial nucleoid and provides an attractive mechanism for the self-positioning of dynamic protein clusters in other systems.