Two-dimensional model of bipolar PopZ polymerization in caulobacter crescentus

The asymmetric location of proteins is crucial to the Caulobacter cell cycle. At cell division, the landmark protein PopZ is located at the old ends of the newborn cells, and later in the cell cycle PopZ adopts a bipolar pattern in the predivisional cell. The polar localization of PopZ plays a determining role in the intracellular location of certain key cell cycle regulators and in tethering the replicated chromosome to the two ends of the cell. PopZ polymerizes at the poles of a Caulobacter cell by a self-organizing mechanism. Experiments demonstrate that popZ gene replication is indispensable in forming bipolar PopZ patterns. Hence, to study the mechanism of PopZ bipolarity, we propose a model of spatiotemporal organization in two spatial dimensions, based on a Turing mechanism of pattern formation in coordination with chromosome replication and segregation. We explore PopZ patterns on domains of different shapes and different locations of popZ genes. Both deterministic and stochastic simulations capture the observed variations in the location and timing of PopZ polymerization.