A stochastic model for protein localization in Caulobacter crescentus bacterium

Abstract

Caulobacter crescentus bacterial cells use a minimal three component Par partition system to segregate DNA during asymmetric division. Precise division plane placement is tightly controlled by MipZ protein gradients that are thought to interact with Par proteins. How these complex protein interactions generate precise measurements in the face of stochastic fluctuations is of significant interest. Here, we first developed a detailed computational model used to study key interactions between Par and MipZ proteins that control chromosome segregation. In addition, we developed a minimal intermittent-search model that captured key ParB/ParA interactions in support of chromosome copy movement. Lastly, we found the competition between ParA and MipZ proteins for ParB complex binding sites to be sufficient in order to generate experimentally observed MipZ bipolar gradients. Our models provide a framework to study how the movement of the DNA copy could communicate with the division site placement proteins in Caulobacter crescentus cells.