  Self-organization of proteins in space and time is of crucial importance for
the functioning of cellular processes. Often, this organization takes place in
the presence of strong random fluctuations due to the small number of molecules
involved. We report on stochastic switching of the Min-protein distributions
between the two cell halves in short Escherichia coli cells. A computational
model provides strong evidence that the macroscopic switching is rooted in
microscopic noise on the molecular scale. In longer bacteria, the switching
turns into regular oscillations that are required for positioning of the
division plane. As the pattern becomes more regular, cell-to-cell variability
also lessens, indicating cell length-dependent regulation of Min-protein
activity.
