Explaining the in vivo–in vitro transition of Min protein patterns

Intracellular processes must be precisely organized in space and time. A paradigmatic example is the symmetric division of bacteria, which, in E. coli, is orchestrated by the ATP-driven oscillation of Min proteins between the cell poles. Remarkably, two proteins of the Min system are sufficient for this pattern-formation process and also form a kaleidoscope of reaction–diffusion patterns in vitro. Although only two proteins interact, we lack a comprehensive understanding of the patterns in vivo and in vitro. Here, we show theoretically that changes in the membrane-binding of one of the proteins, MinE, explain the differences between patterns in vivo and in vitro. We verify this prediction in vitro by constructing the first comprehensive pattern phase diagram using wild-type proteins and by removing MinE’s membrane targeting sequence. This shows that a conceptual reaction–diffusion system grounded in the known biochemistry of the Min proteins captures their spatiotemporal self-organization quantitatively. Our work offers an instructive platform to study the physiological implications of and the physical principles underlying the rich phenomenology of intracellular protein patterns.