Size-control of multiple structures with filament severing

Living cells contain a variety of cytoskeletal structures which serve specific functions related to their characteristic sizes and shapes. These structures are dynamic and assemble in a shared pool of their building blocks. Remarkably, cohabitating structures in this shared resource environment are able to maintain their specific size despite rapidly exchanging their building blocks in the shared pool. The mechanisms used by cells to enable this are not well understood. Here we consider the role of severing proteins in the assembly and size-control of coexisting structures. We study this process theoretically using master equations and with simulations. We statistically analyze the simulated length trajectories, and describe the probability distribution of lengths and the resulting length fluctuations as a function of different parameters of the theoretical model. Our study describes how severing proteins can aid in maintaining sizes of multiple competing structures in a pool of their building blocks