Dynamics and Scaling of Competitive Actin Architectures

Cells constantly experience environmental changes requiring a fast adaptation of their different actin structures. However, the mechanisms governing the size and dynamics of these multiple actin structures remain unknown. We have developed a bottom-up approach to identify the key molecular mechanisms that determine the size and coexistence of multiple competing actin architectures. We use a reconstituted system consisting of purified proteins and substrates to localize actin polymerization in microwells, enabling us to work with a limited number of components. With this system, we reconstituted several dynamic actin architectures, competing for a limited pool of protein, over a period of multiple hours. I will show how we used this system to study the limits of scaling in dynamic structures, as well as the limits of coexistence in actin networks under resource-limited conditions. Finally, I will show how we can recapitulate these results in a complementary cellular system, in which we have demonstrated that an increase in spreading area leads to a decrease in overall turnover, due to a predominance of structures with low turnover.