Achievement

Trainee Dan Reeves (Physics) has been collaborating with the Goode lab (Biology) on the mechanism by which the actin binding protein formin regulates the rate of actin filament growth. Dan has calculated the rate of actin capture and delivery to the growing tip as a function of the length of the flexible tether, the number of binding sites, and their location on the tether. This involved solving a novel diffusion to capture problem where the binding site sits on a diffusing polymer. To check his theory Dan has also written a Brownian dynamics simulation for diffusion to capture by a flexible polymer.

Dan used these models to compute the expected speed-up factors for all the naturally occurring formins that have been characterized, and he was able to recapitulate the available experimental results. Dan has made predictions for mutant formins whose flexible domains have variable length, and he has suggested experiments now ongoing in the Goode and Dogic labs.