Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 42: Cytoskeletal filaments (joint BP/CPP)

BP 42.6: Talk

Thursday, March 19, 2015, 11:00–11:15, H 1028

Quantifying protein diffusion and capture on filaments — •Emanuel Reithmann, Louis Reese, and Erwin Frey — Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität, München

The functional relevance of regulating proteins is often restricted to specific binding sites such as the ends of microtubules or actin-filaments. A localization of proteins on these functional sites is of great importance. In this respect, recent experimental studies suggested that several key players involved in regulation of microtubules and actin-filaments utilize a one-dimensional diffusive motion on the respective filament to target the functional end. We present a quantitative theory for a diffusion and capture process, where proteins diffuse on a filament and stop diffusion when reaching the filament's end. It is found that end-association after one-dimensional diffusion is highly efficient as compared to direct binding from solution/cytoplasm. As a consequence, diffusion and capture substantially enhances the reaction velocity of enzymatic reactions, where proteins and filament ends are to each other as enzyme and substrate. We show that the reaction velocity ensuing from diffusion and capture can effectively be computed within a Michaelis-Menten framework. We predict that diffusion and capture would significantly beat the (three-dimensional) Smoluchowski diffusion limit for the rate of direct protein association to filament ends for practically all proteins that are known to diffuse on microtubules and actin-filaments.