Competition for delivery of profilin-actin to barbed ends limits the rate of formin-mediated actin filament elongation.

ABSTRACT: Formins direct the elongation of unbranched actin filaments by binding their barbed ends and processively stepping onto incoming actin monomers to incorporate them into the filament. Binding of profilin to actin monomers creates profilin-actin complexes, which then bind polyproline tracts located in formin homology 1 (FH1) domains. Diffusion of these natively disordered domains enables direct delivery of profilin-actin to the barbed end, speeding the rate of filament elongation. In this study, we investigated the mechanism of coordinated actin delivery from the multiple polyproline tracts in formin FH1 domains. We found that each polyproline tract can efficiently mediate polymerization, but that all tracts do not generate the same rate of elongation. In WT FH1 domains, the multiple polypro

SUBMITTER: Zweifel ME 

PROVIDER: S-EPMC7135983 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature