Claude King
“Investigating the Effects of Twinfilin Phosphorylation on Catalyzing Actin Filament Depolymerization”
Claude King III, Rey Aguilar, Denise Hilton, Bruce Goode
Hampton University / Chemical Engineering
Hosted by Goode's Lab
Abstract
Essential biological processes, such as cytokinesis, endocytosis and cellular motility, rely on the rapid rearrangement of the actin cytoskeletal network. Although actin disassembly happens slowly in vitro, cells have adapted an array of proteins that work in concert to achieve robust disassembly. Recently, Twinfilin was shown to catalyze the depolymerization of actin filaments from both the barbed end and the pointed end.
Twinfilin is a member of the actin depolymerization factor homology (ADF-H) family of proteins which all share a highly conserved actin binding domain. Twinfilin is unique in its structure, consisting of two ADF-H domains bound by a linker and followed by a C-terminal tail. Another ADF-H protein, Cofilin, is inactivated by phosphorylation of a residue at the N-terminus. Interestingly, this residue is highly conserved in Twinfilin homologues.
This study investigated the possibility that phosphorylation of Twinfilin would affect actin filament depolymerization. Purified phosphomimetic mutants of mammalian Twinfilin were used in bulk fluorescence disassembly assays and Total Internal Reflection Fluorescence (TIRF) microscopy assays to measure end depolymerization kinetics using labeled, tethered actin filaments in the presence of Twinfilin and CAP 1.
This study revealed that phosphorylation at this site in Twinfilin did not alter its depolymerization activities, even in conjunction with CAP 1. This likely suggests that Twinfilin is either not regulated at all or regulated through some other mechanism rather than N-terminus phosphorylation
Support
MRSEC REU