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Macromolecular crowding modulates actin bundle formation induced by actin crosslinking proteins
Author(s) -
Park Jinho,
Lee Myeongsang,
Kang Hyeran
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.779.28
Subject(s) - fascin , actin binding protein , lamellipodium , macromolecular crowding , actin , filopodia , actin remodeling , total internal reflection fluorescence microscope , biophysics , chemistry , mdia1 , microbiology and biotechnology , microfilament , filamin , actin cytoskeleton , macromolecule , biology , in vitro , biochemistry , cytoskeleton , cell migration , cell , membrane
Bundles of filamentous actin generate high ordered cellular structures including filopodia and lamellipodia with the help of actin binding proteins. α‐actinin and fascin are essential actin crosslinking proteins that affect the mechanical properties of bundles. While the roles of both actin binding proteins in bundling have been well studied in dilute buffer conditions, how they affect bundle formation in crowded environments is not established. Here, we investigate the effects of macromolecular crowding on actin bundles crosslinked by α‐actinin and fascin in vitro and in silico . Time‐dependent bundling processes by both proteins were monitored in the presence of the polymeric crowding agent polyethylene glycol (PEG) using total internal reflection fluorescence (TIRF) microscopy. Biophysical analysis show that PEG reduces the amount and average lengths of α‐actinin‐induced bundles but promotes the formation of thicker bundles induced by fascin. Utilizing molecular dynamics (MD) simulations, we evaluated the interaction between actin filaments and bundling proteins by measuring the contact area and the number of hydrogen bonds. The simulation results demonstrate that PEG increases the binding affinities between actin and binding domain of fascin, while lowering the affinities between actin and α‐actinin. Taken together, our work suggests that crowded environments may modulate actin bundling induced by actin binding proteins in vivo . Support or Funding Information This study was supported by the UCF start‐up fund and In‐House grant for Hyeran Kang. We acknowledge the computational time from UCF stokes cluster. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .