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Effects of basic calponin on the flexural mechanics and stability of F‐actin
Author(s) -
Jensen Mikkel Herholdt,
Watt James,
Hodgkinson Julie L.,
Gallant Cynthia,
Appel Sarah,
ElMezgueldi Mohammed,
Angelini Thomas E.,
Morgan Kathleen G.,
Lehman William,
Moore Jeffrey R.
Publication year - 2012
Publication title -
cytoskeleton
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 86
eISSN - 1949-3592
pISSN - 1949-3584
DOI - 10.1002/cm.20548
Subject(s) - calponin , actin , cytoskeleton , protein filament , biology , biophysics , microbiology and biotechnology , actin remodeling , actin cytoskeleton , cell , biochemistry
Abstract The cellular actin cytoskeleton plays a central role in the ability of cells to properly sense, propagate, and respond to external stresses and other mechanical stimuli. Calponin, an actin‐binding protein found both in muscle and non‐muscle cells, has been implicated in actin cytoskeletal organization and regulation. In this work, we studied the mechanical and structural interaction of actin with basic calponin, a differentiation marker in smooth muscle cells, on a single filament level. We imaged fluorescently labeled thermally fluctuating actin filaments and found that at moderate calponin binding densities, actin filaments were more flexible, evident as a reduction in persistence length from 8.0 to 5.8 μm. When calponin‐decorated actin filaments were subjected to shear, we observed a marked reduction of filament lengths after decoration with calponin, which we argue was due to shear‐induced filament rupture rather than depolymerization. This increased shear susceptibility was exacerbated with calponin concentration. Cryo‐electron microscopy results confirmed previously published negative stain electron microscopy results and suggested alterations in actin involving actin subdomain 2. A weakening of F‐actin intermolecular association is discussed as the underlying cause of the observed mechanical perturbations. © 2011 Wiley Periodicals, Inc