Force amplification response of actin filaments under confined compression

Greene, George W.; Anderson, Travers H.; Zeng, Hongbo; Zappone, Bruno; Israelachvili, Jacob N.

doi:10.1073/pnas.0812064106

Cited by 27 publications

(23 citation statements)

References 21 publications

(23 reference statements)

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“…1B). A previous observation using the compression of actin filaments between two thin mica plates observed a stiffening of these filaments under force (Greene et al, 2009), which appears to be the same phenomenon as the rigidification of F-actin observed in thin ice (Galkin et al, 2012). In order to reduce structural heterogeneity within the actin filament to achieve the highest possible resolution we used blotting conditions (see Materials and Methods) which yielded very thin ice (Fig.…”

Section: Resultssupporting

confidence: 62%

Near-Atomic Resolution for One State of F-Actin

Galkin

Orlova

Vos³

et al. 2015

Structure

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Actin functions as a helical polymer, F-actin, but attempts to build an atomic model for this filament have been hampered by the fact that the filament cannot be crystallized and by structural heterogeneity. We have used a direct electron detector, electron cryo-microscopy and the forces imposed on actin filaments in thin films to reconstruct one state of the filament at 4.7 Å resolution, which allows for building the first reliable pseudo-atomic model of F-actin. We also report a different state of the filament where actin protomers adopt a conformation observed in the crystal structure of the G-actin-profilin complex with an open ATP-binding cleft. Comparison of the two structural states provides new insights into ATP-hydrolysis and filament dynamics. The atomic model provides a framework for understanding why every buried residue in actin has been under intense selective pressure.

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Section: Resultssupporting

confidence: 62%

Near-Atomic Resolution for One State of F-Actin

Galkin

Orlova

Vos³

et al. 2015

Structure

133

147

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“…Tomographic reconstructions of axonemes in thin ice showed extreme flattening, with the suggestion that the flattening arose from this large surface tension [38]. Most importantly, observations have already been made by Greene et al [39] about F-actin filaments confined between two mica surfaces (Fig. 2), which appear to be a good analog for the thin films being used for cryo-EM.…”

Section: Reconciling Two Different Viewsmentioning

confidence: 81%

Actin Filaments as Tension Sensors

2012

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The field of mechanobiology has witnessed an explosive growth over the past several years as interest has greatly increased in understanding how mechanical forces are transduced by cells and how cells migrate, adhere and generate traction. Actin, a highly abundant and anomalously conserved protein, plays a large role in forming the dynamic cytoskeleton that is so essential for cell form, motility and mechanosensitivity. While the actin filament (F-actin) has been viewed as dynamic in terms of polymerization and depolymerization, new results suggest that F-actin itself may function as a highly dynamic tension sensor. This property may help explain the unusual conservation of actin’s sequence, as well as shed further light on actin’s essential role in structures from sarcomeres to stress fibers.

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“…The mechanical response of an actin network confined between two rigid flat surfaces has been probed using a surface force apparatus (SFA) in [29] and using an atomic force microscope (AFM) in [30]. Both experiments reported a load history-dependent mechanical response, which presumably reflects a complex interplay between buckling and polymerization forces.…”

Section: Related Experimental Work In Connection With the Modelmentioning

confidence: 99%

Condensation of actin filaments pushing against a barrier

et al. 2011

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We develop a model to describe the force generated by the polymerization of an array of parallel biofilaments. The filaments are assumed to be coupled only through mechanical contact with a movable barrier. We calculate the filament density distribution and the force-velocity relation with a mean-field approach combined with simulations. We identify two regimes: a non-condensed regime at low force in which filaments are spread out spatially, and a condensed regime at high force in which filaments accumulate near the barrier. We confirm a result previously known from other related studies, namely that the stall force is equal to N times the stall force of a single filament. In the model studied here, the approach to stalling is very slow, and the velocity is practically zero at forces significantly lower than the stall force.

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Force amplification response of actin filaments under confined compression

Cited by 27 publications

References 21 publications

Near-Atomic Resolution for One State of F-Actin

Near-Atomic Resolution for One State of F-Actin

Actin Filaments as Tension Sensors

Condensation of actin filaments pushing against a barrier

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