Side-binding proteins modulate actin filament dynamics

Crevenna, Álvaro H.; Arciniega, Marcelino; Dupont, Aurélie; Kowalska, Kaja; Lange, Oliver; Wedlich‐Söldner, Roland; Lamb, Don C.

doi:10.1101/008128

Cited by 6 publications

(9 citation statements)

References 71 publications

(85 reference statements)

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“…This suggests that a mechanical process is involved in actin monomers' removal at the actin filament tip. One possible mechanism could be through the modulation of the torsion of the filaments 25 . In this case, the polymerization kinetics is expected to depend on the filament length with a twist gradient inversely proportional to the length.…”

Section: Discussionmentioning

confidence: 99%

A new actin depolymerase: a Myosin 1 motor

Pernier

Kusters

Bousquet

et al. 2018

Preprint

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Sentence summary Due to its catch bond, Myosin 1b depolymerizes sliding actin filaments at their barbed end by exerting a prolonged force.All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/375923 doi: bioRxiv preprint first posted online Jul. 24, 2018; 2 AbstractThe regulation of actin dynamics is essential for various cellular processes. Former evidence suggests a correlation between the function of non-conventional myosin motors and actin dynamics. We investigate the contribution of the catch-bond Myosin1b to actin dynamics using sliding motility assays. We observe that sliding on Myosin1b immobilized or bound to a fluid bilayer enhances actin depolymerization at the barbed end, while sliding on the weak catch-bond MyosinII has no effect. Our theoretical model supports that the catch-bond prolongs the attachment time of the motor at the barbed end due to the friction force exerted by the sliding filament; thereby this motor exerts a sufficient force on this end to promote depolymerization. This work reveals a non-conventional myosin motor as a new type of depolymerase.All rights reserved. No reuse allowed without permission.(which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/375923 doi: bioRxiv preprint first posted online Jul. 24, 2018; 3 Actin filaments (F-actin) form a variety of dynamical architectures that govern cell morphology and cell movements. The dynamics of the actin networks are regulated in space and time by the assembly and disassembly of actin polymers under the control of regulatory proteins. Cortical actin organizes lateral movement of transmembrane proteins and participates in membrane signaling by interacting transiently with the plasma membrane (1). One class of actin-associated molecular motors, the single-headed myosin 1 proteins, bridges cortical actin to the plasma membrane. Polymerization of actin filaments at the plasma membrane generates forces on the membrane as well as on their membrane linkers. Inversely myosin 1 can exert and sustain pN forces on F-actin (2).This important class of myosins contains a motor domain at its N-terminus that binds Factin in response to ATP hydrolysis, a light chain binding domain (LCBD) that binds calmodulin (in most cases), and a Tail domain at the C-terminus (Fig. 1A) (3). The Tail domain encompasses a tail homology domain (TH1) with a pleckstrin homology motif (PH) that binds phosphoinositides (Fig. 1A). Beside the involvement of myosin 1 proteins in a large variety of cellular processes including cell migration and membrane trafficking (3), manipulation of myosin 1 expression has revealed a correlation between these myosins and actin network architecture (4-7). In particular, down-or overexpression of one of the...

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Section: Discussionmentioning

confidence: 99%

A new actin depolymerase: a Myosin 1 motor

Pernier

Kusters

Bousquet

et al. 2018

Preprint

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“…Reconstitution of actin based processes in vitro and direct observation of their dynamics at the single filament and single molecule level by timelapse fluorescence microscopy represents a powerful approach to dissect the role of actinbinding proteins on filament properties [Crevenna et al, 2015;Hsiao et al, 2015;Jansen et al, 2015;Johnston et al, 2015]. However, it is important to consider and assess potential artifacts associated with the surface chemistry of attaching actin filaments to the surface.…”

Section: Reconstitution Of Filaments On Surfacesmentioning

confidence: 99%

“…Even though actin filaments in cells can also be bound to surfaces (e.g., to membranes), this attachment mode may hinder access of large sidebinding proteins (i.e., those to be studied in the assay) to the filament and thus affect their interaction kinetics. In addition, side-binding proteins used for immobilization may have overlapping binding sites on the filament with the protein to be studied or could induce structural changes in the filament [Crevenna et al, 2015]. To overcome these limitations, actin filaments can be attached to the surface at one end.…”

Section: Reconstitution Of Filaments On Surfacesmentioning

confidence: 99%

“…Fluorescence imaging of actin filaments reconstituted in vitro has emerged as an important tool to observe the kinetics of actin polymerization and the interactions with actinbinding proteins at the level of individual filaments [J egou et al, 2011;Crevenna et al, 2015;Gressin et al, 2015;Hsiao et al, 2015;Schmidt et al, 2015]. To facilitate observation, actin filaments are commonly attached to the surface of a modified glass coverslip at multiple points along their length and appear as curved lines in the fluorescence image [Breitsprecher et al, 2009;Smith et al, 2014].…”

mentioning

confidence: 99%

“…A key question in these reconstitution assays is whether the surface chemistry and in particular the method for anchoring filaments affects their properties, e.g., as observed in the effect of different side-binding proteins on actin elongation [Crevenna et al, 2015]. It is unknown to what extent geometric constraints or filament motions can hinder the access of side-binding proteins to the filament.…”

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Effect of surface chemistry on tropomyosin binding to actin filaments on surfaces

et al. 2016

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Reconstitution of actin filaments on surfaces for observation of filament-associated protein dynamics by fluorescence microscopy is currently an exciting field in biophysics. Here we examine the effects of attaching actin filaments to surfaces on the binding and dissociation kinetics of a fluorescence-labeled tropomyosin, a rod-shaped protein that forms continuous strands wrapping around the actin filament. Two attachment modalities of the actin to the surface are explored: where the actin filament is attached to the surface at multiple points along its length; and where the actin filament is attached at one end and aligned parallel to the surface by buffer flow. To facilitate analysis of actin-binding protein dynamics, we have developed a software tool for the viewing, tracing and analysis of filaments and co-localized species in noisy fluorescence timelapse images. Our analysis shows that the interaction of tropomyosin with actin filaments is similar for both attachment modalities. © 2016 Wiley Periodicals, Inc.

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A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

Asante-Asamani

Grange

Rawal

et al. 2020

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Blebs, pressure driven protrusions of the plasma membrane, facilitate the movement of cells such as the soil amoeba Dictyostelium discoideum and other eukaryotes such as white blood cells and cancer cells. Blebs initiate or nucleate when proteins connecting the membrane to the cortex detach, either as a result of a rupture of the cortex or as a direct consequence of a build up in hydrostatic pressure. While linker detachment resulting from excess hydrostatic pressure is well understood, the mechanism by which cells rupture their cortex in locations of bleb formation is not so clear. Consequently, existing predictive models of bleb site selection do not account for it. To resolve this, we propose a model for bleb initiation which combines the geometric forces on the cell cortex/membrane complex with the underlying activity of actin binding proteins. In our model gaps, resulting from a rupture of the cortex, form at locations of high membrane energy where an accumulation of myosin II helps to weaken the cortex. We validate this model in part through a membrane energy functional which combines stresses on the cell boundary from membrane tension, curvature, membrane-cortex linker tension with hydrostatic pressure. Application of this functional to microscopy images of chemotaxing Dictyostelium discoideum cells identifies bleb nucleation sites at the highest energy locations 96.7% of the time. Sensitivity analysis of the model components points to membrane tension and hydrostatic pressure, all of which are regulated by myosin II, as critical to model predictability. Furthermore, microscopy reveals discrete clusters of myosin II along the leading edge of the cell, with blebs emerging from 80% of these sites. Together, our findings suggest a critical role for myosin II in bleb initiation through the formation of gaps and provides a predictive mathematical model for quantitative studies of blebbing. Author summaryEukaryotic cells such as white blood cells and cancer cells have been observed to move by making spherical herniation of their plasma membrane, referred to as blebs. The precise mechanism by which cells select locations around their boundary to initiate blebs is unclear. We hypothesize that blebs initiate at locations of high membrane energy where an accumulation of myosin II helps to rupture the cortex and/or detach linker proteins. We test this hypothesis by formulating a free energy functional representation of membrane energy to predict where blebs will initiate. The functional March 16, 2020 1/19 accounts for geometric forces due to membrane tension, curvature and membrane-cortex linker tension as well as hydrostatic pressure. Application of the functional to data from the soil amoeba, Dictyostelium disodium, identifies blebs at the highest energy locations over 90% of the time. Sensitivity analysis of model components points to membrane tension and hydrostatic pressure, all influenced by myosin II, as major forces driving bleb initiation. Additionally, we observe clusters of myosin II at locations of bleb ...

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Side-binding proteins modulate actin filament dynamics

Cited by 6 publications

References 71 publications

A new actin depolymerase: a Myosin 1 motor

A new actin depolymerase: a Myosin 1 motor

Effect of surface chemistry on tropomyosin binding to actin filaments on surfaces

A bleb initiation model for chemotaxis suggests a role for myosin II clusters and cortex rupture

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