Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle?

Månsson, Alf; Ušaj, Marko; Moretto, Luisa; Rassier, Dilson E.

doi:10.3390/ijms19071863

Cited by 32 publications

(49 citation statements)

References 266 publications

(542 reference statements)

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“…It is of interest to consider the present results in relation to variability between different single molecule studies in key myosin properties such as step length, actomyosin stiffness and cross-bridge force (Kaya and Higuchi 2013 ; Månsson et al 2018 ). These differences are largely attributed to the use of different types of single molecule preparations and different details of the force-measurement techniques and analyses (Kaya and Higuchi 2013 ; Månsson et al 2018 ). However, the possibility should also be considered that part of the variation arises because affinity purification has been used in some studies but not in others.…”

Section: Discussionmentioning

confidence: 99%

Comparative analysis of widely used methods to remove nonfunctional myosin heads for the in vitro motility assay

Rahman

Salhotra

Månsson

2018

J Muscle Res Cell Motil

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The in vitro motility assay allows studies of muscle contraction through observation of actin filament propulsion by surface-adsorbed myosin motors or motor fragments isolated from muscle. A possible problem is that motility may be compromised by nonfunctional, “dead”, motors, obtained in the isolation process. Here we investigate the effects on motile function of two approaches designed to eliminate the effects of these dead motors. We first tested the removal of heavy meromyosin (HMM) molecules with ATP-insensitive “dead” heads by pelleting them with actin filaments, using ultracentrifugation in the presence of 1 mM MgATP (“affinity purification”). Alternatively we incubated motility assay flow cells, after HMM surface adsorption, with non-fluorescent “blocking actin” (1 µM) to block the dead heads. Both affinity purification and use of blocking actin increased the fraction of motile filaments compared to control conditions. However, affinity purification significantly reduced the actin sliding speed in five out of seven experiments on silanized surfaces and in one out of four experiments on nitrocellulose surfaces. Similar effects on velocity were not observed with the use of blocking actin. However, a reduced speed was also seen (without affinity purification) if HMM or myosin subfragment 1 was mixed with 1 mM MgATP before and during surface adsorption. We conclude that affinity purification can produce unexpected effects that may complicate the interpretation of in vitro motility assays and other experiments with surface adsorbed HMM, e.g. single molecule mechanics experiments. The presence of MgATP during incubation with myosin motor fragments is critical for the complicating effects. Electronic supplementary material The online version of this article (10.1007/s10974-019-09505-1) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Comparative analysis of widely used methods to remove nonfunctional myosin heads for the in vitro motility assay

Rahman

Salhotra

Månsson

2018

J Muscle Res Cell Motil

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“…( 27 )). Furthermore, if the elastic properties in single-molecule studies differ from those of the cross-bridges in muscle, this has implications for understanding the constraining effects of the ordered myofilament lattice and/or accessory proteins in the muscle sarcomere ( 38 ). Before more detailed investigations, the first step is to clarify whether the characteristics of the cross-bridge elasticity in muscle really differ from those found in single molecules.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, because of lack of detailed modeling of the muscle fiber data under rigor conditions, it is not clear whether the nonlinearity found previously ( 24 ) is consistent with the nonlinearity observed in single molecules ( 29 ). An approach to address these questions is to use “bottom-up” modeling ( 38 ), i.e., to incorporate the nonlinear cross-bridge elastic properties from single-molecule data ( 29 ) into appropriate statistical cross-bridge models ( 5 ) for muscle and then test whether these models account for the muscle properties in rigor as well as under physiological conditions.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Actomyosin Elasticity in Muscle?

Månsson

Persson

Shalabi

et al. 2019

Biophysical Journal

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Cyclic interactions between myosin II motor domains and actin filaments that are powered by turnover of ATP underlie muscle contraction and have key roles in motility of nonmuscle cells. The elastic characteristics of actin-myosin cross-bridges are central in the force-generating process, and disturbances in these properties may lead to disease. Although the prevailing paradigm is that the cross-bridge elasticity is linear (Hookean), recent single-molecule studies suggest otherwise. Despite convincing evidence for substantial nonlinearity of the cross-bridge elasticity in the single-molecule work, this finding has had limited influence on muscle physiology and physiology of other ordered cellular actin-myosin ensembles. Here, we use a biophysical modeling approach to close the gap between single molecules and physiology. The model is used for analysis of available experimental results in the light of possible nonlinearity of the cross-bridge elasticity. We consider results obtained both under rigor conditions (in the absence of ATP) and during active muscle contraction. Our results suggest that a wide range of experimental findings from mechanical experiments on muscle cells are consistent with nonlinear actin-myosin elasticity similar to that previously found in single molecules. Indeed, the introduction of nonlinear cross-bridge elasticity into the model improves the reproduction of key experimental results and eliminates the need for force dependence of the ATP-induced detachment rate, consistent with observations in other single-molecule studies. The findings have significant implications for the understanding of key features of actin-myosin-based production of force and motion in living cells, particularly in muscle, and for the interpretation of experimental results that rely on stiffness measurements on cells or myofibrils.

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“… Although the authors developed methods to analyze ultrafast force-clamp data [5] , [6] , improvements in data analysis, for example using differential detection between the two trap channels [7] , correlative detection [8] , step detection algorithms [9] , might reveal hidden properties on the acto-myosin interaction. Models of acto-myosin interaction rely to a great extent on single molecule data [10] , [11] , [12] , [13] , [14] . Single molecule high-resolution data are therefore fundamental to define and test such models.…”

mentioning

confidence: 99%

“…Models of acto-myosin interaction rely to a great extent on single molecule data [10] , [11] , [12] , [13] , [14] . Single molecule high-resolution data are therefore fundamental to define and test such models.…”

mentioning

confidence: 99%

Ultra-fast force-clamp spectroscopy data on the interaction between skeletal muscle myosin and actin

Maffei

Beneventi²,

Canepari

et al. 2019

Data in Brief

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Ultrafast force-clamp spectroscopy is a single molecule technique based on laser tweezers with sub-millisecond and sub-nanometer resolution. The technique has been successfully applied to investigate the rapid conformational changes that occur when a myosin II motor from skeletal muscle interacts with an actin filament. Here, we share data on the kinetics of such interaction and experimental records collected under different forces [1]. The data can be valuable for researchers interested in the mechanosensitive properties of myosin II, both from an experimental and modeling point of view. The data is related to the research article “ultrafast force-clamp spectroscopy of single molecules reveals load dependence of myosin working stroke” [2].

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Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle?

Cited by 32 publications

References 266 publications

Comparative analysis of widely used methods to remove nonfunctional myosin heads for the in vitro motility assay

Comparative analysis of widely used methods to remove nonfunctional myosin heads for the in vitro motility assay

Nonlinear Actomyosin Elasticity in Muscle?

Ultra-fast force-clamp spectroscopy data on the interaction between skeletal muscle myosin and actin

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