Direct observation of motion of single F-actin filaments in the presence of myosin

Yanagida, Toshio; Nakase, Michiyuki; Nishiyama, Katsumi; Oosawa, Fumio

doi:10.1038/307058a0

Cited by 468 publications

(311 citation statements)

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“…Other filament binding proteins (e.g., tropomyosin and myosin) that bind at or near the stiffness site could potentially disrupt site geometry and cation occupancy (21). This may seem at variance with the observed stiffening effects of these proteins (29)(30)(31). However, this could be realized if cation-dependent interactions are replaced with more stabilizing protein-protein interactions (e.g., directly binding adjacent filament subunits).…”

Section: Significancementioning

confidence: 50%

Site-specific cation release drives actin filament severing by vertebrate cofilin

Kang

Bradley

Cao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Actin polymerization powers the directed motility of eukaryotic cells. Sustained motility requires rapid filament turnover and subunit recycling. The essential regulatory protein cofilin accelerates network remodeling by severing actin filaments and increasing the concentration of ends available for elongation and subunit exchange. Although cofilin effects on actin filament assembly dynamics have been extensively studied, the molecular mechanism of cofilin-induced filament severing is not understood. Here we demonstrate that actin filament severing by vertebrate cofilin is driven by the linked dissociation of a single cation that controls filament structure and mechanical properties. Vertebrate cofilin only weakly severs Saccharomyces cerevisiae actin filaments lacking this "stiffness cation" unless a stiffness cation-binding site is engineered into the actin molecule. Moreover, vertebrate cofilin rescues the viability of a S. cerevisiae cofilin deletion mutant only when the stiffness cation site is simultaneously introduced into actin, demonstrating that filament severing is the essential function of cofilin in cells. This work reveals that site-specific interactions with cations serve a key regulatory function in actin filament fragmentation and dynamics.cytoskeleton | persistence length | mechanics | electron cryomicroscopy A ctin polymerization powers the directed motility of eukaryotic cells and some pathogenic bacteria (1-3). Actin assembly also plays critical roles in endocytosis, cytokinesis, and establishment of cell polarity. Sustained motility requires filament disassembly and subunit recycling. The essential regulatory protein cofilin severs actin filaments (4-6), which accelerates actin network reorganization by increasing the concentration of filament ends available for subunit exchange (7).Cofilin binding alters the structure and mechanical properties of filaments, which effectively introduces local "defects" that compromise filament integrity and promote severing (5). Filaments with bound cofilin have altered twist (8, 9) and are more compliant in both bending and twisting than bare filaments (10-13). It has been suggested that deformations in filament shape promote fragmentation at or near regions of topological and mechanical discontinuities, such as boundaries between bare and cofilin-decorated segments along partially decorated filaments (5,12,(14)(15)(16)(17)(18).Cations modulate actin filament structure and mechanical properties (19) and cofilin dissociates filament-associated cations (20), leading us to hypothesize that cation-binding interactions regulate filament severing by cofilin. Cations bind filaments at two discrete and specific sites positioned between adjacent subunits along the long-pitch helix of the filament (19, 21). These cation binding sites are referred to as "polymerization" and "stiffness" sites based on their roles in filament assembly and mechanics, respectively. These discrete sites bind both monovalent and divalent cations with a range of affinities (low millimolar f...

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Section: Significancementioning

confidence: 50%

Site-specific cation release drives actin filament severing by vertebrate cofilin

Kang

Bradley

Cao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Optical microscope techniques have developed greatly during the last 20 years. In 1984, single actin ®laments were made visible by staining with¯uorescent dyes, phalloidin±rhodamin (Yanagida et al 1984). Fortunately, this staining had no in¯uence on the function of actin ®laments.…”

Section: The Unit Machine Of Slidingmentioning

confidence: 99%

The loose coupling mechanism in molecular machines of living cells

Oosawa

2000

Genes to Cells

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Living cells have molecular machines for free energy conversion, for example, sliding machines in muscle and other cells,¯agellar motors in bacteria, and various ion pumps in cell membranes. They are constructed from protein molecules and work in the nm (nanometer), pN (piconewton) and ms (millisecond) ranges, without inertia. In 1980s, a question was raised of whether the input±output or in¯ux±ef¯ux coupling in these molecular machines is tight or loose, and an idea of loose coupling was proposed. Recently, the long-distance multistep sliding of a single myosin head on an actin ®lament, coupled with the hydrolysis of one ATP molecule, was observed by Yanagida's group using highly developed techniques of optical microscopy and micromanipulation. This gave direct evidence for the loose coupling between the chemical reaction and the mechanical event in the sliding machine. In this review, I will brie¯y describe a historical overview of the input±output problem in the molecular machines of living cells. Input±output in molecular machinesConsider a series of solid gears. The ratio of the angle of rotation of a gear in the input to the angle of rotation of another gear in the output is constant and independent of the speed of rotation or the torque for rotation. In such a way, are the input and output or in¯ux and ef¯ux in molecular machines of living cells tightly coupled? Does one chemical reaction in the input always generate a unit mechanical movement in the output?The molecular machines are very small, so that the input free energy is not much larger than the energy of thermal noise. Nevertheless, the machine is neither cooled nor isolated, but works at room temperature in water. The structural units of the machine, the protein molecules, are not rigid, but have thermal¯uctuation. The energy exchange among these units and their environment may be positively involved in the process of free energy conversion. The relation between input and output in the machine would not be straightforward. Intermediate processes in the machine would make the in¯ux±ef¯ux coupling loose. It is very likely that living cells invented the loose coupling mechanism in order to give an ef®cient conversion of small free energy in thermal noise.To understand the working principle of molecular machines, it is important to know, ®rst of all, their function. We have to de®ne their input and output, or in¯ux and ef¯ux, and carry out quantitative investigations on the relation between them under various conditions.

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“…For the fluctuating potential model, it is possible that some correlated agitations in the actomyosin system occur during or after the hydrolysis of ATP. In the presence of ATP, the bending motion of actin filaments was shown to enhance during the interaction with myosin, 14) indicating that the potential could be fluctuated with non-Gaussian fashion at the "active" states as assumed in this study. Recently, it has been also suggested that myosin V and VI, other myosin families working in non-muscle cells, 13),15),16) and a microtubule-based motor, kinesin 17) and its family 18) also move with biased Brownian motion.…”

mentioning

confidence: 91%

Model describing the biased Brownian movement of myosin.

Esaki

Ishii²,

Yanagida

2003

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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Introduction. Myosin is a biomolecular motor that is responsible for various types of cellular movement including muscle contraction and organelle transport. Movement is caused by the sliding movement of myosin molecules along actin filaments, fuelled by the chemical energy from adenosine tri-phosphate (ATP) hydrolysis. The fundamental problem of how this motor converts the chemical energy into the mechanical energy has yet to be elucidated. There are two major classes of models in terms of the relationship between the chemical reactions and the mechanical events. One class is the deterministic and mechanistic models, such as the lever armswinging model, where the movement of myosin along an actin filament is caused by a power stroke of the tail part of a myosin head acting as a lever arm, tightly coupled to the ATP hydrolysis. Fig. 1(a)): i) During the hydrolysis of a single ATP molecule the displacement of the myosin heads occurs in variable numbers (1-5) of 5.5 nm steps. The size of the individual steps corresponds to the distance between adjacent actin monomers in the actin filaments. This process is stochastic. ii) Steps also occasionally occur in the backward direction. Overall, the motion of myosin is preferentially directed to one end of the actin filament. iii) On applying a load to the myosin, the number of steps decreased and the dwell time Model describing the biased Brownian movement of myosinBy Seiji ESAKI, * ) Yoshiharu ISHII, ** ) and Toshio YANAGIDA * ), ** ), *** ), †) (Communicated by Fumio OOSAWA, M. J. A., Jan. 14, 2003) Abstract: A recent study with single molecule measurements has reported that myosin II, a molecular motor, generates stochastic and multiple steps during the hydrolysis of a single ATP molecule. In order to elucidate the mechanism for the motion of myosin, we traced the movements of individual molecules by simulating the Brownian movements along the potentials created by the interaction between a myosin molecule and an actin filament. We demonstrated that Brownian movement was biased to one direction as observed for myosins by either spatially tilting or temporally fluctuating the height of the potential. We incorporated the biased Brownian movement into an ATP hydrolysis reaction scheme and studied the effects of the load on the movement. The results could successfully explain the movements and mechanical properties of myosin. Thus, it was demonstrated that the movement of myosin is thermally driven and the random motion is biased by the energy released from the ATP hydrolysis.

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Direct observation of motion of single F-actin filaments in the presence of myosin

Cited by 468 publications

References 13 publications

Site-specific cation release drives actin filament severing by vertebrate cofilin

Site-specific cation release drives actin filament severing by vertebrate cofilin

The loose coupling mechanism in molecular machines of living cells

Model describing the biased Brownian movement of myosin.

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