Sliding movement of single actin filaments on one-headed myosin filaments

Harada, Yoshie; Noguchi, Akira; Kishino, Akiyoshi; Yanagida, Toshio

doi:10.1038/326805a0

Cited by 304 publications

(173 citation statements)

References 17 publications

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“…3A), and myosin sometimes dissociated from the actin filament. These results are consistent with the in vitro motility assay (29) and highlight the critical role of the electrostatic interaction. The reason for the loss of motility is now clearly understood on the basis of the energy landscape (Fig.…”

Section: Resultssupporting

confidence: 80%

Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor

Takano

Terada

Sasai

2010

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

120

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The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction, converting chemical energy into mechanical work. Although recent single molecule and structural studies have shed new light on the energy-converting mechanism, the physical basis of the molecular-level mechanism remains unclear because of the experimental limitations. To provide a clue to resolve the controversy between the lever-arm mechanism and the Brownian ratchet-like mechanism, we here report an in silico single molecule experiment of an actomyosin motor. When we placed myosin on an actin filament and allowed myosin to move along the filament, we found that myosin exhibits a unidirectional Brownian motion along the filament. This unidirectionality was found to arise from the combination of a nonequilibrium condition realized by coupling to the ATP hydrolysis and a ratchet-like energy landscape inherent in the actin-myosin interaction along the filament, indicating that a Brownian ratchet-like mechanism contributes substantially to the energy conversion of this molecular motor. M olecular machines in living organisms are nanometer-sized small systems working robustly and efficiently in the presence of the severely disturbing thermal noises. Furthermore, in the case of the molecular motors, the energy supplied by the hydrolysis of adenosine triphosphate (ATP), which is to be converted to the mechanical work, is only an order of magnitude larger than the thermal energy at room temperature (∼20k B T), and hence it seems likely that the molecular machines harness the thermal noise, instead of suppressing it as the human-made machines do (1). This distinct feature of the molecular machines should arise from the atomic structures of the constituent proteins, which is reflected in the current focus of interest in the structural aspect of the molecular machines. However, it should be remembered that the structural aspect is not everything but is inseparably linked to the dynamical and energetical aspects. Therefore, a unified description of structure, dynamics, and energetics is the step necessary to understand the molecular-level physical principle of how the molecular machines work.The actomyosin molecular motor, the system composed of myosin II and actin molecules, is responsible for muscle contraction, and is the most extensively studied molecular motor. It has been shown by single molecule experiments (SME) that a single myosin molecule and an actin filament (polymerized actin) constitute the minimal force-generating unit of this motor (2-4) (see Fig. 1A). Although SME has been a powerful approach to study the dynamical aspect of the force-generating unit (2-4), the limitation of the spatiotemporal resolution of SME has inhibited us from developing the full atomistic picture of the force-generating process. On the other hand, since the currently available high-resolution structures of myosin (5-7) are those obtained in the crystalline environment and in the absence of actin, it remains unc...

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Section: Resultssupporting

confidence: 80%

Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor

Takano

Terada

Sasai

2010

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

120

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“…It is known, for example, that the affinity of single-headed myosin for actin is about an order of magnitude lower than that of double-headed myosin (1). However, in vitro motility assays have shown that single-headed myosin II molecules (2,3) and single isolated myosin heads (4,5) are able to produce force and movement, indicating that any cooperative aspect is not essential for function. An alternate possibility is that the dimeric structure of myosin is required solely to generate an a-helical coiled-coil tail.…”

mentioning

confidence: 99%

Single-headed myosin II acts as a dominant negative mutation in Dictyostelium.

Burns

Larochelle

Erickson

et al. 1995

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

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Conventional myosin II is an essential protein for cytokinesis, capping of cell surface receptors, and development of Dictyostelium cells. Myosin II also plays an important role in the polarization and movement of cells. All conventional myosins are double-headed molecules but the significance of this structure is not understood since singleheaded myosin II can produce movement and force in vitro. We found that expression of the tail portion of myosin II in Dictyostelium led to the formation of single-headed myosin II in vivo. The resultant cells contain an approximately equal ratio of double-and single-headed myosin II molecules. Surprisingly, these cells were completely blocked in cytokinesis and capping of concanavalin A receptors although development into fruiting bodies was not impaired. We found that this phenotype is not due to defects in myosin light chain phosphorylation. These results show that single-headed myosin II cannot function properly in vivo and that it acts as a dominant negative mutation for myosin II function. These results suggest the possibility that cooperativity of myosin II heads is critical for force production in vivo.

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“…Rhodamine-phalloidin binds to actin filaments assembled in Mg > and KC1 with a I:1 stoichiometry and a dissociation equilibrium constant of 10 20 nM [15], and phalloidin itself appears to have a 5-to 10-fold higher affinity [23]. Rhodamine phalloidin is commonly used to label actin-containing filaments in cells and extracts of cells, and actin filaments labelled with the fluorescent deriwttive of phalloidin, tetramethyl rhodamine-phalloidin, can move on tethered myosin in in vitro motility assays [18,24]. It has been proposed that hydrolysis of ATP on filamentous actin might be an essential step in the mechanism of chemo-mechanical transduction in contracting muscle fibers [3,4,11,12].…”

Section: Discussionmentioning

confidence: 99%

The effect on actin ATPase of phalloidin and tetramethylrhodamine phalloidin

Пинаев¹,

Schutt²,

Lindberg³

1995

FEBS Letters

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Actin polymerization has been studied in the absence of excess nucleotide. Using G-actin ATP monomers, it was shown that mechanical shearing stimulates ATP hydrolysis. The procedures used enabled the detection of differential effects of phalloidin and tetramethylrhodamine-phalloidin, on the Prrelease step of the actin ATPase. It is concluded that tetramethylrhodamine, in contrast to phaHoidin, accelerates Prrelease from actin filaments.

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Sliding movement of single actin filaments on one-headed myosin filaments

Cited by 304 publications

References 17 publications

Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor

Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor

Single-headed myosin II acts as a dominant negative mutation in Dictyostelium.

The effect on actin ATPase of phalloidin and tetramethylrhodamine phalloidin

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