Dynamic Property of F-Actin and Thin Filament

Oosawa, Fumio; Fujime, Satoru; Ishiwata, Shin’ichi; Mihashi, Koshin

doi:10.1101/sqb.1973.037.01.038

Cited by 95 publications

(55 citation statements)

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“…Myosin has been shown to induce cooperative conformational changes within actin filaments (10,38), including cooperative restriction of the mobility of the actin subunits by strongly bound myosin heads (22). In addition, myosin II heads bind to actin filaments in a cooperative manner (27,39), indicating that cooperative conformational changes induced by the binding of the first myosin head to one actin subunit accelerate binding of other myosin heads to neighboring actin subunits.…”

Section: Discussionmentioning

confidence: 99%

G146V Mutation at the Hinge Region of Actin Reveals a Myosin Class-specific Requirement of Actin Conformations for Motility

Noguchi

Komori

Umeki

et al. 2012

Journal of Biological Chemistry

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Background:The roles of conformational changes of actin in myosin motility are unclear. Results: A G146V mutation in actin, which perturbed its conformation, impaired force generation by myosin II, but not by myosin V. Conclusion: Conformational changes of actin involving Gly-146 have critical roles in motility of myosin II, but not of myosin V. Significance: The mechanism of motility may be different between myosin types.

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Section: Discussionmentioning

confidence: 99%

G146V Mutation at the Hinge Region of Actin Reveals a Myosin Class-specific Requirement of Actin Conformations for Motility

Noguchi

Komori

Umeki

et al. 2012

Journal of Biological Chemistry

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“…Signals that are sensitive to local conformational changes were usually reported to give a unidirectional response which was a linear function of the fraction of actin monomers bound [15,31,62,[72][73][74], although cooperative (non-linear) effects were also reported [6, 611 and other authors observed a biphasic change in ultraviolet absorption [75] and fluorescence intensity of static fluorescence anisotropy of etheno-ADP in F-actin [31,76]. Probes reporting the rotational mobility of F-actin give a cooperative response [4,6,11,12,15,771 (and this work), usually unidirectional, but a biphasic response was observed in the quasi-elastic light-scattering [4, 61. As we show here, the character of the response may change depending on the time of actin polymerization.…”

Section: Discussionmentioning

confidence: 99%

An EPR study of the rotational dynamics of actins from striated and smooth muscle and their complexes with heavy meromyosin

Mossakowska

Belágyi

Strzelecka‐Gołaszewska

1988

European Journal of Biochemistry

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The rotational motions of the actin from rabbit skeletal muscle and from chicken gizzard smooth muscle were measured by conventional and saturation transfer electron paramagnetic resonance (EPR) spectroscopy using maleimide spin-label rigidly bound at Cys-374. The conventional EPR spectra indicate a slight difference in the polarity of the environment of the label and in the rotational mobility of the monomeric gizzard actin compared to its skeletal muscle counterpart. These differences disappear upon polymerization. The EPR spectra of the two actins in their F form and in their complexes with heavy meromyosin (HMM) did not reveal any difference in the rotational dynamic properties that might be correlated with the known differences in the activation of myosin ATPase activity by smooth and skeletal muscle actin.Our results agree with earlier EPR studies on skeletal muscle actin in showing that polymerization stops the nanosecond rotational motion of actin monomers and that F-actin undergoes rotational motion having an effective correlation time of the order of 0.1 ms. However, our measurements show that complete elimination of the nanosecond motions requires prolonged incubation of F-actin, suggesting that the slow formation of interfilamental cross-links in concentrated F-actin solutions contributes to this process.We have also used the EPR spectroscopy to study the interaction between HMM and actin in the F and G form. Our results show that in the absence of salt one HMM molecule can cooperatively interact with eight monomers to produce a polymer which closely resembles F-actin in its rotational mobility but differs from the complex of F-actin with HMM. The results indicate that salt is necessary for further slowing down, in a cooperative manner, the sub-millisecond internal motion in actin polymer and for a non-cooperative change in the intramonomer conformation around Cys-374 on the binding of HMM.

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“…Molecular transitions had first been noted in the 1960s and 1970s [66][67][68]. On exposure to myosin, actin monomers underwent a 10°r otation [69].…”

Section: Muscle Contractionmentioning

confidence: 99%

Is the Cell a Gel-and Why Does It Matter?

Pollack

2001

JJP

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It has been long recognized that the cytoplasm is a gel, even before the classic book by Frey-Wyssling [1]. Textbooks continue to emphasize the cytoplasm's gel-like consistency, and several groups have recently gone on to describe the functional relevance of the gel-sol transition [2,3]. Researchers working on actin filaments in particular have focused on the cytoplasm's gel-like behavior [4], as have some groups concerned with cellular metabolism [5]. There can be little doubt that the cytoplasm has the consistency of a gel.Yet virtually all cell biological mechanisms build on the principle of free diffusion in aqueous solution. One merely needs to examine representative mechanistic pathways to note the many diffusional steps required in proceeding from stimulus to action. These steps invariably include: ions diffusing into and out of channels; ions diffusing into and out of pumps; ions diffusing through the cytoplasm; proteins diffusing toward other proteins; and substrates diffusing toward enzymes. A cascade of multiple diffusional steps underlies nearly every intracellular process-notwithstanding the cytoplasm's character as a gel, where diffusion can be extremely slow.Surrounding this aqueous intracellular "solution" is the impermeant cell membrane, which restricts the passage of ions and other solutes to flow largely through an array of channels and pumps. Well over 100 solute-specific channels have been identified, with new ones emerging regularly. The same goes for pumps: Since ion concentrations inside and outside the cell are rarely in electrochemical equilibrium, the observed intracellular concentrations are maintained by active pumping. For pump and channel systems to operate, ions require free access.These concepts are certainly familiar to most readers of this journal. For others, the text by Alberts et al.[6] provides a detailed review of this foundational paradigm-along with the manner in which this paradigm accounts for basic cell function. Key words: phase-transition, polymer gel, cell, structured water, cooperativity, movement.Abstract: That the cell is a gel is broadly acknowledged. Textbooks begin with this assertion-and then proceed with great abandon to derive mechanisms based on free diffusion, as though the gel concept were groundless and cell was an aqueous solution. This disconnect emerges in part because the behavior of gels is not well understood, particularly among most biologists. Recently, great strides have been made in the understanding of gel behavior. It has become clear, for example, that a central mechanism in gel function is the phase-transition-a qualitative structural change prompted by a subtle change of environment, not unlike the transition from ice to water. Phase-transitions are capable of doing work. If the cell is a gel, then a logical approach to understanding cell function is to understand gel function-especially whether some role may be played by the phase-transition. Here we pursue this approach. We first consider the dichotomy of the cell as a gel and the cell...

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Dynamic Property of F-Actin and Thin Filament

Cited by 95 publications

References 0 publications

G146V Mutation at the Hinge Region of Actin Reveals a Myosin Class-specific Requirement of Actin Conformations for Motility

G146V Mutation at the Hinge Region of Actin Reveals a Myosin Class-specific Requirement of Actin Conformations for Motility

An EPR study of the rotational dynamics of actins from striated and smooth muscle and their complexes with heavy meromyosin

Is the Cell a Gel-and Why Does It Matter?

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