Temperature change does not affect force between regulated actin filaments and heavy meromyosin in single-molecule experiments

Masataka Kawai*, Takanori Kido, Martin Vogel, Rainer H A Fink, Shin'ichi Ishiwata

*この研究の対応する著者

    研究成果: Article査読

    30 被引用数 (Scopus)

    抄録

    The temperature dependence of sliding velocity, force and the number of cross-bridges was studied on regulated actin filaments (reconstituted thin filaments) when they were placed on heavy meromyosin (HMM) attached to a glass surface. The regulated actin filaments were used because our previous study on muscle fibres demonstrated that the temperature effect was much reduced in the absence of regulatory proteins. A fluorescently labelled thin filament was attached to the gelsolin-coated surface of a polystyrene bead. The bead was trapped by optical tweezers, and HMM-thin filament interaction was performed at 20-35°C to study the temperature dependence of force at the single-molecule level. Our experiments showed that there was a small increase in force with temperature (Q10 =1.43) and sliding velocity (Q10 =1.46). The small increase in force was correlated with the small increase in the number of cross-bridges (Q10 =1.49), and when force was divided by the number of cross-bridges, the result did not depend on the temperature (Q10 =1.03). These results demonstrate that the force each cross-bridge generates is fixed and independent of temperature. Our additional experiments demonstrate that tropomyosin (Tm) in the presence of troponin (Tn) and Ca2+ enhances both force and velocity, and a truncated mutant, Δ23Tm, diminishes force and velocity. These results are consistent with the hypothesis that Tm in the presence of Tn and Ca2+ exerts a positive allosteric effect on actin to make actomyosin linkage more secure so that larger forces can be generated.

    本文言語English
    ページ(範囲)877-887
    ページ数11
    ジャーナルJournal of Physiology
    574
    3
    DOI
    出版ステータスPublished - 2006 8

    ASJC Scopus subject areas

    • 生理学

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