Cross-Correlated TIRF/AFM Reveals Asymmetric Distribution of Force-Generating Heads along Self-Assembled, "Synthetic" Myosin Filaments
Cross-Correlated TIRF/AFM Reveals Asymmetric Distribution of Force-Generating Heads along Self-Assembled, "Synthetic" Myosin Filaments
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DOI：
10.1016/j.bpj.2008.11.032
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发表时间：
2009-03-04
影响因子：
3.4
通讯作者：
Discher, Dennis E.
中科院分区：
文献类型：
--
作者：
Brown, Andre E. X.;Hategan, Alina;Discher, Dennis E.
肌球蛋白-II的杆状尾部驱动具有头部排列的细丝组装，该头部排列通常被认为是对称的双极，其对肌动蛋白产生相等且相反的收缩力。自组装肌球蛋白丝在这里显示为不对称的生理缓冲液的基础上互相关的图像从原子力显微镜和全内反射荧光。这些正交方法的定量互相关产生的结构信息不能单独用于任一种方法，表明荧光强度沿着细丝长度与高度成比例。这意味着肌球蛋白头在肌丝轴周围形成一个壳，与F-肌动蛋白结合一致。进一步估计类似于50-100头/微米的电机密度，但是与另一半相比，任何给定灯丝的一半上的电机平均多32%，而与长度无关。一个纯粹的熵金字塔晶格模型的开发和映射到戴克路径问题，定性地捕捉这种缺乏长度依赖性和分布的细丝不对称性。这种强烈不对称的双极;可能在细胞和肌动蛋白-肌球蛋白凝胶中产生不平衡的收缩力，从而有助于运动以及细胞骨架张力。
Myosin-II's rod-like tail drives filament assembly with a head arrangement that is often considered to be a symmetric bipole that generates equal and opposite contractile forces on actin. Self-assembled myosin filaments are shown here to be asymmetric in physiological buffer based on cross-correlated images from both atomic force microscopy and total internal reflection fluorescence. Quantitative cross-correlation of these orthogonal methods produces structural information unavailable to either method alone in showing that fluorescence intensity along the filament length is proportional to height. This implies that myosin heads form a shell around the filament axis, consistent with F-actin binding. A motor density of similar to 50-100 heads/micrometer is further estimated but with an average of 32% more motors on one half of any given filament compared to the other, regardless of length. A purely entropic pyramidal lattice model is developed and mapped onto the Dyck paths problem that qualitatively captures this lack of length dependence and the distribution of filament asymmetries. Such strongly asymmetric bipoles; are likely to produce an unbalanced contractile force in cells and in actin-myosin gels and thereby contribute to motility as well as cytoskeletal tension.