Engineering the processive run length of myosin V
Engineering the processive run length of myosin V
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DOI：
10.1074/jbc.m703968200
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发表时间：
2007-09-14
影响因子：
4.8
通讯作者：
Trybus, Kathleen M.
中科院分区：
文献类型：
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作者：
Hodges, Alex R.;Krementsova, Elena B.;Trybus, Kathleen M.
与非进行性肌球蛋白相比，进行性运动肌球蛋白V在弱结合状态下对肌动蛋白具有高亲和力。在这里，我们测试是否这个功能是必不可少的肌球蛋白V走procedently沿着肌动蛋白丝。环2的净电荷，一个表面环牵连在肌球蛋白和肌动蛋白之间的初始弱结合，增加或减少相应地改变肌球蛋白V的亲和力肌动蛋白在弱结合状态，而不改变运动的速度。通过全内反射荧光显微镜测定单分子的过程运行长度。减少环2的净正电荷显着降低了肌动蛋白和进行性运行长度的肌球蛋白V的亲和力。相反，环2的正电荷增加肌动蛋白的亲和力和进行性运行长度。我们假设，高亲和力的肌动蛋白允许分离的头步进肌球蛋白V更快地找到它的下一个肌动蛋白结合位点，从而降低运行终止的概率。
The processive motor myosin V has a high affinity for actin in the weak binding states when compared with non-processive myosins. Here we test whether this feature is essential for myosin V to walk processively along an actin filament. The net charge of loop 2, a surface loop implicated in the initial weak binding between myosin and actin, was increased or decreased to correspondingly change the affinity of myosin V for actin in the weak binding state, without changing the velocity of movement. Processive run lengths of single molecules were determined by total internal reflection fluorescence microscopy. Reducing the net positive charge of loop 2 significantly decreased both the affinity of myosin V for actin and the processive run length. Conversely, the addition of positive charge to loop 2 increased actin affinity and processive run length. We hypothesize that a high affinity for actin allows the detached head of a stepping myosin V to find its next actin binding site more quickly, thus decreasing the probability of run termination.