The reciprocal coordination and mechanics of molecular motors in living cells
The reciprocal coordination and mechanics of molecular motors in living cells
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DOI：
10.1073/pnas.0809849106
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发表时间：
2009-03-03
影响因子：
11.1
通讯作者：
Guilford, William H.
中科院分区：
文献类型：
--
作者：
Laib, Jeneva A.;Marin, John A.;Guilford, William H.
活细胞中的分子马达参与整个细胞的运动、收缩、发育形状的改变以及细胞器的运动和定位。不同方向性的马达在细胞中是功能协调还是在半随机的“拔河”中运作尚不清楚。我们在这里表明，衣藻鞭毛中基于微管的顺行和逆行马达是受调节的，因此在任何单一时间只有共同方向的马达参与。用激光诱捕器在固定化瘫痪鞭毛衣单胞菌的质膜上定位微球。当微管马达与跨膜蛋白FMG-1结合时，用纳米分辨率测量了微球的顺行和逆行运动。平均有10个马达使微球向两个方向移动。在运输过程中，方向反转是不常见的，每一次运输事件都有静止期，这表明只有一种运动类型的协调和排他性作用。当温度升高到32℃后，运动蛋白-2 （fla10）的温度敏感突变体只表现出逆行运输事件，平均由7个马达驱动。这些数据表明，活细胞中的分子马达可以相互协调，以大量同时参与，并在一个方向上进行排他运输，即使存在混合的马达群体。这为在活的细胞内环境中研究分子马达的力学、调节和定向协调提供了一个独特的模型。
Molecular motors in living cells are involved in whole-cell locomotion, contractility, developmental shape changes, and organelle movement and positioning. Whether motors of different directionality are functionally coordinated in cells or operate in a semirandom "tug of war'' is unclear. We show here that anterograde and retrograde microtubule-based motors in the flagella of Chlamydomonas are regulated such that only motors of a common directionality are engaged at any single time. A laser trap was used to position microspheres on the plasma membrane of immobilized paralyzed Chlamydomonas flagella. The anterograde and retrograde movements of the microsphere were measured with nanometer resolution as microtubule-based motors engaged the transmembrane protein FMG-1. An average of 10 motors acted to move the microsphere in either direction. Reversal of direction during a transport event was uncommon, and quiescent periods separated every transport event, suggesting the coordinated and exclusive action of only a single motor type. After a jump to 32 degrees C, temperature-sensitive mutants of kinesin-2 (fla10) showed exclusively retrograde transport events, driven by 7 motors on average. These data suggest that molecular motors in living cells can be reciprocally coordinated to engage simultaneously in large numbers and for exclusive transport in a single direction, even when a mixed population of motors is present. This offers a unique model for studying the mechanics, regulation, and directional coordination of molecular motors in a living intracellular environment.