Differential effects of the dynein-regulatory factor Lissencephaly-1 on processive dynein-dynactin motility
Differential effects of the dynein-regulatory factor Lissencephaly-1 on processive dynein-dynactin motility
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DOI：
10.1074/jbc.m117.790048
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发表时间：
2017-07-21
影响因子：
4.8
通讯作者：
McKenney, Richard J.
中科院分区：
文献类型：
--
作者：
Gutierrez, Pedro A.;Ackermann, Bryce E.;McKenney, Richard J.
细胞质动力蛋白是动物细胞中主要的负端定向微管运动蛋白，具有广泛的运动活性，包括囊泡货物、mrna、病毒和蛋白质的运输。Lissencephaly-1 （LIS1）是一种高度保守的动力蛋白调节因子，直接结合动力蛋白运动结构域，解耦动力蛋白的酶和机械循环，使动力蛋白在微管轨道上停滞。动力蛋白，另一种普遍存在的动力蛋白调节因子，从自抑制状态释放动力蛋白，导致快速、进行性动力蛋白运动的急剧增加。这些相反的活动是如何结合起来控制动力蛋白运动的尚不清楚。在这里，我们使用荧光单分子显微镜研究了LIS1与进程dyneindynactin-BicD2N （DDB）复合物的相互作用。令人惊讶的是，与仅在动力蛋白背景下建立的LIS1功能的流行模型相反，我们发现LIS1与DDB的结合不会强烈破坏过程运动性。运动DDB复合物与两个LIS1二聚体结合，突变分析表明，在DDB运动过程中，LIS1直接与动力蛋白运动结构域结合。有趣的是，与观察到的LIS1对分离动力蛋白运动的影响相反，LIS1以浓度依赖的方式增强了DDB速度。因此，LIS1对动力蛋白的运动具有浓度依赖性，并能与动力蛋白协同增强动力蛋白的运动。我们的研究结果表明，LIS1对动力蛋白运动的影响既取决于LIS1的浓度，也取决于其他调节因子如动力蛋白的存在，并可能为LIS1单倍体功能不足在无脑畸形神经发育障碍中的机制提供新的见解。
Cytoplasmic dynein is the primary minus-end-directed microtubule motor protein in animal cells, performing a wide range of motile activities, including transport of vesicular cargos, mRNAs, viruses, and proteins. Lissencephaly-1 (LIS1) is a highly conserved dynein-regulatory factor that binds directly to the dynein motor domain, uncoupling the enzymatic and mechanical cycles of the motor and stalling dynein on the microtubule track. Dynactin, another ubiquitous dynein-regulatory factor, releases dynein from an autoinhibited state, leading to a dramatic increase in fast, processive dynein motility. How these opposing activities are integrated to control dynein motility is unknown. Here, we used fluorescence single-molecule microscopy to study the interaction of LIS1 with the processive dyneindynactin-BicD2N (DDB) complex. Surprisingly, in contrast to the prevailing model for LIS1 function established in the context of dynein alone, we found that binding of LIS1 to DDB does not strongly disrupt processive motility. Motile DDB complexes bound up to two LIS1 dimers, and mutational analysis suggested that LIS1 binds directly to the dynein motor domains during DDB movement. Interestingly, LIS1 enhanced DDB velocity in a concentration-dependent manner, in contrast to observations of the effect of LIS1 on the motility of isolated dynein. Thus, LIS1 exerts concentration-dependent effects on dynein motility and can synergize with dynactin to enhance processive dynein movement. Our results suggest that the effect of LIS1 on dynein motility depends on both LIS1 concentration and the presence of other regulatory factors such as dynactin and may provide new insights into the mechanism of LIS1 haploinsufficiency in the neurodevelopmental disorder lissencephaly.