Dictyostelium myosin-5b is a conditional processive motor
Dictyostelium myosin-5b is a conditional processive motor
复制标题
DOI：
10.1074/jbc.m802957200
复制
发表时间：
2008-10-03
影响因子：
4.8
通讯作者：
Tsiavaliaris, Georgios
中科院分区：
文献类型：
--
作者：
Taft, Manuel H.;Hartmann, Falk K.;Tsiavaliaris, Georgios
网骨藻肌球蛋白-5b是myoJ的基因产物，也是盘状网骨藻中产生的两种密切相关的肌球蛋白-5同工酶之一。在这里，我们报告的蛋白质的动力学和功能特性的详细调查。在标准测定缓冲液条件下，网囊藻肌球蛋白-5b在ADP存在下表现出高肌动蛋白亲和力、快速ATP水解，以及在肌动蛋白存在下表现出高稳态ATP酶活性，其速率受ADP释放限制。这些特性对于能够沿着沿着肌动蛋白丝长距离运动而不解离的进行性马达来说是典型的。我们的研究结果表明，游离镁离子的浓度的生理减少导致ADP释放的速率增加和缩短的时间分数的电机花费在强肌动蛋白结合状态。一致的是，电机的能力，有效地易位肌动蛋白丝在非常低的表面密度降低浓度的游离Mg 2+离子。此外，我们提供的证据表明，所观察到的Ddmyosin-5 b运动活性的变化是生理相关性，并提出了一种机制，通过这种分子马达可以进行性和非进行性运动之间切换。
Dictyostelium myosin-5b is the gene product of myoJ and one of two closely related myosin-5 isoenzymes produced in Dictyostelium discoideum. Here we report a detailed investigation of the kinetic and functional properties of the protein. In standard assay buffer conditions, Dictyostelium myosin-5b displays high actin affinity in the presence of ADP, fast ATP hydrolysis, and a high steady-state ATPase activity in the presence of actin that is rate limited by ADP release. These properties are typical for a processive motor that can move over long distances along actin filaments without dissociating. Our results show that a physiological decrease in the concentration of free Mg2+-ions leads to an increased rate of ADP release and shortening of the fraction of time the motor spends in the strong actin binding states. Consistently, the ability of the motor to efficiently translocate actin filaments at very low surface densities decreases with decreasing concentrations of free Mg2+-ions. In addition, we provide evidence that the observed changes in Ddmyosin-5b motor activity are of physiological relevance and propose a mechanism by which this molecular motor can switch between processive and non-processive movement.