Motor-Substrate Interactions in Mycoplasma Motility Explains Non-Arrhenius Temperature Dependence
Motor-Substrate Interactions in Mycoplasma Motility Explains Non-Arrhenius Temperature Dependence
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DOI：
10.1016/j.bpj.2009.09.020
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发表时间：
2009-12-02
影响因子：
3.4
通讯作者：
Oster, George
中科院分区：
文献类型：
--
作者：
Chen, Jing;Neu, John;Oster, George
支原体表现出一种新的，底物依赖性的滑行运动，是由类似的400“腿”蛋白驱动。腿与基底相互作用并传递由ATP酶马达组件产生的力。在10-40摄氏度的狭窄温度范围内，电池的速度线性增加近10倍。这对应于从在10摄氏度时近似于45 k（B）达特减小到在40摄氏度时近似于10 k（B）T的阿克里米乌斯因子。另一方面，在不同温度下的载荷-速度曲线外推到几乎相同的失速力，这表明在失速附近的温度不敏感的力产生机制。在这篇文章中，我们提出了一个腿基板相互作用机制，解释了有趣的温度敏感性，这种运动。在低温下的大的Arrhenius因子来自于在腿蛋白的远端处的许多底物结合位点产生的许多较小的能量势垒的添加。由于两个因素，Arabius依赖性在高温下减弱：1）多位点结合机制固有的能量势垒的有效多重性降低;和2）温度敏感的弱易化腿释放，其缩短了动力冲程。该模型提出了一个解释类似的陡峭，亚Arrhenius温度-速度曲线中观察到的许多分子马达，如驱动蛋白和肌球蛋白，其中的温度行为是占主导地位的催化生物化学，但由电机基板的相互作用。
Mycoplasmas exhibit a novel, substrate-dependent gliding motility that is driven by similar to 400 "leg" proteins. The legs interact with the substrate and transmit the forces generated by an assembly of ATPase motors. The velocity of the cell increases linearly by nearly 10-fold over a narrow temperature range of 10-40 degrees C. This corresponds to an Arrhenius factor that decreases from similar to 45 k(B) Tat 10 degrees C to similar to 10 k(B) T at 40 degrees C. On the other hand, load-velocity curves at different temperatures extrapolate to nearly the same stall force, suggesting a temperature-insensitive force-generation mechanism near stall. In this article, we propose a leg-substrate interaction mechanism that explains the intriguing temperature sensitivity of this motility. The large Arrhenius factor at low temperature comes about from the addition of many smaller energy barriers arising from many substrate-binding sites at the distal end of the leg protein. The Arrhenius dependence attenuates at high temperature due to two factors: 1), the reduced effective multiplicity of energy barriers intrinsic to the multiple-site binding mechanism; and 2), the temperature-sensitive weakly facilitated leg release that curtails the power stroke. The model suggests an explanation for the similar steep, sub-Arrhenius temperature-velocity curves observed in many molecular motors, such as kinesin and myosin, wherein the temperature behavior is dominated not by the catalytic biochemistry, but by the motor-substrate interaction.