Non-equilibrium effect in the allosteric regulation of the bacterial flagellar switch
Non-equilibrium effect in the allosteric regulation of the bacterial flagellar switch
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DOI：
10.1038/nphys4081
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发表时间：
2017-03
期刊：
影响因子：
19.6
通讯作者：
Fangbin Wang;Hui Shi;Rui He;Renjie Wang;Rongjing Zhang;Junhua Yuan
中科院分区：
文献类型：
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作者：
Fangbin Wang;Hui Shi;Rui He;Renjie Wang;Rongjing Zhang;Junhua Yuan
鞭毛马达的切换机制为有鞭毛细菌的运动行为提供了基础。其高度敏感的响应先前已通过平衡模型来理解，无论是经典的两态协同变构模型，还是更普遍的伊辛型构象扩散模型。在这里，我们系统地研究了从高负载到零负载的各种负载条件下、不同质子动力 (pmf) 条件下以及不同扭矩产生单元（定子）数量下的电机切换。通过这样做，我们揭示了非平衡效应的特征。为了一致地解释电机开关对每种条件的依赖性，必须将以前被忽视的非平衡效应（电机扭矩的能量输入）纳入鞭毛开关的模型中。我们进一步表明这种效应增加了鞭毛开关的敏感性。利用鞭毛马达能量消耗的一小部分进行功能调节可以大大提高其灵敏度。预计在其他蛋白质复合物中也会发现类似的机制。
The switching mechanism of the flagellar motor provides the basis for the motile behaviour of flagellated bacteria. Its highly sensitive response has previously been understood in terms of equilibrium models, either the classical two-state concerted allosteric model, or more generally, the Ising-type conformation spread model. Here, we systematically study motor switching under various load conditions from high to zero load, under different proton motive force (pmf) conditions and varying the number of torque-generating units (stators). In doing so, we reveal the signature of a non-equilibrium effect. To consistently account for the motor-switching dependence on each those conditions, a previously neglected non-equilibrium effect—the energy input from the motor torque—has to be incorporated into models of the flagellar switch. We further show that this effect increases the sensitivity of the flagellar switch. Exploiting a very small fraction of the energy expense of the flagellar motor for functional regulation increases its sensitivity greatly. Similar mechanisms are expected to be found in other protein complexes.