Tunable force transduction through the Escherichia coli cell envelope.
Tunable force transduction through the Escherichia coli cell envelope.
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DOI：
10.1073/pnas.2306707120
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发表时间：
2023-11-21
影响因子：
11.1
通讯作者：
Kleanthous, Colin
中科院分区：
文献类型：
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作者：
Williams-Jones, Daniel P.;Webby, Melissa N.;Press, Cara E.;Gradon, Jan M.;Armstrong, Sophie R.;Szczepaniak, Joanna;Kleanthous, Colin
革兰氏阴性菌的外膜（OM）是引起耐药危机的主要因素。Tol系统是一个保守的组件，利用充能的内膜来稳定这些细菌的OM。系统缺陷导致OM不稳定和抗生素敏感性增加。我们报告了Tol电机复合体的结构，与其他电机相比，它支持旋转作为产生力的手段。我们还证明，通过改变连接两层膜的力传导蛋白的结构，可以改变来自马达的稳定机械力的程度。革兰氏阴性菌的外膜（OM）没有能量，因此需要驱动力的过程必须连接到内膜（IM）的能量转导系统。Tol （toll - pal）和Ton是相互关联的质子动力- (PMF-)耦合组件，分别稳定OM和进口必需营养素。两者都依赖于质子收集的IM马达（定子）复合物，它们是鞭毛定子单元Mot的同源物，分别通过细长的IM力传感器蛋白TolA和TonB将力传递给OM。IM中的pmf驱动电机如何通过力传感器在OM产生机械功尚不清楚。在这里，使用低温电子显微镜，我们报告了大肠杆菌TolQR马达复合物的4.3Å结构。该结构重申了在Ton和Mot中看到的5:2的化学计量，并且运动亚基彼此旋转10到16°，支持旋转运动作为这些配合物的默认值。我们通过嵌合TolA/TonB蛋白的体内实验，探索了力传递到OM的机制，其中其结构分歧的部分被交换或替换为本质上无序的序列。我们发现TolA突变体表现出一系列的力输出，这反映在它们各自稳定OM和通过OM输入细胞毒性粘菌素的能力上。我们的研究表明，力传感器蛋白的结构刚性，而不是任何特定的结构形式，驱动pmf驱动的5:2运动复合物的旋转运动有效地转化为OM的生理相关力。
The outer membrane (OM) of Gram-negative bacteria is a major factor in the antimicrobial resistance crisis. The Tol system is a conserved assembly that exploits the energised inner membrane to stabilise the OM of these bacteria. System defects result in a destabilised OM and increased antibiotic susceptibility. We report the structure of the Tol motor complex, which, by comparison to other motors, supports rotation as the means of force generation. We also demonstrate that the degree of stabilising mechanical force from the motor can be modified by varying the structure of the force-transducing protein that connects the two membranes. The outer membrane (OM) of Gram-negative bacteria is not energised and so processes requiring a driving force must connect to energy-transduction systems in the inner membrane (IM). Tol (Tol-Pal) and Ton are related, proton motive force- (PMF-) coupled assemblies that stabilise the OM and import essential nutrients, respectively. Both rely on proton-harvesting IM motor (stator) complexes, which are homologues of the flagellar stator unit Mot, to transduce force to the OM through elongated IM force transducer proteins, TolA and TonB, respectively. How PMF-driven motors in the IM generate mechanical work at the OM via force transducers is unknown. Here, using cryoelectron microscopy, we report the 4.3Å structure of the Escherichia coli TolQR motor complex. The structure reaffirms the 5:2 stoichiometry seen in Ton and Mot and, with motor subunits related to each other by 10 to 16° rotation, supports rotary motion as the default for these complexes. We probed the mechanism of force transduction to the OM through in vivo assays of chimeric TolA/TonB proteins where sections of their structurally divergent, periplasm-spanning domains were swapped or replaced by an intrinsically disordered sequence. We find that TolA mutants exhibit a spectrum of force output, which is reflected in their respective abilities to both stabilise the OM and import cytotoxic colicins across the OM. Our studies demonstrate that structural rigidity of force transducer proteins, rather than any particular structural form, drives the efficient conversion of PMF-driven rotary motions of 5:2 motor complexes into physiologically relevant force at the OM.
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影响因子：
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