通过大肠杆菌细胞外进行可调的力传导
Daniel P Williams-Jones1, Melissa N Webby1, Cara E Press1
1Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
概括
格拉姆阴性细菌使用质子动力 (PMF) 来驱动外膜过程. 这项研究揭示了PMF驱动的电机如何通过传感器蛋白产生机械力,这对于细菌外膜稳定性和营养进口至关重要.
科学领域:
- 细菌细胞外生物发生.
- 膜蛋白复合物 膜蛋白复合物
- 能量传导机制 能量传导机制
背景情况:
- 阴性细菌具有缺乏内在能量的外膜 (OM),因此需要内膜 (IM) 能量传导系统来进行OM过程.
- 托尔-帕尔和系统与质子驱动力 (PMF) 相结合,分别稳定了OM和进口营养素.
- 这两种系统都使用IM电机复合体 (与鞭毛状定位器Mot相同) 来通过IM蛋白 (TolA,TonB) 向OM转导力.
研究的目的:
- 阐明IM中的PMF驱动电机通过力传感器在OM产生机械工作的机制.
- 确定Tol-Pal系统中力传导的结构基础.
主要方法:
- 低温电子显微镜 (cryo-EM) 用于确定大肠杆菌TolQR电机复合物的4.3Å结构.
- 在体内测试中,使用模拟 TolA/TonB 蛋白质与交换或替换的周等离子体跨域来探测力转导机制.
- 在OM稳定和素进口中分析突变Tola蛋白的功能.
主要成果:
- 托尔QR运动复合体的冷-电磁结构显示出5:2的固体几何学,与相关的Ton和Mot复合体一致,支持旋转运动.
- 化学蛋白质测试表明,力转换器蛋白质的结构刚性,而不是特定的结构形式,是有效力转换的关键.
- 托拉突变体表现出不同的力输出,与它们稳定OM和导入胆素的能力相关.
结论:
- 该研究提供了对TolQR电机综合体的结构性见解,支持PMF驱动的力产生旋转机制.
- 旋转运动在OM中有效地转化为生理上相关的力,主要取决于像TolA这样的力转换器蛋白质的结构刚性.
- 这种机制对于细菌外膜的基本功能至关重要,包括稳定性和营养吸收.
相关概念视频
Transduction
20
Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome...
20
Stringent Response in E. coli
17
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
17
Chemotaxis in E. coli
23
Chemotaxis in Escherichia coli is a sensory-driven motility mechanism that enables bacteria to navigate chemical gradients, moving toward beneficial environments while avoiding harmful conditions. This process relies on a signal transduction system integrating external chemical cues with flagellar motor control.Chemoreceptors and Signal DetectionE. coli detects chemical gradients through methyl-accepting chemotaxis proteins (MCPs), which are membrane-bound chemoreceptors that sense attractants...
23
Tension Response at Adherens Junctions
2.7K
The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin...
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin...
2.7K
Cell-matrix's Response to Mechanical Forces
2.6K
In animal cells, the extracellular matrix allows cells within tissues to withstand external stresses and transmits signals from the outside of the cell to the inside. The extracellular matrix is extensive, and its composition varies between different types of tissues. For example, the reticular fibers and ground substance make up the ECM in loose connective tissue, while collagen and bone minerals make up the ECM of bone tissue.
Anchoring junctions mechanically attach a cell to the...
Anchoring junctions mechanically attach a cell to the...
2.6K
Global Regulatory Systems
28
Global regulatory systems in bacteria enable rapid and coordinated responses to environmental changes by integrating sensory inputs with gene expression, ensuring efficient adaptation to fluctuating conditions. Key global regulatory mechanisms include regulons, two-component systems, sigma factors, and secondary messengers.Regulons and Global RegulatorsA regulon is a collection of genes and operons controlled by a common global regulator. These regulators enable bacteria to prioritize resource...
28


