突变细菌脂多糖（LPS-Ra）表面层之间的相互作用：表面囊泡，膜融合以及Ca2 +和温度的影响。,Langmuir

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突变细菌脂多糖（LPS-Ra）表面层之间的相互作用：表面囊泡，膜融合以及Ca2 +和温度的影响。
Langmuir ( IF 3.7 ) Pub Date : 2019-10-24 , DOI: 10.1021/acs.langmuir.9b02609
Christian Redeker ₁ , Wuge H Briscoe ₁

Affiliation

脂多糖（LPS）是革兰氏阴性细菌保护性外膜的主要成分。理解溶液条件如何影响含LPS的膜对于优化抗菌剂（ABA）的设计非常重要，这些ABA利用静电和疏水相互作用来破坏细菌膜。在这里，已经使用表面力装置（SFA）研究了水介质中LPS（Ra突变体）的表面层之间的相互作用，探讨了温度和二价Ca ²⁺的影响。阳离子。互补动态光散射（DLS）表征表明，LPS-Ra在水性介质中形成直径约为28-80 nm的囊状聚集体。SFA结果表明，在室温（RT）下，LPS-Ra囊泡在纯水中微弱地吸附到云母上，并且当两个表面彼此接近时，表面层很容易被挤出。但是，在室温下以接近生理浓度（2.5 mM）添加钙（Ca ²⁺）阳离子时，会观察到LPS多层或云母上的LPS脂质体变形，这可能是由于LPS磷酸基团之间以及LPS磷酸酯和带负电的云母之间的桥接由Ca ²⁺介导，在表面分离D ₀处有硬壁排斥约30–40 nm。在40℃，这是上面的LPS镭β-α酰基链熔融温度（Ť_米= 36℃），可以观察到在压缩下的表面层之间的融合事件，显而易见δ d〜8-10纳米步骤在归因于LPS-双层的力-距离曲线被挤出由于LPS酰基链的流动性增强，具有最终的硬壁面分离d ₀对应于单个双层的限制之间的厚度〜8-10纳米表面。这些空前的SFA结果揭示了LPS表面层对温度和Ca ^2+的复杂结构响应，这暗示着我们对细菌膜的结构和相互作用有基本的了解。

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Interactions between Mutant Bacterial Lipopolysaccharide (LPS-Ra) Surface Layers: Surface Vesicles, Membrane Fusion, and Effect of Ca2+and Temperature.

Lipopolysaccharides (LPS) are a major component of the protective outer membrane of Gram-negative bacteria. Understanding how the solution conditions may affect LPS-containing membranes is important to optimizing the design of antibacterial agents (ABAs) which exploit electrostatic and hydrophobic interactions to disrupt the bacteria membrane. Here, interactions between surface layers of LPS (Ra mutants) in aqueous media have been studied using a surface force apparatus (SFA), exploring the effects of temperature and divalent Ca²⁺ cations. Complementary dynamic light scattering (DLS) characterization suggests that vesicle-like aggregates of diameter ∼28–80 nm are formed by LPS-Ra in aqueous media. SFA results show that LPS-Ra vesicles adsorb weakly onto mica in pure water at room temperature (RT) and the surface layers are readily squeezed out as the two surfaces approach each other. However, upon addition of calcium (Ca²⁺) cations at near physiological concentration (2.5 mM) at RT, LPS multilayers or deformed LPS liposomes on mica are observed, presumably due to bridging between LPS phosphate groups and between LPS phosphates and negatively charged mica mediated by Ca²⁺, with a hard wall repulsion at surface separation D₀ ∼ 30–40 nm. At 40 °C, which is above the LPS-Ra β–α acyl chain melting temperature (T_m = 36 °C), fusion events between the surface layers under compression could be observed, evident from δD ∼ 8–10 nm steps in the force–distance profiles attributed to LPS-bilayers being squeezed out due to enhanced fluidity of the LPS acyl-chain, with a final hard wall surface separation D₀ ∼ 8–10 nm corresponding to the thickness of a single bilayer confined between the surfaces. These unprecedented SFA results reveal intricate structural responses of LPS surface layers to temperature and Ca²⁺, with implications to our fundamental understanding of the structures and interactions of bacterial membranes.

更新日期：2019-10-25

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