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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Force-dependent polymorphism in type IV pili reveals hidden epitopes
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Force-dependent polymorphism in type IV pili reveals hidden epitopes

机译：IV型菌毛中力依赖性多态性揭示了隐藏的表位

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摘要

Through evolution, nature has produced exquisite nanometric structures, with features unrealized in the most advanced man-made devices. Type IV pili (Tfp) represent such a structure: 6-nm-wide retractable filamentous appendages found in many bacteria, including human pathogens. Whereas the structure of Neisseria gonorrhoeae Tfp has been defined by conventional structural techniques, it remains difficult to explain the wide spectrum of functions associated with Tfp. Here we uncover a previously undescribed force-induced quaternary structure of the N. gonorrhoeae Tfp. By using a combination of optical and magnetic tweezers, atomic force microscopy, and molecular combing to apply forces on purified Tfp, we demonstrate that Tfp subjected to approximately 100 pN of force will transition into a new conformation. The new structure is roughly 3 times longer and 40% narrower than the original structure. Upon release of the force, the Tfp fiber regains its original form, indicating a reversible transition. Equally important, we show that the force-induced conformation exposes hidden epitopes previously buried in the Tfp fiber. We postulate that this transition provides a means for N. gonorrhoeae to maintain attachment to its host while withstanding intermittent forces encountered in the environment. Our findings demonstrate the need to reassess our understanding of Tfp dynamics and functions. They could also explain the structural diversity of other helical polymers while presenting a unique mechanism for polymer elongation and exemplifying the extreme structural plasticity of biological polymers.
机译：通过进化，大自然产生了精美的纳米结构，其功能在最先进的人造设备中无法实现。 IV型菌毛（Tfp）代表这样的结构：在许多细菌（包括人类病原体）中发现了6纳米宽的可收缩丝状附件。尽管淋病奈瑟氏球菌Tfp的结构已通过常规结构技术定义，但仍然难以解释与Tfp有关的广泛功能。在这里，我们揭示了淋病奈瑟氏球菌Tfp先前未描述的力诱导的四级结构。通过结合使用光镊和磁镊，原子力显微镜和分子梳将力施加到纯化的Tfp上，我们证明了受到约100 pN力作用的Tfp将转变为新的构象。新结构的长度约为原始结构的3倍，而宽度则缩小40％。释放力后，Tfp纤维恢复其原始形式，表明可逆转变。同样重要的是，我们表明力诱导的构象暴露了先前埋在Tfp纤维中的隐藏表位。我们推测，这种转变为淋病奈瑟菌提供了一种维持其宿主附着力的方法，同时还能承受环境中遇到的间歇性力量。我们的发现表明有必要重新评估我们对Tfp动力学和功能的理解。他们还可以解释其他螺旋聚合物的结构多样性，同时提出独特的聚合物伸长机理，并举例说明生物聚合物的极端结构可塑性。

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