Periodicity in Attachment Organelle Revealed by Electron Cryotomography Suggests Conformational Changes in Gliding Mechanism of Mycoplasma pneumoniae.
Periodicity in Attachment Organelle Revealed by Electron Cryotomography Suggests Conformational Changes in Gliding Mechanism of Mycoplasma pneumoniae.
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DOI：
10.1128/mbio.00243-16
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发表时间：
2016-04-12
期刊：
影响因子：
6.4
通讯作者：
Miyata M
中科院分区：
文献类型：
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作者：
Kawamoto A;Matsuo L;Kato T;Yamamoto H;Namba K;Miyata M
肺炎支原体是一种致病菌，它以独特的机制在宿主表面滑行。它在细胞极形成一个附着细胞器，作为一个突起，由球形表面结构和内核组成。在这里，我们详细分析了三维结构的细胞器的电子冷冻断层扫描。在表面上，球形颗粒形成了一个二维阵列，尽管规则性有限。使用非结合突变体和抗体的分析表明，knoblike颗粒对应于napike结构，已被观察到的负染色电子显微镜，很可能是作为一个复杂的P1粘附素，结合和滑行的关键蛋白质形成。成对的薄板和厚板分别具有刚性的六边形晶格和具有高度可变的重复距离的条纹。可变和不变的结构在内部的核心和P1粘附素阵列的表面上的组合建议的模型中，轴向延伸和压缩的厚板沿着刚性薄板耦合与附件和从基板上分离在滑行。人支原体肺炎是由肺炎支原体（Mycoplasma pneumoniae）引起的一种病原菌，近年来在世界范围内流行。这种微小的细菌，细胞体长约2微米，在人体气管表面滑动，通过与唾液酸化寡糖结合感染宿主，唾液酸化寡糖也是流感病毒的结合靶点。支原体滑行运动的机制与其他研究充分的运动系统无关，如细菌鞭毛和细胞质马达蛋白。在这里，我们可视化的附着细胞器，细胞结构的滑翔，三维使用电子冷冻断层扫描和其他传统的方法。根据建筑图像，提出了一种可能的滑动机制。
Mycoplasma pneumoniae, a pathogenic bacterium, glides on host surfaces using a unique mechanism. It forms an attachment organelle at a cell pole as a protrusion comprised of knoblike surface structures and an internal core. Here, we analyzed the three-dimensional structure of the organelle in detail by electron cryotomography. On the surface, knoblike particles formed a two-dimensional array, albeit with limited regularity. Analyses using a nonbinding mutant and an antibody showed that the knoblike particles correspond to a naplike structure that has been observed by negative-staining electron microscopy and is likely to be formed as a complex of P1 adhesin, the key protein for binding and gliding. The paired thin and thick plates feature a rigid hexagonal lattice and striations with highly variable repeat distances, respectively. The combination of variable and invariant structures in the internal core and the P1 adhesin array on the surface suggest a model in which axial extension and compression of the thick plate along a rigid thin plate is coupled with attachment to and detachment from the substrate during gliding. Human mycoplasma pneumonia, epidemic all over the world in recent years, is caused by a pathogenic bacterium, Mycoplasma pneumoniae. This tiny bacterium, about 2 µm in cell body length, glides on the surface of the human trachea to infect the host by binding to sialylated oligosaccharides, which are also the binding targets of influenza viruses. The mechanism of mycoplasmal gliding motility is not related to any other well-studied motility systems, such as bacterial flagella and cytoplasmic motor proteins. Here, we visualized the attachment organelle, a cellular architecture for gliding, three dimensionally by using electron cryotomography and other conventional methods. A possible gliding mechanism has been suggested based on the architectural images.