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首页> 外文期刊>Journal of bacteriology >Structure of the Haemophilus influenzae HMW1B Translocator Protein: Evidence for a Twin Pore
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Structure of the Haemophilus influenzae HMW1B Translocator Protein: Evidence for a Twin Pore

机译：流感嗜血杆菌HMW1B转运蛋白的结构：双孔的证据。

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摘要

Secretion of the Haemophilus influenzae HMW1 adhesin occurs via the two-partner secretion pathway and requires the HMW1B outer membrane translocator. HMW1B has been subjected to extensive biochemical studies to date. However, direct examination of the structure of HMW1B has been lacking, leaving fundamental questions about the oligomeric state, the membrane-embedded β-barrel domain, the approximate size of the β-barrel pore, and the mechanism of translocator activity. In the current study, examination of purified HMW1B by size exclusion chromatography and negative staining electron microscopy revealed that the predominant species was a dimer. In the presence of lipid, purified HMW1B formed two-dimensional crystalline sheets. Examination of these crystals by cryo-electron microscopy allowed determination of a projection structure of HMW1B to 10 ? resolution. The native HMW1B structure is a dimer of β-barrels, with each β-barrel measuring 40 ? by 50 ? in the two orthogonal directions and appearing largely occluded, leaving only a narrow pore. These observations suggest that HMW1B undergoes a large conformational change during translocation of the 125-kDa HMW1 adhesin.
机译：流感嗜血杆菌HMW1黏附素的分泌通过两个伙伴的分泌途径发生，需要HMW1B外膜移位器。迄今为止，HMW1B已进行了广泛的生化研究。然而，缺乏对HMW1B结构的直接检查，留下了有关寡聚状态，膜包埋的β-桶结构域，β-桶孔的近似大小以及易位子活性机制的基本问题。在当前的研究中，通过尺寸排阻色谱法和负染色电子显微镜检查纯化的HMW1B，发现主要物质是二聚体。在脂质存在下，纯化的HMW1B形成二维晶体片。通过冷冻电子显微镜检查这些晶体，可以确定HMW1B至10μm的投影结构。解析度。天然的HMW1B结构是β-桶的二聚体，每个β-桶的尺寸为40？减50？在两个正交方向上，并且大部分被遮挡，仅留下一个狭窄的孔。这些观察结果表明HMW1B在125 kDa HMW1粘附素易位过程中发生了很大的构象变化。

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