Structure and function of Hib pili from Haemophilus influenzae type b
Structure and function of Hib pili from Haemophilus influenzae type b
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DOI：
10.1128/jb.184.17.4868-4874.2002
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发表时间：
2002-09-01
影响因子：
3.2
通讯作者：
Bullitt, E
中科院分区：
文献类型：
--
作者：
Mu, XQ;Egelman, EH;Bullitt, E
致病细菌特别适合与其惯常宿主结合。随后的定殖和/或对当地环境生态位的入侵会引起疾病。 b 型流感嗜血杆菌与人鼻咽部的初始结合是由 Hib 菌毛（细菌表面表达的细丝）促进的。通过电子显微图像的三维重建，我们发现 Hib 菌毛由直径 70 埃的螺旋组成，具有三重对称性。 Hib 菌毛丝每圈有 3.0 个亚基，每组三个亚基沿螺旋轴平移 26.9 埃并绕螺旋轴旋转 53 度。对来自尿路病原性大肠杆菌表达的 Hib 菌毛和 P-菌毛的菌毛蛋白进行氨基酸序列分析，用于预测 Hib 菌毛结构中 HifA 菌毛蛋白的高度可变和免疫原性区域的物理位置。 Hib 菌毛和 P-菌毛之间的结构差异表明细菌与其宿主细胞保持结合的策略存在差异：P-菌毛被证明能够解旋至其原始长度的五倍（E. Bullitt 和 L. Makowski，Nature 373：164-167，1995），而 Hib 菌毛的损伤是通过相对于沿螺旋轴更远的亚基的轻微剪切而发生的。这种抵抗解开的能力对于 b 型流感嗜血杆菌持续粘附在鼻咽部可能很重要，鼻咽部的三股 Hib 菌毛细丝提供了坚固的系绳来抵御咳嗽和打喷嚏。
Pathogenic bacteria are specifically adapted to bind to their customary host. Disease is then caused by subsequent colonization and/or invasion of the local environmental niche. Initial binding of Haemophilus influenzae type b to the human nasopharynx is facilitated by Hib pili, filaments expressed on the bacterial surface. With three-dimensional reconstruction of electron micrograph images, we show that Hib pili comprise a helix 70 Angstrom in diameter with threefold symmetry. The Hib pilus filament has 3.0 subunits per turn, with each set of three subunits translated 26.9 Angstrom along and rotated 53 degrees about the helical axis. Amino acid sequence analysis of pilins from Hib pili and from P-pili expressed on uropathogenic Escherichia coli were used to predict the physical location of the highly variable and immunogenic region of the HifA pilin in the Hib pilus structure. Structural differences between Hib pili and P-pili suggest a difference in the strategies by which bacteria remain bound to their host cells: P-pili were shown to be capable of unwinding to five times their original length (E. Bullitt and L. Makowski, Nature 373:164-167, 1995), while damage to Hib pili occurs by slight shearing of subunits with respect to those further along the helical axis. This capacity to resist unwinding may be important for continued adherence of H. influenzae type b to the nasopharynx, where the three-stranded Hib pilus filaments provide a robust tether to withstand coughs and sneezes.