Cellular Architecture of Treponema pallidum: Novel Flagellum, Periplasmic Cone, and Cell Envelope as Revealed by Cryo Electron Tomography

JOURNAL OF MOLECULAR BIOLOGY

卷:403

Article

Liu, Jun¹  Howell, Jerrilyn K.¹  Bradley, Sherille D.¹  Zheng, Yesha¹  Zhou, Z. Hong²  Norris, Steven J.^1,3 

[1] Univ Texas Med Sch Houston, Dept Pathol & Lab Med, Houston, TX 77030 USA

[2] Univ Calif Los Angeles, Dept Microbiol Immunol & Mol Genet, Los Angeles, CA USA

[3] Univ Texas Med Sch Houston, Dept Microbiol & Mol Genet, Houston, TX 77030 USA

关键词: cryo electron tomography;    cell envelope architecture;    syphilis spirochete;    periplasmic flagellum;    bacterial structure;   

DOI  :  10.1016/j.jmb.2010.09.020

来源: Elsevier

【 摘 要 】

High-resolution cryo electron tomography (cryo-ET) was utilized to visualize Treponema pallidum, the causative agent of syphilis, at the molecular level. Three-dimensional (3D) reconstructions from 304 infectious organisms revealed unprecedented cellular structures of this unusual member of the spirochetal family. High-resolution cryo-ET reconstructions provided detailed structures of the cell envelope, which is significantly different from that of Gram-negative bacteria. The 4-nm lipid bilayer of both outer membrane and cytoplasmic membrane resolved in 3D reconstructions, providing an important marker for interpreting membrane-associated structures. Abundant lipoproteins cover the outer leaflet of the cytoplasmic membrane, in contrast to the rare outer membrane proteins visible by scanning probe microscopy. High-resolution cryo-ET images also provided the first observation of T. pallidum chemoreceptor arrays, as well as structural details of the periplasmically located cone-shaped structure at both ends of the bacterium. Furthermore, 3D subvolume averages of periplasmic flagellar motors and flagellar filaments from living organisms revealed the novel flagellar architectures that may facilitate their rotation within the confining periplasmic space. Our findings provide the most detailed structural understanding of periplasmic flagella and the surrounding cell envelope, which enable this enigmatic bacterium to efficiently penetrate tissue and to escape host immune responses. (C) 2010 Elsevier Ltd. All rights reserved.

【 授权许可】

Free