scholarly journals Cryo-Electron Tomography Elucidates the Molecular Architecture of Treponema pallidum, the Syphilis Spirochete

2009 ◽  
Vol 191 (24) ◽  
pp. 7566-7580 ◽  
Author(s):  
Jacques Izard ◽  
Christian Renken ◽  
Chyong-Ere Hsieh ◽  
Daniel C. Desrosiers ◽  
Star Dunham-Ems ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Cell Envelope ◽  
Treponema Pallidum ◽  
Basal Bodies ◽  
Image Modeling ◽  
Molecular Architecture ◽  
Periplasmic Space ◽  
Membrane Biology ◽  
Cytoplasmic Filaments ◽  
Cryo Electron Tomography

ABSTRACT Cryo-electron tomography (CET) was used to examine the native cellular organization of Treponema pallidum, the syphilis spirochete. T. pallidum cells appeared to form flat waves, did not contain an outer coat and, except for bulges over the basal bodies and widening in the vicinity of flagellar filaments, displayed a uniform periplasmic space. Although the outer membrane (OM) generally was smooth in contour, OM extrusions and blebs frequently were observed, highlighting the structure's fluidity and lack of attachment to underlying periplasmic constituents. Cytoplasmic filaments converged from their attachment points opposite the basal bodies to form arrays that ran roughly parallel to the flagellar filaments along the inner surface of the cytoplasmic membrane (CM). Motile treponemes stably attached to rabbit epithelial cells predominantly via their tips. CET revealed that T. pallidum cell ends have a complex morphology and assume at least four distinct morphotypes. Images of dividing treponemes and organisms shedding cell envelope-derived blebs provided evidence for the spirochete's complex membrane biology. In the regions without flagellar filaments, peptidoglycan (PG) was visualized as a thin layer that divided the periplasmic space into zones of higher and lower electron densities adjacent to the CM and OM, respectively. Flagellar filaments were observed overlying the PG layer, while image modeling placed the PG-basal body contact site in the vicinity of the stator-P-collar junction. Bioinformatics and homology modeling indicated that the MotB proteins of T. pallidum, Treponema denticola, and Borrelia burgdorferi have membrane topologies and PG binding sites highly similar to those of their well-characterized Escherichia coli and Helicobacter pylori orthologs. Collectively, our results help to clarify fundamental differences in cell envelope ultrastructure between spirochetes and gram-negative bacteria. They also confirm that PG stabilizes the flagellar motor and enable us to propose that in most spirochetes motility results from rotation of the flagellar filaments against the PG.

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

2010 ◽  
Vol 403 (4) ◽  
pp. 546-561 ◽  
Author(s):  
Jun Liu ◽  
Jerrilyn K. Howell ◽  
Sherille D. Bradley ◽  
Yesha Zheng ◽  
Z. Hong Zhou ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Cell Envelope ◽  
Treponema Pallidum ◽  
Cellular Architecture ◽  
Cryo Electron Tomography

scholarly journals Three-Dimensional Imaging of the Highly Bent Architecture of Bdellovibrio bacteriovorus by Using Cryo-Electron Tomography

2008 ◽  
Vol 190 (7) ◽  
pp. 2588-2596 ◽  
Author(s):  
Mario J. Borgnia ◽  
Sriram Subramaniam ◽  
Jacqueline L. S. Milne
Keyword(s):  
Electron Tomography ◽  
Cell Envelope ◽  
Three Dimensional ◽  
Local Deformation ◽  
Cell Integrity ◽  
Human Pathogens ◽  
Bdellovibrio Bacteriovorus ◽  
Internal Network ◽  
Cryo Electron Tomography ◽  
Shape Changes

ABSTRACT Bdellovibrio bacteriovorus cells are small deltaproteobacterial cells that feed on other gram-negative bacteria, including human pathogens. Using cryo-electron tomography, we demonstrated that B. bacteriovorus cells are capable of substantial flexibility and local deformation of the outer and inner membranes without loss of cell integrity. These shape changes can occur in less than 2 min, and analysis of the internal architecture of highly bent cells showed that the overall distribution of molecular machines and the nucleoid is similar to that in moderately bent cells. B. bacteriovorus cells appear to contain an extensive internal network of short and long filamentous structures. We propose that rearrangements of these structures, in combination with the unique properties of the cell envelope, may underlie the remarkable ability of B. bacteriovorus cells to find and enter bacterial prey.

scholarly journals Chemoreceptors in Caulobacter crescentus: Trimers of Receptor Dimers in a Partially Ordered Hexagonally Packed Array

2008 ◽  
Vol 190 (20) ◽  
pp. 6805-6810 ◽  
Author(s):  
Cezar M. Khursigara ◽  
Xiongwu Wu ◽  
Sriram Subramaniam
Keyword(s):  
Caulobacter Crescentus ◽  
Electron Tomography ◽  
Bacterial Chemotaxis ◽  
Bacterial Cells ◽  
Molecular Architecture ◽  
Cellular Motility ◽  
Partially Ordered ◽  
Order And Disorder ◽  
Cryo Electron Tomography ◽  
Receptor Dimers

ABSTRACT Chemoreceptor arrays are macromolecular complexes that form extended assemblies primarily at the poles of bacterial cells and mediate chemotaxis signal transduction, ultimately controlling cellular motility. We have used cryo-electron tomography to determine the spatial distribution and molecular architecture of signaling molecules that comprise chemoreceptor arrays in wild-type Caulobacter crescentus cells. We demonstrate that chemoreceptors are organized as trimers of receptor dimers, forming partially ordered hexagonally packed arrays of signaling complexes in the cytoplasmic membrane. This novel organization at the threshold between order and disorder suggests how chemoreceptors and associated molecules are arranged in signaling assemblies to respond dynamically in the activation and adaptation steps of bacterial chemotaxis.

scholarly journals Molecular architecture of inner dynein arms in situ in Chlamydomonas reinhardtii flagella

2008 ◽  
Vol 183 (5) ◽  
pp. 923-932 ◽  
Author(s):  
Khanh Huy Bui ◽  
Hitoshi Sakakibara ◽  
Tandis Movassagh ◽  
Kazuhiro Oiwa ◽  
Takashi Ishikawa
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Molecular Architecture ◽  
Heavy Chains ◽  
Distal Side ◽  
Cryo Electron Tomography ◽  
Dynein Arms

The inner dynein arm regulates axonemal bending motion in eukaryotes. We used cryo-electron tomography to reconstruct the three-dimensional structure of inner dynein arms from Chlamydomonas reinhardtii. All the eight different heavy chains were identified in one 96-nm periodic repeat, as expected from previous biochemical studies. Based on mutants, we identified the positions of the AAA rings and the N-terminal tails of all the eight heavy chains. The dynein f dimer is located close to the surface of the A-microtubule, whereas the other six heavy chain rings are roughly colinear at a larger distance to form three dyads. Each dyad consists of two heavy chains and has a corresponding radial spoke or a similar feature. In each of the six heavy chains (dynein a, b, c, d, e, and g), the N-terminal tail extends from the distal side of the ring. To interact with the B-microtubule through stalks, the inner-arm dyneins must have either different handedness or, more probably, the opposite orientation of the AAA rings compared with the outer-arm dyneins.

Dissecting the molecular architecture of integrin adhesion sites by cryo-electron tomography

2010 ◽  
Vol 12 (9) ◽  
pp. 909-915 ◽  
Author(s):  
Israel Patla ◽  
Tova Volberg ◽  
Nadav Elad ◽  
Vera Hirschfeld-Warneken ◽  
Carsten Grashoff ◽  
...  
Keyword(s):  
Electron Tomography ◽  
Molecular Architecture ◽  
Adhesion Sites ◽  
Cryo Electron Tomography

scholarly journals The molecular architecture of engulfment during Bacillus subtilis sporulation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Kanika Khanna ◽  
Javier Lopez-Garrido ◽  
Ziyi Zhao ◽  
Reika Watanabe ◽  
Yuan Yuan ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Mother Cell ◽  
Cell Biology ◽  
Focused Ion Beam ◽  
High Spatial Resolution ◽  
Electron Tomography ◽  
Ion Beam ◽  
Molecular Architecture ◽  
Native State ◽  
Cryo Electron Tomography

The study of bacterial cell biology is limited by difficulties in visualizing cellular structures at high spatial resolution within their native milieu. Here, we visualize Bacillus subtilis sporulation using cryo-electron tomography coupled with cryo-focused ion beam milling, allowing the reconstruction of native-state cellular sections at molecular resolution. During sporulation, an asymmetrically-positioned septum generates a larger mother cell and a smaller forespore. Subsequently, the mother cell engulfs the forespore. We show that the septal peptidoglycan is not completely degraded at the onset of engulfment. Instead, the septum is uniformly and only slightly thinned as it curves towards the mother cell. Then, the mother cell membrane migrates around the forespore in tiny finger-like projections, whose formation requires the mother cell SpoIIDMP protein complex. We propose that a limited number of SpoIIDMP complexes tether to and degrade the peptidoglycan ahead of the engulfing membrane, generating an irregular membrane front.

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