Native cellular architecture of Treponema denticola revealed by cryo-electron tomography

Izard, Jacques; Hsieh, Chyongere; Limberger, Ronald J.; Mannella, Carmen A.; Marko, Michael

doi:10.1016/j.jsb.2008.03.009

Cited by 38 publications

(57 citation statements)

References 52 publications

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“…4). The outer surfaces of the basal bodies (i.e., those parts of the basal bodies that directly face the periplasmic space), with the hook region exposed, were approximately 38 nm in diameter, which is similar to those reported for T. primitia (35 nm) but somewhat greater than those of T. denticola (29 nm) (21,33). Each basal body appeared as a ring, with a dense region in the center.…”

Section: Overall Cell Morphologysupporting

confidence: 73%

“…For example, electron microscopy of hydrated sections of E. coli and Pseudomonas aeruginosa indicated that the periplasmic space is markedly thinner than indicated by results previously obtained using fixed cells (28). Here we analyzed the structure of B. burgdorferi using electron cryotomography and compared our results to those recently reported for Treponema primitia and Treponema denticola (21,34). We found not only that is its periplasmic space quite thin but that the periplasmic flagella do not form a bundle as previously thought (18,31).…”

supporting

confidence: 49%

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The Flat-Ribbon Configuration of the Periplasmic Flagella of Borrelia burgdorferi and Its Relationship to Motility and Morphology

et al. 2009

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Electron cryotomography was used to analyze the structure of the Lyme disease spirochete, Borrelia burgdorferi. This methodology offers a new means for studying the native architecture of bacteria by eliminating the chemical fixing, dehydration, and staining steps of conventional electron microscopy. Using electron cryotomography, we noted that membrane blebs formed at the ends of the cells. These blebs may be precursors to vesicles that are released from cells grown in vivo and in vitro. We found that the periplasmic space of B. burgdorferi was quite narrow (16.0 nm) compared to those of Escherichia coli and Pseudomonas aeruginosa. However, in the vicinity of the periplasmic flagella, this space was considerably wider (42.3 nm). In contrast to previous results, the periplasmic flagella did not form a bundle but rather formed a tight-fitting ribbon that wraps around the protoplasmic cell cylinder in a right-handed sense. We show how the ribbon configuration of the assembled periplasmic flagella is more advantageous than a bundle for both swimming and forming the flat-wave morphology. Previous results indicate that B. burgdorferi motility is dependent on the rotation of the periplasmic flagella in generating backward-moving waves along the length of the cell. This swimming requires that the rotation of the flagella exerts force on the cell cylinder. Accordingly, a ribbon is more beneficial than a bundle, as this configuration allows each periplasmic flagellum to have direct contact with the cell cylinder in order to exert that force, and it minimizes interference between the rotating filaments.Spirochetes are a monophyltic phylum with a unique morphology (8, 35) These bacteria have a protoplasmic cell cylinder, which includes the plasma membrane and peptidoglycan layer, and an outer membrane. The region between the plasma membrane and the outer membrane constitutes the periplasmic space. The periplasmic flagella, which are subterminally attached to the ends of the protoplasmic cell cylinder, reside in this space. A given periplasmic flagellum is attached at only one end, extends toward the center of the cell, and is rotated by a basal motor anchored to the protoplasmic cell cylinder. The periplasmic flagella at each end form a group of filaments, and depending on the species, each group contains from one to hundreds of periplasmic flagella.The motility of Borrelia burgdorferi, the Lyme disease spirochete, is quite complex (see references 10, 25, and 26 for recent reviews on spirochete motility). This species is capable of swimming both in low-viscosity media and also in viscous gellike media that inhibit the motility of most other bacteria (19,23). A typical B. burgdorferi cell runs, stops, flexes (pauses and forms a distorted shape), and reverses direction. Several lines of evidence indicate that during a run, the two groups of 7 to 11 periplasmic flagella rotate asymmetrically; i.e., one group rotates clockwise (CW), and the other rotates counter-clockwise (CCW) (10,24,32). (As a frame of reference, a given fla...

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Section: Overall Cell Morphologysupporting

confidence: 73%

supporting

confidence: 49%

The Flat-Ribbon Configuration of the Periplasmic Flagella of Borrelia burgdorferi and Its Relationship to Motility and Morphology

et al. 2009

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“…However, we were surprised that 26.4% (versus only 1.7% in the wild type) ( Table 2) of the motors/periplasmic flagella were oriented toward the cell pole rather than extending toward the middle of the cell body. This remarkable phenotype has not been observed for previously characterized spirochetal flagellar mutants (24,41). FliL is therefore likely to play a role in defining the orientation of periplasmic flagella in B. burgdorferi (Fig.…”

Section: Discussionmentioning

confidence: 61%

“…Recently, cryo-electron tomography (cryo-ET) was utilized to determine the molecular architecture of the spirochete flagellar motor in situ (24,25,40,41). These studies suggested that the overall spirochetal flagellar motor structures (the MS ring, the C ring, and the export apparatus) are similar to those of other bacteria, e.g., E. coli (9,25,31,33,40,41,47).…”

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confidence: 99%

A Novel Gene Inactivation System Reveals Altered Periplasmic Flagellar Orientation in aBorrelia burgdorferi fliLMutant

et al. 2011

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Motility and chemotaxis are essential components of pathogenesis for many infectious bacteria, includingBorrelia burgdorferi, the causative agent of Lyme disease. Motility and chemotaxis genes comprise 5 to 6% of the genome of B. burgdorferi, yet the functions of most of those genes remain uncharacterized, mainly due to the paucity of a nonpolar gene inactivation system. In this communication, we describe the development of a novel gene inactivation methodology to target B. burgdorferi fliL, a putative periplasmic flagellar gene located in a large motility operon and transcribed by RNA polymerase containing 70 . Although the morphology of nonpolar fliL mutant cells was indistinguishable from that of wild-type cells, the mutant exhibited a defectivemotility phenotype. Cryo-electron tomography (cryo-ET) of intact organisms revealed that the periplasmic flagella in the fliL mutant were frequently tilted toward the cell pole instead of their normal orientation toward the cell body. These defects were corrected when the mutant was complemented in cis. Moreover, a comparative analysis of flagellar motors from the wild type and the mutant provides the first structural evidence that FliL is localized between the stator and rotor. Our results suggest that FliL is likely involved in coordinating or regulating the orientation of periplasmic flagella in B. burgdorferi.Borrelia burgdorferi is the causative agent of Lyme disease and belongs to a group of bacteria called spirochetes. B. burgdorferi cells have a characteristic flat-wave morphology and unique means of motility (9,10,19,35). As a result of its unique morphology and motility, B. burgdorferi is able to traverse viscous gel-like media in which most other flagellated bacteria slow down or stop (30). Consequently, B. burgdorferi may efficiently bore through host tissues, leading to pathogenesis in the joints, nervous system, and heart (19,30,54). The motility of B. burgdorferi results from the coordinated rotation of the periplasmic flagella residing between the outer membrane and the cell cylinder (9,10,12,20,33,35). The current swimming model suggests that a run occurs when the anterior periplasmic flagella rotate in one direction (e.g., counterclockwise [CCW]) and the posterior flagella rotate in the opposite direction (clockwise [CW]). Reversals occur when periplasmic flagella at both poles of the cell change their direction of rotation. During a nontranslational mode (flex), the periplasmic flagella at both cell poles rotate in the same direction (9,20,35).Bacterial flagella are composed of three major parts: the motor, hook, and filament. The motor can be divided into two functional units, the rotor and the stator. The stator is the torque generator consisting of the MotA-MotB complex. The rotor is composed, minimally, of the MS ring (FliF), the rod, and the switch complex (FliG, FliM, and FliN). In B. burgdorferi, the periplasm-localized flagellar filament consists of the core protein FlaB and the sheath protein FlaA (17, 46). There are 7 to 11 filaments conne...

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“…This technique involves collecting a tilt series of images from different angles at high magnification and computationally reconstructing a 3-D density map of the intact organism. Recently, cryo-ET has been extensively utilized to study many spirochetes (1,7,14,15,19,28,32,33), particularly, in our hands, to study the intact flagellar motor structure of B. burgdorferi (25) as well as the cell envelope architecture of T. pallidum (24).…”

mentioning

confidence: 99%

Three-Dimensional Structures of Pathogenic and Saprophytic Leptospira Species Revealed by Cryo-Electron Tomography

Raddi¹,

Morado²,

Yan

et al. 2012

J Bacteriol

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e Leptospira interrogans is the primary causative agent of the most widespread zoonotic disease, leptospirosis. An in-depth structural characterization of L. interrogans is needed to understand its biology and pathogenesis. In this study, cryo-electron tomography (cryo-ET) was used to compare pathogenic and saprophytic species and examine the unique morphological features of this group of bacteria. Specifically, our study revealed a structural difference between the cell envelopes of L. interrogans and Leptospira biflexa involving variations in the lipopolysaccharide (LPS) layer. Through cryo-ET and subvolume averaging, we determined the first three-dimensional (3-D) structure of the flagellar motor of leptospira, with novel features in the flagellar C ring, export apparatus, and stator. Together with direct visualization of chemoreceptor arrays, DNA packing, periplasmic filaments, spherical cytoplasmic bodies, and a unique "cap" at the cell end, this report provides structural insights into these fascinating Leptospira species.

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Native cellular architecture of Treponema denticola revealed by cryo-electron tomography

Cited by 38 publications

References 52 publications

The Flat-Ribbon Configuration of the Periplasmic Flagella of Borrelia burgdorferi and Its Relationship to Motility and Morphology

The Flat-Ribbon Configuration of the Periplasmic Flagella of Borrelia burgdorferi and Its Relationship to Motility and Morphology

A Novel Gene Inactivation System Reveals Altered Periplasmic Flagellar Orientation in aBorrelia burgdorferi fliLMutant

Three-Dimensional Structures of Pathogenic and Saprophytic Leptospira Species Revealed by Cryo-Electron Tomography

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