Crystalline order to high resolution in the sheath of Methanospirillum hungatei: A cross-beta structure

Stewart, Murray; Tj, Beveridge; Gd, Sprott

doi:10.1016/0022-2836(85)90019-1

Cited by 68 publications

(55 citation statements)

References 15 publications

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“…Negative staining of pure sheath (Fig. 2) combined with optical and electron diffraction has identified its p2 unit cell (a = 2.8 nm, b = 5.6, -y = 860) and suggest that the proteinaceous subunits have high cross a-structure (38). Pt shadowing and TEM have been used to demonstrate the wavelike character of the hoops which stack together to form the sheath (3), but the 2.8-nm paracrystalline repeat on the outer surface of the sheath (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Transmission electron microscopy, scanning tunneling microscopy, and atomic force microscopy of the cell envelope layers of the archaeobacterium Methanospirillum hungatei GP1

et al. 1993

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Methanospirllum hungatei GP1 possesses paracrystalline cell envelope components including end plugs and a sheath formed from stacked hoops. Both negative-stain transmission electron microscopy (TEM) and scanning tunneling microscopy (STM) distinguished the 2.8-nm repeat on the outer surface of the sheath, while negative-stain TEM alone demonstrated this repeat around the outer circumference of individual hoops. Thin sections revealed a wave-like outer sheath surface, while STM showed the presence of deep grooves that precisely defined the hoop-to-hoop boundaries at the waveform nodes. Atomic force microscopy of sheath tubes containing entrapped end plugs emphasized the end plug structure, suggesting that the sheath was malleable enough to collapse over the end plugs and deform to mimic the shape of the underlying structure. High-resolution atomic force microscopy has revised the former idea of end plug structure so that we believe each plug consists of at least four discs, each of which is -3.5 nm thick. Pt shadow TEM and STM both demonstrated the 14-nm hexagonal, particulate surface of an end plug, and STM showed the constituent particles to be lobed structures with numerous smaller projections, presumably corresponding to the molecular folding of the particle.All current techniques for ultrahigh resolution of biomolecular structure have inherent drawbacks. For example, not only does transmission electron microscopy (TEM) usually require heavy metal contrasting agents, it also produces high energy loads and high vacuums on the specimen. Only in exceptional cases, such as the purple membrane of Halobacterium spp. (18), have molecular folding data been obtained. The inception of scanning tunneling microscopy (STM) (7) and atomic force microscopy (AFM) (6) has certainly made the atomic resolution of hard, inanimate surfaces feasible, and there is a good possibility that this same resolution can be approached in biology. STM and AFM are currently being used on a number of biostructures and their constituent biopolymers, but they are still relatively new techniques in structural biology, and submolecular resolution must be interpreted with caution since biomaterials are loosely bonded and easily deformable. Specimens must be chosen with care, and close attention must be paid to the possibility of induced artifacts. It is best to take a multitechnique approach which combines high-resolution methodologies based on different principles; uniformity of high-resolution detail from each ensures accuracy of interpretation. Using this rationale, we have combined TEM, STM, and AFM to study paracrystalline surfaces possessed by the archaeobacterium Methanospirillum hungatei.STM and AFM rely on the raster scanning of a fine-tip probe over a surface, with piezoelectric ceramics to control movement to within subnanometer distances, which forms a topographical three-dimensional image of the specimen. In STM, the vertical tip displacement during scanning is depen-* Corresponding author. dent on the tunneling current between the pen...

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Section: Resultsmentioning

confidence: 99%

“…It is a hollow cylinder about 8 pum long possessing 2.8-nm particles arranged in p2 symmetry on its outer surface (a = 2.8 nm, b = 5.6 nm, and y = 860) (38). Intact sheath is a specimen for STM or AFM with a characteristic rectangular shape and a striated surface (mul-tiples of 2.8 nm) that is easily distinguished from the substrate surface (3,9,10).…”

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Transmission electron microscopy, scanning tunneling microscopy, and atomic force microscopy of the cell envelope layers of the archaeobacterium Methanospirillum hungatei GP1

et al. 1993

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“…The sheath of M. hungatei is a very resilient and nonporous structure; it is difficult to degrade (9), and it contains very small holes no more than 2.0 nm in diameter (17,20) which approximate the size of cellular substrates (H2, CO2, and NH3) and end product (CH4). The spacer and end plugs, on the other hand, consist of three plates.…”

Section: Fig 21mentioning

confidence: 99%

“…1 and 2), all confined within a paracrystalline sheath (17) as the outermost boundary layer. Proteinaceous particles, possessing cross-beta structure, occupy a 5.6-by 2.8-nm unit cell, are arranged with p2 symmetry on the surface of larger hooplike structures, and are surrounded by narrow holes which appear to penetrate the sheath (7,20). Plugs which are multilamellar partitions are found along the filament at cell spacers as well as at filament ends (4); they, like the sheath, are paracrystalline, but they possess a larger subunit spacing and p6 symmetry (17).…”

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Ultrastructure, inferred porosity, and gram-staining character of Methanospirillum hungatei filament termini describe a unique cell permeability for this archaeobacterium

1991

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By light microscopy, Methanospirillum hungatei GP1 stains gram positive at the terminal ends of each multicellular filament and gram negative at all regions in between. This phenomenon was studied further by electron microscopy and energy-dispersive X-ray spectroscopy of Gram-stained cells, using a platinum compound to replace Gram's iodine (J. A. Davies, G. K. Anderson, T. J. Beveridge, and H. C. Clark, J. Bacteriol. 156:837-845, 1983). Crystal violet-platinum precipitates could be found only in the terminal cells of each filament, which suggested that the multilamellar plugs at the filament ends were involved with stain penetration. When sheaths were isolated by sodium dodecyl sulfate-dithiothreitol treatment, the end plugs could be ejected and their layers could be separated from one another by 0.1 M NaOH treatment. Each plug consisted of at least three individual layers; two were particulate and possessed 14.0-nm particles hexagonally arranged on their surfaces with a spacing of a = b = 18.0 nm, whereas the other was a netting of 12.5-nm holes with spacings and symmetry identical to those of the particulate layers. Optical diffraction and computer image reconstruction were used to clarify the structures of each layer in an intact plug and to provide a high-resolution image of their interdigitated structures. The holes through this composite were three to six times larger than those through the sheath. Accordingly, we propose that the terminal plugs of M. hungatei allow the access of larger solutes than does the sheath and that this is the reason why the end cells of each ifiament stain gram positive whereas more internal cells are gram negative. Intuitively, since the cell spacers which partition the cells from one another along the filament contain plugs identical in structure to terminal plugs, the diffusion of large solutes for these cells would be unidirectional along the filament-cell axis.

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A Molecular Model of the Amyloid Fibril

Blake

Serpell

Sunde

et al. 2007

Novartis Foundation Symposia

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Crystalline order to high resolution in the sheath of Methanospirillum hungatei: A cross-beta structure

Cited by 68 publications

References 15 publications

Transmission electron microscopy, scanning tunneling microscopy, and atomic force microscopy of the cell envelope layers of the archaeobacterium Methanospirillum hungatei GP1

Transmission electron microscopy, scanning tunneling microscopy, and atomic force microscopy of the cell envelope layers of the archaeobacterium Methanospirillum hungatei GP1

Ultrastructure, inferred porosity, and gram-staining character of Methanospirillum hungatei filament termini describe a unique cell permeability for this archaeobacterium

A Molecular Model of the Amyloid Fibril

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