Fibrous Long Spacing Collagen Ultrastructure Elucidated by Atomic Force Microscopy

Paige, Matthew F.; Rainey, Jan K.; Goh, M. Cynthia

doi:10.1016/s0006-3495(98)78027-0

Cited by 64 publications

(48 citation statements)

References 33 publications

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“…''Height'' and ''deflection'' images were simultaneously recorded. Deflection images do not represent the true topography of the sample; however, they consistently revealed a higher sensitivity to small surface features and yielded images with greater detail (30). Images presented in this study are deflection images, but the quantitative measurements of cell structures were taken from the height data on the same sample.…”

Section: Methodsmentioning

confidence: 90%

Nanoscale visualization and characterization of Myxococcus xanthus cells with atomic force microscopy

Pelling

Shi

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

110

109

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Multicellular microbial communities are the predominant form of existence for microorganisms in nature. As one of the most primitive social organisms, Myxococcus xanthus has been an ideal model bacterium for studying intercellular interaction and multicellular organization. Through previous genetic and EM studies, various extracellular appendages and matrix components have been found to be involved in the social behavior of M. xanthus, but none of them was directly visualized and analyzed under native conditions. Here, we used atomic force microscopy (AFM) imaging and in vivo force spectroscopy to characterize these cellular structures under native conditions. AFM imaging revealed morphological details on the extracellular ultrastructures at an unprecedented resolution, and in vivo force spectroscopy of live cells in fluid allowed us to nanomechanically characterize extracellular polymeric substances. The findings provide the basis for AFM as a useful tool for investigating microbial-surface ultrastructures and nanomechanical properties under native conditions. force spectroscopy ͉ nonomechanics ͉ bacteria ͉ swarm

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Section: Methodsmentioning

confidence: 90%

Nanoscale visualization and characterization of Myxococcus xanthus cells with atomic force microscopy

Pelling

Shi

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

110

109

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“…Height and phase images were simultaneously recorded. Height images provide quantitative information on sample surface topography whereas phase images, although they do not represent the true topography of the sample, reveal a higher sensitivity to small surface features, resulting in images with greater detail, as previously observed (19). Phase images are derived from the phase angle between the actual vibration and the applied signal used to oscillate the AFM cantilever so that the tip intermittently taps the surface and reduces the lateral force that is applied during imaging.…”

Section: Methodsmentioning

confidence: 99%

Characterization of Changes to the Cell Surface during the Life Cycle of Streptomyces coelicolor : Atomic Force Microscopy of Living Cells

et al. 2007

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Cell surface changes that accompany the complex life cycle of Streptomyces coelicolor were monitored by atomic force microscopy (AFM) of living cells. Images were obtained using tapping mode to reveal that young, branching vegetative hyphae have a relatively smooth surface and are attached to an inert silica surface by means of a secreted extracellular matrix. Older hyphae, representing a transition between substrate and aerial growth, are sparsely decorated with fibers. Previously, a well-organized stable mosaic of fibers, called the rodlet layer, coating the surface of spores has been observed using electron microscopy. AFM revealed that aerial hyphae, prior to sporulation, possess a relatively unstable dense heterogeneous fibrous layer. Material from this layer is shed as the hyphae mature, revealing a more tightly organized fibrous mosaic layer typical of spores. The aerial hyphae are also characterized by the absence of the secreted extracellular matrix. The formation of sporulation septa is accompanied by modification to the surface layer, which undergoes localized temporary disruption at the sites of cell division. The characteristics of the hyphal surfaces of mutants show how various chaplin and rodlin proteins contribute to the formation of fibrous layers of differing stabilities. Finally, older spores with a compact rodlet layer develop surface concavities that are attributed to a reduction of intracellular turgor pressure as metabolic activity slows.The model organism Streptomyces coelicolor represents a group of soil-dwelling filamentous bacteria responsible for synthesis of a wide range of bioactive secondary metabolites, in particular, antibiotics. A good understanding of streptomycete biology has been established, based on extensive studies of S. coelicolor over many years and, more recently, availability of this bacterium's complete genome sequence (1). Of particular interest is the complex streptomycete life cycle. After spore germination, vegetative growth leads to formation of a mycelium consisting of a ramifying network of syncytial hyphae that penetrate a moist substrate by extension of hyphal tips and subapical branching. Subsequent reproductive growth often coincides with the onset of antibiotic production and proceeds with the formation of filamentous aerial hyphae that eventually undergo differentiation into chains of unigenomic spores. Several genes that are critical to various stages of this morphological differentiation have been described in S. coelicolor (5, 15), including bld genes, required for the initial growth of aerial hyphae, and whi genes, needed for the subsequent development of spore chains. Growth into the air is accompanied by a change in cell surface properties: vegetative hyphae growing in moist substrates have hydrophilic cell surfaces, whereas the aerial hyphae and spores are hydrophobic.

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“…These changes were found to be concentration-dependent, with progressively accelerated fibril formation in the presence of increasing amounts of DMP1. AFM analyses have been successful in visualizing biomolecules at nanoscale and possess the advantage of maintaining biological molecules and their interactions at near physiological conditions (30,31). When analyzed by AFM, fibrils reconstituted in the presence of DMP1 appeared to be well formed with clear D periodic banding patterns (Fig.…”

Section: Dmp1 Accelerates Type I Collagen Fibrillogenesis and Increasmentioning

confidence: 99%

Dentin Matrix Protein 1 Immobilized on Type I Collagen Fibrils Facilitates Apatite Deposition in Vitro

George

2004

Journal of Biological Chemistry

212

202

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During bone and dentin mineralization, the crystal nucleation and growth processes are considered to be matrix regulated. Osteoblasts and odontoblasts synthesize a polymeric collagenous matrix, which forms a template for apatite initiation and elongation. Coordinated and controlled reaction between type I collagen and bone/dentin-specific noncollagenous proteins are necessary for well defined biogenic crystal formation. However, the process by which collagen surfaces become mineralized is not understood. Dentin matrix protein 1 (DMP1) is an acidic noncollagenous protein expressed during the initial stages of mineralized matrix formation in bone and dentin. Here we show that DMP1 bound specifically to type I collagen, with the binding region located at the N-telopeptide region of type I collagen. Peptide mapping identified two acidic clusters in DMP1 responsible for interacting with type I collagen. The collagen binding property of these domains was further confirmed by site-directed mutagenesis. Transmission electron microscopy analyses have localized DMP1 in the gap region of the collagen fibrils. Fibrillogenesis assays further demonstrated that DMP1 accelerated the assembly of the collagen fibrils in vitro and also increased the diameter of the reconstituted collagen fibrils. In vitro mineralization studies in the presence of calcium and phosphate ions demonstrated apatite deposition only at the collagenbound DMP1 sites. Thus specific binding of DMP1 and possibly other noncollagenous proteins on the collagen fibril might be a key step in collagen matrix organization and mineralization.Mineralized tissues such as bone and dentin are hierarchically organized biocomposites possessing unique mechanical properties (1). Understanding the biomineralization process is of great value for synthesis of bioengineered bone and dentinlike materials with optimum structural properties. Type I collagen accounts for 90% of the total protein in the organic matrix of bone and dentin (1). It not only provides the structural framework with viscoelastic properties but also defines compartments for ordered mineral deposition. Studies have demonstrated that the apatite crystals are first nucleated in the gap region, and the growing mineral platelets are highly organized in a staggered manner within the collagen fibrils (2, 3).It is well established that type I collagen matrix does not have the capacity to induce matrix-specific mineral formation from metastable calcium phosphate solutions that do not spontaneously precipitate. Several in vitro studies have demonstrated that ordered mineralization of apatite on collagen fibril is impossible without additives (4, 5). As a result, much attention has been drawn to the noncollagenous proteins (NCPs) 1 that are tightly bound to the collagen fibers in mineralized tissues. Bone and/or dentin-specific NCPs are mostly acidic in nature and are rich in glutamic acid, aspartic acid, and phosphoserines (6, 7). They possess high calcium binding capacity and hydroxyapatite affinity (8 -10). In vitro ...

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Fibrous Long Spacing Collagen Ultrastructure Elucidated by Atomic Force Microscopy

Cited by 64 publications

References 33 publications

Nanoscale visualization and characterization of Myxococcus xanthus cells with atomic force microscopy

Nanoscale visualization and characterization of Myxococcus xanthus cells with atomic force microscopy

Characterization of Changes to the Cell Surface during the Life Cycle of Streptomyces coelicolor : Atomic Force Microscopy of Living Cells

Dentin Matrix Protein 1 Immobilized on Type I Collagen Fibrils Facilitates Apatite Deposition in Vitro

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