Nutrient and environmental growth factors for nine oral small-sized spirochete strains containing one endoflagellum from each cell end

Identification of a Treponema denticola OppA homologue that binds host proteins present in the subgingival environment

Proteins secreted or exported by Treponema denticola have been implicated as mediators of specific interactions between the spirochete and subgingival tissues in periodontal diseases. However, limited information is available on the ability of this peptidolytic organism to bind or transport soluble peptides present in the subgingival environment. A prominent 70-kDa protein was isolated from surface extracts of T. denticola ATCC 35405. A clone expressing a portion of the protein was identified in an Escherichia coli expression library of T. denticola DNA. DNA sequence analysis showed that the cloned gene encoded a peptide homologous to OppA, the solute binding protein of an ATP-binding cassette-type peptide transporter involved in peptide uptake and environmental signaling in a wide range of bacteria. Genes encoding OppB, -C, -D, and -F were identified directly downstream of oppA in T. denticola. OppA was present in representative strains of T. denticola and in Treponema vincentii but was not detected in Treponema pectinovorum or Treponema socranskii. Immunogold electron microscopy suggested that OppA was accessible to proteins at the surface of the spirochete. Native OppA bound soluble plasminogen and fibronectin but did not bind to immobilized substrates or epithelial cells. A T. denticola oppA mutant bound reduced amounts of soluble plasminogen, and plasminogen binding to the parent strain was inhibited by the lysine analog epsilon-aminocaproic acid. Binding of soluble host proteins by OppA may be important both for spirochete-host interactions in the subgingival environment and for uptake of peptide nutrients.

Cytopathic effects of Treponema denticola chymotrypsin-like proteinase on migrating and stratified epithelial cells

The effects of Treponema denticola and its outer membrane-bound chymotrypsin-like proteinase on periodontal ligament epithelial cell cultures at different stages of maturity were studied. In sparse cultures with migrating epithelial cells, large intracellular vacuoles were formed rapidly following exposure to live T. denticola. Treponemes showing structural damage were seen occasionally inside membrane-bound vesicles. Intensive membrane blebbing occurred in infected cells and continued for up to 48 h before the cell died. Blebbing could also be induced by a purified chymotrypsin-like proteinase of T. denticola. Cortical actin and alpha-actinin of the bacterium-treated cells showed disorganization, and pericellular fibronectin was degraded by both whole T. denticola and the isolated proteinase. Epithelial cells with well-formed lateral cell contacts appeared to be more resistant to the effects of T. denticola than migrating isolated cells. In multilayer epithelial cultures, adhesion of T. denticola and membrane blebbing were observed infrequently. There was no evidence of invasion of T. denticola into epithelial multilayers. However, immunogold electron microscopy showed rapid transport of T. denticola chymotrypsin-like proteinase into newly formed large intracellular vacuoles within the epithelial layers. These vacuoles were lined by membranes studded with ribosomes. T. denticola-treated epithelial multilayers had loose cell contacts, collapsed intercellular spaces, and increased permeability. Through its capacity to cause these unique cytopathic effects, the chymotrypsin-like proteinase of T. denticola has the potential to contribute to the initiation of periodontal disease.

Development of quasi-multicellular bodies of Treponema denticola

The formation of quasi-multicellular bodies of Treponema denticola was analysed using different electron microscopical methods. These bacteria could develop four different conformations: (i) normal helical forms; (ii) twisted spirochetes, forming plaits; (iii) twisted spirochetes,forming club-like structures; (iv) spherical bodies in different size. Treponemes within spherical bodies, plaits, and clubs proved to be enclosed in a common outer sheath in which the normal arrangement of their axial flagella was lost. The development of the quasi-multicellular bodies starting from the monoforme spirochetes was elucidated and this morphogenetic process is illustrated by a schematic drawing. Factors which might be involved in the induction of the structures are discussed and their possible pathogenetic importance is considered.

Multivariate analyses of cellular fatty acids and carbohydrates of 1:2:1 and 2:4:2 spirochetes

Delimitation of small-sized spirochetes of the oral cavity can be difficult. The endoflagella pattern has long served as the main criterion for taxonomic distinction. For approved species, e.g. Treponema denticola, several endoflagella patterns are observed, which indicates that this criterion is inadequate. The present study with GC and GC-MS used fatty acids and carbohydrates of whole-cell methanolysates to distinguish 1:2:1 and 2:4:2 subgingival spirochetes. Thirteen fatty acids: C12:0, C13:0, C14:0, Ciso-14:0, C2-OH-14:0, C15:0, Cante-15:0, C16:0, Ciso-16:0, C16:1, C18:0, C18:1, and C18:2, and three carbohydrates: rhamnose, glucose, and glucosamine, were detected. The carbohydrate contents did not differ between the two groups. While 1:2:1 spirochetes contained Ciso-14:0 and Cante-15:0 acid, 2:4:2 spirochetes did not. Also multivariate analyses of quantitative fatty acid data distinguished between these groups.

Surface hydrophobicity of small oral spirochetes

The purpose of the present study was to determine the surface hydrophobicity of small oral spirochetes and to receive an impression of the molecular organization of the cell surfaces. Nine spirochete strains with one endoflagellum from each cell-end (1:2:1 spirochetes) and eight with two endoflagella from each cell-end (2:4:2 spirochetes) from subgingival plaque were examined. Two hydrophobicity assay systems were used: 1) two-phase partitioning and 2) salting-out aggregation by ammonium sulfate. The influence of heat, enzymes, saliva, and serum were examined. The 2:4:2 spirochetes were significantly more hydrophobic than the 1:2:1 spirochetes. For all strains heat treatment increased surface hydrophobicity, whereas incubation with proteases decreased surface hydrophobicity for the 1:2:1 spirochetes. The 2:4:2 spirochetes were unaffected by the proteases. Lipase and hyaluronidase affected the two morphotypes in opposite directions. Saliva did not affect the surface hydrophobicity of any of the strains, whereas rabbit serum decreased this property for the 2:4:2 strains.