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The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

ABSTRACT: Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called "red complex," which is associated with severe and chronic periodontitis. The surface layer (S-layer) of T. forsythia is composed of cell surface glycoproteins, such as TfsA and TfsB, and is known to play a role in adhesion/invasion and suppression of proinflammatory cytokine expression. Here we investigated the association of this S-layer with serum resistance and coaggregation with other oral bacteria. The growth of the S-layer-deficient mutant in a bacterial medium containing more than 20% non-heat-inactivated calf serum (CS) or more than 40% non-heat-inactivated human serum was significantly suppressed relative to that of the wild type (WT). Next, we used confocal microscopy to perform quantitative analysis on the effect of serum. The survival ratio of the mutant exposed to 100% non-heat-inactivated CS (76% survival) was significantly lower than that of the WT (97% survival). Furthermore, significant C3b deposition was observed in the mutant but not in the WT. In a coaggregation assay, the mutant showed reduced coaggregation with Streptococcus sanguinis, Streptococcus salivarius, and Porphyromonas gingivalis but strong coaggregation with Fusobacterium nucleatum. These results indicated that the S-layer of T. forsythia plays multiple roles in virulence and may be associated with periodontitis.

SUBMITTER: Shimotahira N

PROVIDER: S-EPMC3639587 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

Shimotahira Naohiro N Oogai Yuichi Y Kawada-Matsuo Miki M Yamada Sakuo S Fukutsuji Kenji K Nagano Keiji K Yoshimura Fuminobu F Noguchi Kazuyuki K Komatsuzawa Hitoshi H

Infection and immunity 20130128 4

Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called "red complex," which is associated with severe and chronic periodontitis. The surface layer (S-layer) of T. forsythia is composed of cell surface glycoproteins, such as TfsA and TfsB, and is known to play a role in adhesion/invasion and suppression of proinflammatory cytokine expression. Here we investigated the association of this S-layer with serum resistance and coaggregation with other oral bacteria. The ...[more]

PMID: 23357386

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Project description:Cell surface glycosylation is an important element in defining the life of pathogenic bacteria. Tannerella forsythia is a Gram-negative, anaerobic periodontal pathogen inhabiting the subgingival plaque biofilms. It is completely covered by a two-dimensional crystalline surface layer (S-layer) composed of two glycoproteins. Although the S-layer has previously been shown to delay the bacterium's recognition by the innate immune system, we characterize here the S-layer protein O-glycosylation as a potential virulence factor. The T. forsythia S-layer glycan was elucidated by a combination of electrospray ionization-tandem mass spectrometry and nuclear magnetic resonance spectroscopy as an oligosaccharide with the structure 4-Me-β-ManpNAcCONH(2)-(1→3)-[Pse5Am7Gc-(2→4)-]-β-ManpNAcA-(1→4)-[4-Me-α-Galp-(1→2)-]-α-Fucp-(1→4)-[-α-Xylp-(1→3)-]-β-GlcpA-(1→3)-[-β-Digp-(1→2)-]-α-Galp, which is O-glycosidically linked to distinct serine and threonine residues within the three-amino acid motif (D)(S/T)(A/I/L/M/T/V) on either S-layer protein. This S-layer glycan obviously impacts the life style of T. forsythia because increased biofilm formation of an UDP-N-acetylmannosaminuronic acid dehydrogenase mutant can be correlated with the presence of truncated S-layer glycans. We found that several other proteins of T. forsythia are modified with that specific oligosaccharide. Proteomics identified two of them as being among previously classified antigenic outer membrane proteins that are up-regulated under biofilm conditions, in addition to two predicted antigenic lipoproteins. Theoretical analysis of the S-layer O-glycosylation of T. forsythia indicates the involvement of a 6.8-kb gene locus that is conserved among different bacteria from the Bacteroidetes phylum. Together, these findings reveal the presence of a protein O-glycosylation system in T. forsythia that is essential for creating a rich glycoproteome pinpointing a possible relevance for the virulence of this bacterium.

Project description:Tannerella forsythia and Fusobacterium nucleatum are dental plaque bacteria implicated in the development of periodontitis. These two species have been shown to form synergistic biofilms and have been found to be closely associated in dental plaque biofilms. A number of genetic loci for TonB-dependent membrane receptors (TDR) for glycan acquisition, with many existing in association with genes coding for enzymes involved in the breakdown of complex glycans, have been identified in T. forsythia In this study, we focused on a locus, BFO_0186-BFO_0188, that codes for a predicted TDR-SusD transporter along with a putative ?-glucan hydrolyzing enzyme (BFO_0186). This operon is located immediately downstream of a 2-gene operon that codes for a putative stress-responsive extracytoplasmic function (ECF) sigma factor and an anti-sigma factor. Here, we show that BFO_0186 expresses a ?-glucanase that cleaves glucans with ?-1,6 and ?-1,3 linkages. Furthermore, the BFO_0186-BFO_0188 locus is upregulated, with an induction of ?-glucanase activity, in cobiofilms of T. forsythia and F. nucleatum The ?-glucanase activity in mixed biofilms in turn leads to an enhanced hydrolysis of ?-glucans and release of glucose monomers and oligomers as nutrients for F. nucleatum In summary, our study highlights the role of T. forsythia ?-glucanase expressed by the asaccharolytic oral bacterium T. forsythia in the development of T. forsythia-F. nucleatum mixed species biofilms, and suggest that dietary ?-glucans might contribute in plaque development and periodontal disease pathogenesis.IMPORTANCE The development of dental plaque biofilm is a complex process in which metabolic, chemical and physical interactions between bacteria take a central role. Previous studies have shown that the dental pathogens T. forsythia and F. nucleatum form synergistic biofilms and are closely associated in human dental plaque. In this study, we show that ?-glucanase from the periodontal pathogen T. forsythia plays a role in the formation of T. forsythia-F. nucleatum cobiofilms by hydrolyzing ?-glucans to glucose as a nutrient. We also unveiled that the expression of T. forsythia ?-glucanase is induced in response to F. nucleatum sensing. This study highlights the involvement of ?-glucanase activity in the development of T. forsythia-F. nucleatum biofilms and suggests that intake of dietary ?-glucans might be a contributing risk factor in plaque development and periodontal disease pathogenesis.

Dataset Information

The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

Publications

The surface layer of Tannerella forsythia contributes to serum resistance and oral bacterial coaggregation.

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