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An orthologue of Bacteroides fragilis NanH is the principal sialidase in Tannerella forsythia.

ABSTRACT: Sialidase activity is a putative virulence factor of the anaerobic periodontal pathogen Tannerella forsythia, but it is uncertain which genes encode this activity. Characterization of a putative sialidase, SiaHI, by others, indicated that this protein alone may not be responsible for all of the sialidase activity. We describe a second sialidase in T. forsythia (TF0035), an orthologue of Bacteroides fragilis NanH, and its expression in Escherichia coli. Sialidase activity of the expressed NanH was confirmed by using 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid as a substrate. Biochemical characterization of the recombinant T. forsythia NanH indicated that it was active over a broad pH range, with optimum activity at pH 5.5. This enzyme has high affinity for 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (K(m) of 32.9 +/- 10.3 microM) and rapidly releases 4-methylumbelliferone (V(max) of 170.8 +/- 11.8 nmol of 4-methylumbelliferone min(-1) mg of protein(-1)). E. coli lysates containing recombinant T. forsythia NanH cleave sialic acid from a range of substrates, with a preference for alpha2-3 glycosidic linkages. The genes adjacent to nanH encode proteins apparently involved in the metabolism of sialic acid, indicating that the NanH sialidase is likely to be involved in nutrient acquisition.

SUBMITTER: Thompson H

PROVIDER: S-EPMC2681896 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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An orthologue of Bacteroides fragilis NanH is the principal sialidase in Tannerella forsythia.

Thompson Hayley H Homer Karen A KA Rao Susmitha S Booth Veronica V Hosie Arthur H F AH

Journal of bacteriology 20090320 11

Sialidase activity is a putative virulence factor of the anaerobic periodontal pathogen Tannerella forsythia, but it is uncertain which genes encode this activity. Characterization of a putative sialidase, SiaHI, by others, indicated that this protein alone may not be responsible for all of the sialidase activity. We describe a second sialidase in T. forsythia (TF0035), an orthologue of Bacteroides fragilis NanH, and its expression in Escherichia coli. Sialidase activity of the expressed NanH wa ...[more]

PMID: 19304852

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Project description:BACKGROUND:Tannerella forsythia is a bacterial pathogen implicated in periodontal disease. Numerous virulence-associated T. forsythia genes have been described, however, it is necessary to expand the knowledge on T. forsythia's genome structure and genetic repertoire to further elucidate its role within pathogenesis. Tannerella sp. BU063, a putative periodontal health-associated sister taxon and closest known relative to T. forsythia is available for comparative analyses. In the past, strain confusion involving the T. forsythia reference type strain ATCC 43037 led to discrepancies between results obtained from in silico analyses and wet-lab experimentation. RESULTS:We generated a substantially improved genome assembly of T. forsythia ATCC 43037 covering 99% of the genome in three sequences. Using annotated genomes of ten Tannerella strains we established a soft core genome encompassing 2108 genes, based on orthologs present in >?=?80% of the strains analysed. We used a set of known and hypothetical virulence factors for comparisons in pathogenic strains and the putative periodontal health-associated isolate Tannerella sp. BU063 to identify candidate genes promoting T. forsythia's pathogenesis. Searching for pathogenicity islands we detected 38 candidate regions in the T. forsythia genome. Only four of these regions corresponded to previously described pathogenicity islands. While the general protein O-glycosylation gene cluster of T. forsythia ATCC 43037 has been described previously, genes required for the initiation of glycan synthesis are yet to be discovered. We found six putative glycosylation loci which were only partially conserved in other bacteria. Lastly, we performed a comparative analysis of translational bias in T. forsythia and Tannerella sp. BU063 and detected highly biased genes. CONCLUSIONS:We provide resources and important information on the genomes of Tannerella strains. Comparative analyses enabled us to assess the suitability of T. forsythia virulence factors as therapeutic targets and to suggest novel putative virulence factors. Further, we report on gene loci that should be addressed in the context of elucidating T. forsythia's protein O-glycosylation pathway. In summary, our work paves the way for further molecular dissection of T. forsythia biology in general and virulence of this species in particular.

Dataset Information

An orthologue of Bacteroides fragilis NanH is the principal sialidase in Tannerella forsythia.

Publications

An orthologue of Bacteroides fragilis NanH is the principal sialidase in Tannerella forsythia.

Similar Datasets

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