Periodontitis is a chronic inflammatory disease of the tooth supporting tissue that leads to tooth loss. The disease results from the inflammation triggered by a group of Gram-negative pathogens that colonize the gingival and sub-gingival locations as polymicrobial biofilms. One of the pathogens present in these biofilms and strongly implicated in periodontitis is Tannerella forsythia. Its role in pathogenesis has been confirmed by reproduction of the disease (periodontal bone destruction) in animal models following infection with the bacterium. Uniquely, T. forsythia requires exogenous MurNAc, an essential peptidoglycan aminosugar, for growth. To date, this has not been observed for other pathogens but is likely due to the absence of genes encoding the key enzyme in its genome for the de novo synthesis of MurNAc from simple sugars. Moreover, despite its clear ability to utilize exogenously supplied MurNAc, the Tannerella genome also lacks homologs of PTS-type MurNAc transporters present in other bacteria. These unique characteristics suggest that novel mechanisms for MurNAc uptake and utilization exist in the bacterium. Surprisingly, T. forsythia can grow in in vitro biofilms in the absence of MurNAc if sialic acid-containing sialoglycoproteins are supplemented instead. We predict that in vivo the MurNAc requirements of the bacterium are fulfilled by scavenging muropeptides and MurNAc released by cohabiting bacteria during their cell wall recycling and during biofilm growth by MurNAc synthesis from sialic acid, which is most likely made available in vivo by the action of bacterial sialidase(s) on host glycoproteins. Thus, the objectives of this study are to define the mechanisms by which T. forsythia transports exogenous MurNAc for peptidoglycan synthesis (Aim1), and discover the metabolic pathways by which MurNAc is synthesized from sialic acid in the bacterium (Aim 2). Overall, this study will provide a basic understanding of the unique physiology of T. forsythia in relation to MurNAc uptake/utilization as well as novel insights into the nutritional requirements of the bacterium in the human oral cavity. This knowledge will aid in designing new antimicrobial agents targeting MurNAc uptake/utilization pathways to control T. forsythia growth. Moreover, the information will be valuable for understanding other bacteria which have not yet been cultivated/identified but might have similar physiological requirements.

Public Health Relevance

Tannerella forsythia is an oral bacterium implicated in periodontitis, a chronic inflammatory disease of the tooth supporting tissue resulting in tooth loss. This project aims to identify the novel biochemical pathways by which an essential aminosugar N-acteyl muramic acid is transported and utilized in the bacterium. This knowledge will be useful in designing novel antimicrobial agents against the bacterium and thus in the treatment of periodontitis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21DE022870-02
Application #
8845539
Study Section
Oral, Dental and Craniofacial Sciences Study Section (ODCS)
Program Officer
Lunsford, Dwayne
Project Start
2014-05-05
Project End
2017-04-30
Budget Start
2015-05-01
Budget End
2017-04-30
Support Year
2
Fiscal Year
2015
Total Cost
Indirect Cost
Name
State University of New York at Buffalo
Department
Dentistry
Type
Schools of Dentistry/Oral Hygn
DUNS #
038633251
City
Amherst
State
NY
Country
United States
Zip Code
14228
Ruscitto, A; Sharma, A (2018) Peptidoglycan synthesis in Tannerella forsythia: Scavenging is the modus operandi. Mol Oral Microbiol 33:125-132
Honma, Kiyonobu; Ruscitto, Angela; Sharma, Ashu (2017) ?-glucanase activity of the oral bacterium Tannerella forsythia contributes to the growth of a partner species, Fusobacterium nucleatum, in co-biofilms. Appl Environ Microbiol :
Ruscitto, Angela; Honma, Kiyonobu; Veeramachineni, Vamsee M et al. (2017) Regulation and Molecular Basis of Environmental Muropeptide Uptake and Utilization in Fastidious Oral Anaerobe Tannerella forsythia. Front Microbiol 8:648
Ruscitto, Angela; Hottmann, Isabel; Stafford, Graham P et al. (2016) Identification of a Novel N-Acetylmuramic Acid Transporter in Tannerella forsythia. J Bacteriol 198:3119-3125
Honma, Kiyonobu; Ruscitto, Angela; Frey, Andrew M et al. (2016) Sialic acid transporter NanT participates in Tannerella forsythia biofilm formation and survival on epithelial cells. Microb Pathog 94:12-20
Stafford, Graham P; Chaudhuri, Roy R; Haraszthy, Violet et al. (2016) Draft Genome Sequences of Three Clinical Isolates of Tannerella forsythia Isolated from Subgingival Plaque from Periodontitis Patients in the United States. Genome Announc 4: