Treponema denticola
Classification
Higher order taxa
Cellular organisms; Bacteria; Spirochaetes; Spirochaetes (class); Spirochaetales; Spirochaetaceae; Treponema; Treponema denticola.
Genus
Treponema denticola
Description and significance
Treponema denticola is a motile, slender, helically shaped flexible organism. It is made up of a periplasmic flagella wound around the helical protoplasmic cylinder and encased in an outer sheath. It's habitat is anaerobic and host-associated. It grows at an optimal temperature of 30-42°C, with a pH of 6.5-8.0. It is commonly found in the human oral cavity, specifically in subgingival dental plaque, and it is often associated with periodontal disease. Periodontal disease results in inflammation of the gum tissue, bone resorbtion, and subsequent tooth loss. Periodontal disease has now become a major concern in dentistry and 80% of adults in the USA are estimated to have had periodontal disease at some point in their lives. The complete genome of T. denticola strain 35405 was sequenced by using the random shotgun method described for genomes sequenced by The Institute for Genomic Research and it was designated as the type strain by Chan et al.
Genome structure
Treponema denticola ATCC 35405 has a complete genome. It is made up of dsDNA and 1 chromosome. It is circular and the length is 2,843,201 nucleotides. The GC content is 37%. It has 2838 genes. Replicon Type: chromosome.
A plasmid sequence, pTS1, has been reported in association with T.denticola.
Cell structure and metabolism
The genome of T. denticola has shown to be involved in cell to cell signaling, as well as cell protection from external stressors such as oxidation and osmosis. It's spiral shape allows for single arrangement. It is a mobile organism that moves via rapid rotations along it's vertical axis, and rotations along the helical path allow for body flexion. A distinguishable characteristic of T. denticola is the flagella found in the space between the plasma membrane and the outer membrane (periplasmic space), which wraps around the protoplasmic cylinder.
T. denticola has a variety of mechanisms to compensate for osmosis, oxidation and many other external stressors. Studies have shown T. denticola to possess enzymes such as NADH peroxidase, NADH oxidase and superoxide dismutase.
In contrast to other spirochetes, T. denticola possesses enzymes that are essential for the synthesis of glycogen. The existence of such enzymes can be advantageous during starvation situations.
T. denticola is comprised of amino acid and peptide uptake mechanisms, including eight ABC-tyep peptide uptake systems.
The two general pathways of ATP synthesis are Glycolysis through the TCA cycle, and sugar fermentation. Since glycolysis and the TCA cycle are absent in T. denticola, ATP production must be through the sugar fermentation pathway. Furthermore, the absence of cytochromes and quinones, cells that are essential in the electron-transport chain, suggests that T. denticola does not have an electron-transport chain for energy production.
Ecology
The interaction of T. denticola with other oral bacteria, in particular Porphyromonas gingivalis, in biofilm formation is thought to be an important step in the onset of periodontal disease.
T. denticola has been shown to adhere to various cell types and basement membranes via binding to fibronectin, collagen, laminin, fibrinogen, and other substrates. Additionally, because T. denticola is a late colonizer during plaque biofilm formation, adhesion to other oral bacteria is critical; binding to Fusobacterium, B. forsythus, and P. gingivalis has been demonstrated.
Pathology
Treponema denticola is a bacterial pathogen. It causes periodontal disease and gum inflammation. It's a polymicrobial infection of the gingiva that can lead to severe effects including refractory periodontitis and acute necrotizing gingivitis, resulting in bone resorption and tooth loss.
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Current Research
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References
1) http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=397461, Rekha Seshadri, Garry S. A. Myers, Hervé Tettelin, Jonathan A. Eisen, John F. Heidelberg, Robert J. Dodson, Tanja M. Davidsen, Robert T. DeBoy, Derrick E. Fouts, Dan H. Haft, Jeremy Selengut, Qinghu Ren, Lauren M. Brinkac, Ramana Madupu, Jamie Kolonay, Scott A. Durkin, Sean C. Daugherty, Jyoti Shetty, Alla Shvartsbeyn, Elizabeth Gebregeorgis, Keita Geer, Getahun Tsegaye, Joel Malek, Bola Ayodeji, Sofiya Shatsman, Michael P. McLeod, David Šmajs, Jerrilyn K. Howell, Sangita Pal, Anita Amin, Pankaj Vashisth, Thomas Z. McNeill, Qin Xiang, Erica Sodergren, Ernesto Baca, George M. Weinstock, Steven J. Norris, Claire M. Fraser, and Ian T. Paulsen. 2004. “Comparison of the genome of the oral pathogen Treponema denticola with other spirochete genomes.” “Proc Natl Acad Sci U S A”. vol. 101, no. 15
Edited by Neena Patel, student of Rachel Larsen and Kit Pogliano.
