This application is an extension of current research examining the association between H2S production and virulence of Treponema denticola. T. denticola has been identified as an important member of a consortium of microorganisms as etiologic in the initiation and progression of periodontal diseases. In addition, the existence of volatile sulfur compounds produced at destructive sites is a characteristic feature of periodontal diseases, with H2S as a major compound in this family. Nevertheless, the metabolic pathways used to produce H2S are not well understood. Previous studies suggest that glutathione present in host cells can be a substrate for H2S production. Recently, we have shown that T. denticola has the capacity to utilize glutathione as a substrate to produce high levels of H2S. We have identified three enzymes that are required for the successful metabolism of glutathione: gamma-glutamyltransferase (GGT), cysteinylglycinase (CGase), and cystalysin. GGT converts glutathione into Cys-Gly and glutamic acid; CGase catalyze Cys-Gly to Cys and glycine; and cystalysin digests L-cysteine into H2S, ammonia, and pyruvate. We have also demonstrated that the addition of cystalysin and L-cysteine resulted in apoptosis of HGF and PDL cells and that glutathione was essential for lesion formation by T. denticola in an animal model. Based on these and other studies, three Specific Aims are proposed using biochemical, molecular genetic, and cell biologic studies to address the hypothesis that these three metabolic enzymes play a key role in T denticola pathogenesis.
Specific Aim 1 : To molecularly characterize the genes and proteins involved in converting glutathione to H2S.
Specific Aim 2 : To genetically characterize, by gene inactivation, the enzyme pathway of T. denticola that produces H2S from glutathione.
Specific Aim 3 : To measure the effects of the H2S/NH3 producing pathway on T. denticola virulence in vitro and in vivo. This application is designed to provide both seminal and critical information about the enzyme pathway of T. denticola to produce H2S from glutathione. The outcomes will elucidate the mechanisms of action that each member of the enzyme pathway plays in the virulence capacity of T. denticola.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
2R01DE013819-04
Application #
6722461
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Program Officer
Lunsford, Dwayne
Project Start
2000-09-01
Project End
2007-12-31
Budget Start
2004-03-01
Budget End
2004-12-31
Support Year
4
Fiscal Year
2004
Total Cost
$205,865
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Dentistry
Type
Schools of Dentistry
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
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Chu, Lianrui; Lai, Yanlai; Xu, Xiaoping et al. (2008) A 52-kDa leucyl aminopeptidase from treponema denticola is a cysteinylglycinase that mediates the second step of glutathione metabolism. J Biol Chem 283:19351-8
Lai, Yanlai; Chu, Lianrui (2008) Novel mechanism for conditional aerobic growth of the anaerobic bacterium Treponema denticola. Appl Environ Microbiol 74:73-9
Chu, Lianrui; Xu, Xiaoping; Dong, Zheng et al. (2003) Role for recombinant gamma-glutamyltransferase from Treponema denticola in glutathione metabolism. Infect Immun 71:335-42
Chu, Lianrui; Dong, Zheng; Xu, Xiaoping et al. (2002) Role of glutathione metabolism of Treponema denticola in bacterial growth and virulence expression. Infect Immun 70:1113-20