GENETIC ORGANIZATION OF TREPONEMA DENTICOLA

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DESCRIPTION (Adapted from the Investigator's Abstract): This project will determine the DNA sequence of the chromosome of Treponema denticola, an important oral pathogen of man, associated with periodontitis. Periodontal infection affects a large segment of the population resulting in significant health costs. In addition, this bacterium is one of the few spirochetes that can be cultured outside of animals, providing an attractive system in which to study these organisms. Recently targeted mutagenesis and gene transfer have been applied to T. denticola, making it an organism of choice. This approach should allow the role and mechanisms of periodontal infection by T. denticola to be defined in detail. A genomic DNA sequence and mapped clones would provide a tremendous resource for this study. The T. denticola genome is a 3 Mb circular chromosome. Determining its DNA sequence is the next logical step in this analysis. With the recent developments in DNA sequencing technology, and the application of these advances to determination of the sequence of other bacterial genomes, a T. denticola genome project is now feasible. The complete DNA sequence of the genome will be accomplished by sequencing the ends of inserts in 24,000 plasmid clones. In addition, the ends of 600 large insert lambda and BAC clones will be sequenced to provide additional resources for closure. This will not only produce the genomic sequence, but also will provide a mapped set of clones spanning the genome. Similarities between T. denticola sequences and known genes in sequence databases will be identified by computer searches (e.g., using the BLAST program). This approach gives immediate answers to a number of important questions such as the metabolic capabilities of T. denticola, since sequence similarities are well conserved among these proteins. In addition, functions that have sequence similarity to known virulence factors will be identified. These can be readily targeted for further study since the relevant clones will be available. A genome database will also be developed for this project, which will be available on the Internet allowing researchers to assess the large amount of information on sequences, functions, clones, and other physical map features that will be generated.