PHYSICAL MAP OF THE TREPONEMA-DENTICOLA CIRCULAR CHROMOSOME

A physical map of the Treponema denticola ATCC 33520 genome was constr ucted by pulsed-field gel electrophoresis and DNA hybridization. The o rganism possesses a single, circular chromosome of approximately 3.0 M bp and a 2.6-kbp circular plasmid, pTD1. The physical map of the Af T- rich genome was constructed with the rare-cutting restriction enzymes AscI, NotI, and SrfI, which have 8-bp Gt-C-rich recognition sites. The genes flgE, tdpA, and prtB encoding the flagellar hook protein, a 53- kDa immunogenic protein, and chymotrypsinlike protease, respectively, were located on the map. This treponeme was found to have two copies o f each of the rRNA genes, as has been found to be the case for both Tr eponema phagedenis and Treponema pallidum.