PHYSICAL MAP OF THE GENOME OF TREPONEMA-PALLIDUM SUBSP PALLIDUM (NICHOLS)

A physical map of the chromosome of Treponema pallidum subsp. pallidum (Nichols), the causative agent of syphilis,,vas constructed from rest riction fragments produced by NotI, SfiI, and SrfI. These rare-cutting restriction endonucleases cleaved the T. pallidum genome into 16, 8, and 15 fragments, respectively. Summation of the physical lengths of t he fragments indicates that the chromosome of T. pallidum subsp. palli dum is approximately 1,030 to 1,080 kbp in size. The physical map was constructed by hybridizing a variety of probes to Southern blots of si ngle and double digests of T. pallidum genomic DNA separated by contou r-clamped homogeneous electric field electrophoresis. Probes included cosmid clones constructed from T. pallidum subsp. pallidum genomic DNA , restriction fragments excised from gels, and selected genes. Physica l mapping confirmed that the chromosome of T. pallidum subsp. pallidum is circular, as the SfiI and SrfI maps formed complete circles. A tot al of 13 genes, including those encoding five membrane lipoproteins (t pn47, tpn41, tpn29-35, tpn17, and tpnl5), a putative outer membrane po rin (tpn50), the flagellar sheath and hook proteins (flaA and flgE), t he cytoplasmic filament protein (cfpA), 16S rRNA (rrnA), a major sigma factor (rpoD), and a homolog of cysteinyl-tRNA synthetase (cysS), hav e been localized in the physical map as a first step toward studying t he genetic organization of this noncultivable pathogen.