Submitted to: World Congress on Anaerobic Bacteria and Infections
Publication Type: Abstract Only
Publication Acceptance Date: October 6, 1998
Publication Date: N/A
Technical Abstract: The gene transfer agent VSH-1 of S. hyodysenteriae is the first mechanism of natural genetic exchange to be identified for a spirochete. A major obstacle to investigating VSH-1 is the inability to identify its genes. To overcome this obstacle, five proteins associated with VSH-1 virion heads (13, 19, 38 kDa) or tails (53, 101 kDa) were purified and their N-terminal ends were sequenced. Based on the amino acid sequences, oligonucleotides complementary to the corresponding genes were designed and used to amplify adjacent VSH-1 genes within the S hyo chromosome by PCR techniques. In this way, portions of the gene for the 19-kDa and 13-kDa proteins were cloned and sequenced. By "chromosome walking techniques," genes for the five VSH-1 proteins were identified within a 12-kB DNA region. This result suggests an individual virion, containing 7.5 kB DNA, does not carry DNA sufficient for self-replication. By Southern blot hybridization, a 343-bp DNA probe was used to detect the 38-kDa protein gene in restriction enzyme-digested DNAs from Serpulina strains. The DNA of every strain examined, representing six Serpulina species, contained a single hybridizing fragment. Thus, VSH-1-like agents are widely distributed among Serpulina species. Gene transfer mechanisms among intestinal anaerobic bacteria are largely unknown. Our results suggest that VSH-1 is a unique and previously unrecognized mechanism of bacterial gene transfer in the intestinal ecosystem.