To understand how these elements can function in such a wide variety of hosts, we are analyzing the recombination reactions that occur during transposition. We have purified and characterized two transposon-encoded proteins that are involved in conjugative transposition, and have established an in vitro assay for excision of a conjugative transposon from the donor chromosome. In the course of these experiments we have found that conjugative transposons use a mechanism of transposition that is different from other bacterial transposons, retrotransposons and retroviruses, and is reminiscent of certain site-specific recombination reactions observed in bacteria, yeast and other eukaryotes. We are now investigating the role of bacterial host factors in conjugative transposition, determining the biochemical requirements for integration into the donor chromosome, and studying how the process of conjugative transposition is regulated. A second major field of study related to antibiotic resistance concerns the mechanism of action of compounds that inhibit growth of pathogenic mycobacteria, the causative agents of tuberculosis.
Tuberculosis remains the leading cause of death worldwide due to a single infectious agent.
We are trying to determine the target of a new class of antimycobacterial compounds, and to learn how mycobacteria become resistant to these compounds with the aim of developing new therapeutic agents effective in preventing tuberculosis. Specific DNA cleavage mediated by the integrase of conjugative transposon Tn916. Rudy, C.K., K. Taylor, D. Hinerfeld, J.R. Scott and G. Churchward. Excision of a conjugative transposon by the Int and Xis proteins of Tn916. Kenney, T. and G. Churchward.