Competence for natural transformation in Neisseria gonorrhoeae: a model system for studies of horizontal gene transfer.

A combined effort integrating studies of gonococcal Tfp biogenesis, the data made available from the gonococcal genome sequence project and applied molecular genetics have been used to identify the fibrillar filaments themselves, the PilT protein and the ComP protein as essential components for the DNA uptake phase of competence for natural transformation. Our ongoing studies are focused on identifying and understanding the complex interactions which exist between these essential constituents. These studies may be relevant not only to the early steps of genetic transformation but also to the two other venues for horizontal gene transfer based on recent findings. First, the thin pili of IncI1 conjugal plasmids required for liquid mating belong to the type IV family of pili (Yoshida et al., 1998). Secondly, type IV pili are required for lysogenic conversion of Vibrio cholerae by a filamentous phage encoding cholera toxin (Waldor and Mekalanos, 1996). How these highly conserved surface organelles contribute to such diverse forms of DNA translocation across membranes remains to be seen.