UPTAKE-SEQUENCE-INDEPENDENT DNA TRANSFORMATION EXISTS IN NEISSERIA-GONORRHOEAE

A DNA transformation dose-response curve of piliated (P+) gonococci wi th the use of cloned DNA containing a pilE2-cat fusion showed saturati on at high and low levels of transforming DNA. At low DNA concentratio ns, transformation of the P+ strain MS11-A was effectively inhibited b y a 1000-fold molar excess of the gonococcal transformation uptake seq uence (GCUS). The same molar excess of the GCUS did not inhibit transf ormation of MS11-A at high DNA concentrations. In MS11-B2, a nonpiliat ed (P-), pilin-nonproducing, isogenic variant of MS11-A, the GCUS did not inhibit transformation at any level of transforming DNA. These dat a suggest that two mechanisms of transformation exist in P+ cells: one which utilizes the GCUS and one which does not. In MS11-B2 P- cells, no evidence was found for the presence of the GCUS-dependent mechanism , suggesting that transformation in this background occurs solely by t he GCUS-independent mechanism.