Cellular sites for the competence-provoking factor of streptococci.

Immune globulins against competent cells of group H streptococci, strains Challis and Wicky, inhibited genetic transformation to streptomycin resistance when added to competent cultures. Antibodies against noncompetent cells did not inhibit transformation of competent cells. Strain Challis is spontaneously highly transformable. Strain Wicky is very poorly transformable but can be converted to high transformability with the exocellular competence-provoking factor (CPF) produced by strain Challis. Globulins against noncompetent cells of strain Challis and Wicky also inhibited transformation when added to noncompetent cultures prior to conversion to competence. Antibodies against cells of the related strain Blackburn, however, did not inhibit transformation under any circumstances. It is concluded that, although globulins prepared against competent cells block the deoxyribonucleic acid receptor sites present in these cells, the globulins prepared against noncompetent cells prevent conversion to competence by blocking the access of CPF to specific cellular sites for this factor. Strain Blackburn seems not to contain CPF-receptive sites and is, therefore, nontransformable.