Relationship between the competence antigen and the competence-activator substance in pneumococci.

Tomasz, Alexander (The Rockefeller Institute, New York, N.Y.), and Samuel M. Beiser. Relationship between the competence antigen and the competence-activator substance in pneumococci. J. Bacteriol. 90:1226-1232. 1965.-Antisera prepared against pneumococci in their competent phase inhibit deoxyribonuoleic acid (DNA)-mediated genetic transformation as well as binding of radioactive DNA by the cells. The same sera do not inhibit transformation of competent Haemophilus influenzae and Bacillus subtilis cells, but transformation of a Streptococcus strain genetically related to pneumococci is inhibited. The kinetics of immune inhibition of transformation resembles the inactivation of bacteriophage by phage-neutralizing antisera. The appearance of the competence antigen on the surface of pneumococci can be induced by the competence-activator substance. Antisera prepared against competent pneumococci can also inhibit the conversion of incompetent cells to competence by the competence-activator substance. The possibility is considered that part of the new antigenic determinant appearing on the cell surface during competence may be the activator itself.