Binding of rabbit gamma globulin by competent Bacillus subtilis cultures.

Deoxyribonucleic acid (DNA)-mediated transformation of Bacillus subtilis can be inhibited by antibodies which specifically interact with single-stranded DNA. This inhibition occurs at a time when the transformation reaction is insensitive to deoxyribonuclease. Studies with radioactive proteins revealed that the maximal binding of gamma globulin occurs immediately preceding the development of maximal competence in the population. Other proteins, such as deoxyribonuclease cytochrome c and serum albumin also adsorb to the surface of the cell. After treatment with lysozyme, 67% of the radioactive gamma globulin remains associated with the cytoplasmic membrane. These findings suggest that the DNA is complexed in a deoxyribonuclease-insensitive form to the surface of the cell and is converted to a single-stranded state prior to transport past the membrane and integration into the chromosome.