Plays a role in the competence of cells to be transformed. It inhibits the activity of the DNA-entry nuclease. This protein is a subunit of a 75 kDa protein complex, which governs binding and entry of donor DNA. The complex is a tetramer of two subunits of the DNA-entry nuclease and two subunits of a competence-specific protein. Only the complex is able to bind ds- and ss-DNA.