COMEA, A BACILLUS-SUBTILIS INTEGRAL MEMBRANE-PROTEIN REQUIRED FOR GENETIC-TRANSFORMATION, IS NEEDED FOR BOTH DNA-BINDING AND TRANSPORT

The competence-related phenotypes of mutations in each of the four ope n reading frames associated with the comE locus of Bacillus subtilis a re described. comEA and comEC are required for transformability, where as the products of comEB and of the overlapping comER, which is transc ribed in the reverse direction, are dispensable. Loss of the comEA pro duct decreases the binding of DNA to the competent cell surface and th e internalization of DNA, in addition to exhibiting a profound effect on transformability. The comEC product is required for internalization but is dispensable for DNA binding, ComEA is shown to be an integral membrane protein, as predicted from hydropathy analysis, with its C-te rminal domain outside the cytoplasmic membrane, This C-terminal domain possesses a sequence with similarity to those of several proteins kno wn to be involved in nucleic acid transactions including UvrC and a hu man protein that binds to the replication origin of the Epstein-Barr v irus.