MEMBRANE TARGETING OF RECA DURING GENETIC-TRANSFORMATION

Recombination in prokaryotes and eukaryotes is mediated by the RecA fa mily of proteins. Although the interactions between RecA and DNA are w ell studied, the cellular location of these interactions is not known. Using genetic transformation of Streptococcus pneumoniae as a model s ystem, there was increased expression of a protein, colligrin, and Rec A, products of the rec locus during genetic transfer. These proteins f ormed a complex and were found associated with the membranes of geneti cally competent cells. With immunoelectron microscopy and subcellular fractionation, we showed that the induction of competence led to the t ranslocation of RecA and colligrin to the membrane and to the formatio n of clusters of RecA in a colligrin-dependent step. Based on the beha viour of colligrin and RecA during genetic exchange and the numerous p roteins in prokaryotes and eukaryotes with domains similar to colligri n, we suggest that there may exist a family of proteins, which gathers macromolecules at specific sites in biological membranes.