Gene transfer agents (GTAs) morphologically resemble small, double-stranded DNA bacteriophages ; however, their only known role is to package and transfer random pieces of the producing call genome to recipient calls. The best understood GTA is that of Rhodobacter capsular us, termed RcGTA. We discovered that homologues of three genes involved in natural transformation in other bacteria, ComEC , ComF , and comM , are essential for RcGTA-mediated gene acquisition. This paper gives genetic and biochemical evidence that RcGTA-borne DNA entry into cells requires the ComEC and ComF putative DNA transport proteins and genetic evidence that putative cytoplasmic ComM protein of unknown function is required for recipient capability. Furthermore, the master regulator of RcGTA production in