Arrangement of gene loci involved in H. pylori transformation competence. Gene arrangement of the four loci that to date have been shown to be necessary for H. pylori transformation competence. Gene orientations, numbers, and designations are shown according to the genome sequence of H. pylori strain J99. Localizations and putative functions of the encoded proteins are indicated. Abbreviations: IM, inner membrane; PP, periplasmic space; CY, cytoplasm. The proteins marked by an asterisk are associated with membrane fractions as well. For the DprA and ComH proteins, no experimental data are available.