FIG. 2.

Construction of precise deletions of comB2 (hp0015) or comB3 (hp0016) and genetic complementation. (A) Precise deletions of the hp0015, hp0016, or hp0015 to hp0017 genes were constructed by replacing the corresponding gene sequences with a chloramphenicol acetyltransferase (cat) or kanamycin (aphA-3) resistance gene cassette. (B) Complementation of the corresponding genes was obtained by cloning the comB4, comB3-comB4, or comB2 to comB4 gene(s) in the shuttle vector pHel2 behind the H. pylori flaA promoter (P) of plasmid pDH80 (pAK20 to pAK22) and transfer of the shuttle plasmid into P1Δhp0015-hp0017::aphA-3. The competence for genetic transformation of the corresponding strains is indicated (+ or −). For quantitative data of transformation experiments, see Table 3.