FIG. 2.

Reconstitution of dominant-negative phenotype by mixing Δ6-27p33 and p55 VacA proteins. (A) Diagram of two putative Δ6-27p88 VacA domains (Δ6-27p33 and p55) and the VacA Δ6-27 mutant protein (Δ6-27p88). The VacA amino acid numbers are indicated, and the numbering system is described in Materials and Methods. (B) E. coli extracts containing the indicated recombinant VacA proteins were mixed with acid-activated wild-type VacA purified from an H. pylori culture supernatant (H.p. VacA). Samples were then incubated with HeLa cells, and vacuolating activity was measured by a neutral red uptake assay. Results represent the means ± standard deviations from triplicate samples. *, P < 0.05 for comparison with cells treated with H. pylori VacA plus control extract (pET).