Full-length sequence analysis of the vacA gene from cytotoxic and noncytotoxic Helicobacter pylori.
Some clinical isolates of Helicobacter pylori fail to express vacuolating cytotoxin, despite possessing a copy of the vacA gene on the chromosome. To gain insight into the differences between vacA from cytotoxic and noncytotoxic strains, the vacA open-reading frames from 16 cytotoxic and 22 noncytotoxic strains were sequenced. Mutations that cause truncation of VacA in 11 of 22 noncytotoxic strains were identified, including internal duplication, large deletion, 1-bp insertion, and non-sense mutations. In contrast, none of the 16 cytotoxic strains had any truncation of VacA. Four cytotoxic strains had inserted sequences downstream of vacA. Three were mini-IS605, and the other was a putative rfaJ gene that encodes lipopolysaccharide glucosyltransferase. The rfaJ gene identified in this study had a poly(C) tract, resulting in premature termination of the gene product. The phylogenetic tree based on the vacA open-reading frame indicated that two different H. pylori lineages are circulating in Japan and the West.
Second Department of Internal Medicine, Fukui Medical University, Japan.
Y
Y
Ito
T
T
Azuma
S
S
Ito
H
H
Suto
H
H
Miyaji
Y
Y
Yamazaki
Y
Y
Kohli
M
M
Kuriyama
D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D003603:Cytotoxins / Q000235:genetics*; D016368:Frameshift Mutation; D014644:Genetic Variation; D005838:Genotype; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D016366:Open Reading Frames; D010802:Phylogeny
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; C074689:VacA protein, Helicobacter pylori