Analysis of the SHP-2 Binding Site of Helicobacter pylori CagA Protein in Korean

Recently the pathological actions of CagA of Helicobacter pylori (H. pylori) on gastric epithelial cells have been reported. CagA is directly injected into the host cytoplasm and undergoes tyrosine phosphorylation in the cells. In addition, translocated CagA forms a physical complex with SHP-2. There are two major CagA subtypes according to the amino acid sequence in the 3`region of CagA; i) the East Asian type (A-B-D of EPIYA motifs) and ii) the Western type (A-B-C of EPIYA motifs). Repeated EPIYA motifs in the 3`region of CagA are involved in the interaction with SHP-2. The East Asian type conferred stronger SHP-2 binding activity than the Westrrn type of CagA. Here we analyzed the amino acid sequences of the SHP-2 binding site of cagA gene in H. pyzori, and investigated whether there is my relationship between the diversities of cagA and the disease out-come in Korea. Most of Korean H. pylori strains showed A-B-D motifs(the East Asian type), and only one strain showed A-B-B-D motifs. In Korea, the incidence of atrophic gastritis and gastric cancer is significantly high compared with Western countries. The high frequency of the East Asian type CagA among Korean H. pylori strains would be involved in increasing the risk of gastric cancer in Korean populations.