title: Characterization of CagI in the cag pathogenicity island of Helicobacter pylori.
abstract: Helicobacter pylori is a highly successful human-specific gastric pathogen that infects up to 50% of the world's population. Virulent H. pylori isolates harbor the cytotoxin-associated genes pathogenicity island (cag-PAI), which encodes a type IV secretion system that translocates bacterial effector (e.g., CagA oncoprotein) molecules into host cells. Although some cag-PAI genes are shown to be required for CagA delivery or localization, the majority have no known function. In the current study, the authors performed a cell components fractionation assay and showed that CagI, one of the cag-PAI proteins located in the bacterial membrane, was not translocated into host cells. The homologous recombination method then was used to construct the isogenic mutant of H. pylori cagI, and the translocation assay was performed. The results showed that the isogenic mutant of H. pylori NCTC 11637 cagI could cause a reduction in the degree of CagA translocation. Overall, the results suggested that CagI might be an accessory component of the CagA secretion system not translocated into host cells and that it is located in the bacterial membrane.
authors: School of Medical Science and Laboratory Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013 Jiangsu, People's Republic of China.
authors: Hua
authors: H
authors: Wang
authors: Jun
authors: J
authors: Han
authors: Deyu
authors: D
authors: Chen
authors: Xiujie
authors: X
authors: Duan
authors: Xiaohuan
authors: X
authors: Gao
authors: Xiaochun
authors: X
authors: Wang
authors: Shihe
authors: S
authors: Shao
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D044404:Genomic Islands; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D021381:Protein Transport
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori