title: The Helicobacter pylori protein CagM is located in the transmembrane channel that is required for CagA translocation.
abstract: Helicobacter pylori (H. pylori) is a human gastric pathogen that colonizes the stomach in more than 50 % of the world's human population. Infection with this bacterium can induce several gastric diseases ranging from gastritis to peptic ulcer and gastric cancer. Virulent H. pylori isolates harboring the cag pathogenicity island (cag PAI), which encodes a Type IV Secretion System (T4SS), form a pilus for the injection of its major virulence protein CagA into gastric cells. Several cag PAI genes have been identified as homologues of T4SS genes from Agrobacterium tumefaciens, while the other members in cag PAI still have no known function. We studied one of such proteins with unknown function, CagM, which was predicted to have a putative N-terminal signal sequence and at least three transmembrane helices. To determine the subcellular localization of CagM, we performed a cell fractionation procedure and produced rabbit anti-CagM polyclonal antibodies for immunoblotting assays. Furthermore, we generated an isogenic ΔcagM mutant to investigate the ability of CagA translocation compared with the wild-type NCTC 11637 strain using GES-1 and MKN-45 cell infection experiments. Our results indicated that CagM was mainly located in the bacterial membrane, partially located in the periplasm, and essential for CagA translocation both in GES-1 and MKN-45 cells, which suggested that CagM was one of the core members of Cag T4SS and localized in the transmembrane channel.
authors.affiliation: School of Medical Science and Laboratory Medicine, Jiangsu University, Zhenjiang, 212013, Jiangsu, China, tclingfeng@163.com.
authors.forename: Feng
authors.initials: F
authors.lastname: Ling
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wang
authors.forename: DongFang
authors.initials: D
authors.lastname: Dai
authors.forename: Min
authors.initials: M
authors.lastname: Yu
authors.forename: Cheng
authors.initials: C
authors.lastname: Chen
authors.forename: Jingyi
authors.initials: J
authors.lastname: Qian
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Ding
authors.forename: Xian Wei
authors.initials: XW
authors.lastname: Guan
authors.forename: Shihe
authors.initials: S
authors.lastname: Shao
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D015870:Gene Expression; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D021381:Protein Transport
chemical_list: D001426:Bacterial Proteins; D007473:Ion Channels