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Crystal structure of CagV, the Helicobacter pylori homologue of the T4 SS protein VirB8
Author(s) -
Wu Xiuling,
Zhao Yanhe,
Sun Lifang,
Jiang Meiqin,
Wang Qin,
Wang QianChao,
Yang Wendi,
Wu Yunkun
Publication year - 2019
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14971
Subject(s) - periplasmic space , helicobacter pylori , chemistry , secretion , dimer , mutagenesis , microbiology and biotechnology , biology , biochemistry , mutant , escherichia coli , gene , genetics , organic chemistry
The VirB/D type IV secretion system (T4 SS ) plays an essential role in materials transport between host cells and pathogenic Helicobacter pylori and is considered the major pathogenic mediator of H. pylori ‐associated gastric disease. VirB8, an inner membrane protein that interacts with many other proteins, is a crucial component for secretory function. Here, we present a crystal structure of the periplasmic domain of CagV, the VirB8 counterpart in the H. pylori Cag‐T4 SS . The structure reveals a fold similar to that of other VirB8 members except for the absence of the α5 helix, a discontinuous β1 strand, a larger angle between the α2 and α3 helices, a more hydrophobic surface groove, but exhibits a different dimer interface. Whether the dimerization occurs in solution was proved by mutagenesis, size‐exclusion chromatography and cross‐linking assays. Unlike the classical dimerization mode, the interface of the CagV dimer is principally formed by several hydrogen bonds, which indicates instability of dimerization. The structure here demonstrates the difference in dimerization among VirB8 homologues and indicates the considerable compositional and functional diversity of them in T4 SS . Database Coordinates and structure factors have been deposited in the Protein Data Bank under accession codes 6IQT .