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Increased Outer Membrane Vesicle Formation in a Helicobacter pylori tolB Mutant
Author(s) -
Turner Lorinda,
Praszkier Judyta,
Hutton Melanie L.,
Steer David,
Ramm Georg,
KaparakisLiaskos Maria,
Ferrero Richard L.
Publication year - 2015
Publication title -
helicobacter
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.206
H-Index - 79
eISSN - 1523-5378
pISSN - 1083-4389
DOI - 10.1111/hel.12196
Subject(s) - bacterial outer membrane , microbiology and biotechnology , virulence , biology , mutant , bacteria , helicobacter pylori , cell wall , pathogenicity island , flagellum , cell envelope , escherichia coli , gene , biochemistry , genetics
Background Multiple studies have established the importance of the tol‐pal gene cluster in bacterial cell membrane integrity and outer membrane vesicle (OMV) formation in Escherichia coli . In contrast, the functions of Tol‐Pal proteins in pathogenic organisms, including those of the Epsilonproteobacteria , remain poorly if at all defined. The aim of this study was to characterize the roles of two key components of the Tol‐Pal system, TolB and Pal, in OMV formation in the pathogenic bacterium, Helicobacter pylori . Methods H. pylori Δ tolB , Δ pal and Δ tolBpal mutants, as well as complemented strains, were generated and assessed for changes in morphology and OMV production by scanning electron microscopy and enzyme‐linked immunoassay (ELISA), respectively. The protein content and pro‐inflammatory properties of OMVs were determined by mass spectroscopy and interleukin‐8 (IL‐8) ELISA on culture supernatants from OMV‐stimulated cells, respectively. Results H. pylori Δ tolB and Δ pal bacteria exhibited aberrant cell morphology and/or flagella biosynthesis. Importantly, the disruption of H. pylori tolB but not pal resulted in a significant increase in OMV production. The OMVs from H. pylori Δ tolB and Δ pal bacteria harbored many of the major outer membrane and virulence proteins observed in wild‐type (WT) OMVs. Interestingly, Δ tolB , Δ pal and Δ tolBpal OMVs induced significantly higher levels of IL‐8 production by host cells, compared with WT OMVs. Conclusions This work demonstrates that TolB and Pal are important for membrane integrity in H. pylori . Moreover, it shows how H. pylori tolB ‐ pal genes may be manipulated to develop “hypervesiculating” strains for vaccine purposes.