Helicobacter pylori Growth Stage Determines the Size, Protein Composition and Preferential Cargo Packaging of Outer Membrane Vesicles.

Gram-negative bacteria release outer membrane vesicles (OMVs) as part of their normal growth that contain a range of cargo from their parent bacterium, including DNA, RNA, and proteins. The protein content of OMVs is suggested to be similar in composition to various sub-cellular locations of their parent bacterium. However, very little is known regarding the effect of bacterial growth stage on the size, content and selective packaging of proteins into OMVs. In this study, we examined the global proteome of Helicobacter pylori and their OMVs throughout bacterial growth to determine if bacterial growth stage affected OMV cargo composition. Analysis of OMVs produced by H. pylori revealed that bacterial growth stage affected the size, composition and selection of protein cargo into OMVs. Proteomic analysis identified that the proteome of H. pylori OMVs was vastly different throughout bacterial growth and that OMVs contained a range of proteins compared to their parent bacteria. In addition, bacterial growth stage affected the ability of OMVs to induce the production of IL-8 by human epithelial cells. Therefore, our findings identify that the size, proteome and immunogenicity of OMVs produced during various stages of bacterial growth is not comparable. Collectively, these findings highlight the importance of considering the bacterial growth stage from which OMVs are isolated from, as this will impact their size, protein composition and ultimately their biological functions. This article is protected by copyright. All rights reserved.