Analysis of membrane vesicle production in gram negative bacteria

• Project/Area Number: 17K08825
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Bacteriology (including mycology)
• Research Institution: Kyoto University (2019); University of Miyazaki (2017-2018)
• Principal Investigator: Murase Kazunori 京都大学, 医学研究科, 助教 (40710869)
• Co-Investigator(Kenkyū-buntansha): 相川 知宏 京都大学, 医学研究科, 助教 (70725499) ; 白石 宗 札幌医科大学, 医学部, 助教 (70725168)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 外膜小胞 / 病原性細菌 / 宿主細胞の免疫応答 / エンドサイトーシス / ワクチン

Outline of Final Research Achievements

In this study, we performed sugar-chain structure analysis for lipopolysaccharide (LPS) of bacterial cells expressing hlyF gene, and demonstrated that HlyF is involved in the structural modification of lipid A (a part of LPS), suggesting the induction of OMV production in bacteria.
We also found that OMV induce host immune response (IL-8, IL-18, and IL-1β). Inflammasome activation is a multistep process leading to processing and secretion of mature IL-1β and IL-18. Our result suggests that bacteria-derived OMVs contribute to the inflammasome activation.

Academic Significance and Societal Importance of the Research Achievements

細菌が産生する外膜小胞（OMV）は、内包する種々の細菌由来分子を介して、宿主への病原性発揮機構の一部を担うことが既に報告されており、今回得られたLPSの構造的な変化がOMVの産生誘導に関与するという知見は、他の細菌においても多様な病原メカニズムを解明する上で、非常に重要な知見と考えられる。また、その一方で、本研究成果の一部として得られたOMVによる宿主細胞での免疫応答およびインフラマソーム形成への関与は、種々の細菌感染とそれに伴う病態変化を結びつける基盤的な知見と成り得るものである。さらに、これらの成果は細菌感染症に対するワクチン開発への将来的な応用に繋がると期待される。

Research Products

• [Int'l Joint Research] INSERM/INRA(フランス)
• [Journal Article] TBC1D9 regulates TBK1 activation through Ca 2+ signaling in selective autophagy. (2020)
  • Author(s): Nozawa T, Sano S, Minowa-Nozawa A, Toh H, Nakajima S, Murase K, Aikawa C, Nakagawa I
  • Journal Title: Nature Communications Volume: 11(1) Pages: 1-16
  • NAID: 120006840172
  • Peer Reviewed
• [Journal Article] Characterization of pig saliva as the major natural habitat of Streptococcus suis by analyzing oral, fecal, vaginal, and environmental microbiota (2019)
  • Author(s): Murase K, Watanabe T, Arai S, Kim H, Tohya M, Ishida-Kuroki K, Vo TH, Nguyen TPB, Nakagawa I, Osawa R, Nguyen NH, Sekizaki T
  • Journal Title: PLoS One Volume: 14(4)
  • NAID: 120006634676
  • Peer Reviewed
• [Journal Article] Phylogenetic relationship of prophages is affected by CRISPR selection in Group A Streptococcus (2019)
  • Author(s): Yamada S, Shibasaki M, Murase K, Watanabe T, Aikawa C, Nozawa T, Nakagawa I. Phylogenetic relationship of prophages is affected by CRISPR selection in Group A Streptococcus
  • Journal Title: BMC Microbiology Volume: 19(1) Pages: 24-24
  • Peer Reviewed
• [Presentation] Proteome analysis of extracellular vesicles produced by Streptococcus pyogenes (2020)
  • Author(s): 村瀬一典, 相川知宏, 中武彩子, 菊地泰生, 野澤孝志, 中川一路
  • Organizer: 第93回日本細菌学会総会（2020）
• [Presentation] COMPREHENSIVE PHYLOGENETIC ANALYSIS AND GENOME DYNAMICS OF O-SEROGROUP REFERENCE STRAINS IN VIBRIO CHOLEARE (2019)
  • Author(s): Kazunori Murase, Masatomo Morita, Taichiro Takemura, Eiji Arakawa, Hidemasa Izumiya, Ichiro Nakagawa, Taisei Kikuchi, Makoto Ohnishi
  • Organizer: 8th Congress of European Microbiologists (FEMS 2019)
  • Int'l Joint Research