Functional analysis of Type IX secretion system using nano scale biomolecule imaging approach

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K17085
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Morphological basic dentistry
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: Satoshi Shibata 沖縄科学技術大学院大学, 生体分子電子顕微鏡解析ユニット, 研究員 (30725057)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 分泌装置 / 電子顕微鏡 / 病原性細菌 / 滑走細菌 / T9SS / 歯周病

Outline of Final Research Achievements

The type IX secretion system (T9SS) is unique to phylum Bacteroidetes bacteria and involved in the secretion of pathogenic proteins and gliding motility. To understand these mechanisms of T9SS, we tried to identify the structure of T9SS complex.
In this study, we visualized the ring-like pore structure of T9SS located in the outer membrane in the oral pathogen Porphyromonas gingivalis. In addition, we established a novel rapid freezing method using silica beads. Furthermore, we clarified the existence of helical gliding machinery located inside the outer membrane of the soil bacterium Flavobacterium johnsoniae using various imaging techniques including cryo-electron microscopy. Based on the gliding machinery results a new gliding mechanism was proposed.

Free Research Field

生体分子科学

Academic Significance and Societal Importance of the Research Achievements

生命機能のメカニズムを解明する上で、各々の機能を担う生体超分子の立体構造の情報は欠かせない。T9SSはバクテロデーテス細菌にとって必須であり、病原性にも重要な役割を担う。研究成果はT9SSの構造、機能の理解という細菌学に新たな知見を与えるだけでなく、T9SSを標的とした分泌阻害、滑走運動阻害剤など感染防除法開発への足がかりになることが期待できる。また、新しい急速凍結法の提案は生体分子イメージング技術の発展にも寄与する。