Analysis of the operating mechanism of BepA involved in the biosynthesis of bacterial outer membrane LPS translocon

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K06136
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 43030:Functional biochemistry-related
• Research Institution: Yamagata Prefectural Yonezawa University of Nutrition Sciences (2020); Morioka College (2018-2019)
• Principal Investigator: Narita Shin-ichiro 山形県立米沢栄養大学, 健康栄養学部, 教授 (30338751)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 細胞内タンパク質分解 / 表層ストレス応答 / 細菌細胞表層 / プロテアーゼ / シャペロン / 外膜タンパク質

Outline of Final Research Achievements

Outer membrane of gram-negative bacteria contains β-barreled outer membrane proteins. An Escherichia coli periplasmic protein BepA contributes to the maintenance of the structure and quality of the outer membrane by promoting the assembly of outer membrane proteins through its chaperone-like activity, and by degrading and removing abnormal outer membrane proteins through its protease activity. To elucidate the mechanism by which BepA discriminate between outer membrane proteins to be assembled and those to be degraded, we constructed BepA mutants and analyzed their function. We found that the α9/H246 loop located near the protease active site of BepA normally suppresses the protease activity of BepA, and that the reversible conformational change of this loop induces the protease activity of BepA to degrade outer membrane proteins.

Free Research Field

機能生物化学

Academic Significance and Societal Importance of the Research Achievements

本研究では、大腸菌プロテアーゼによる外膜の機能維持の分子機構をアミノ酸残基レベルで解明した。ヒスチジン残基を介してプロテアーゼ活性が可逆的に制御されるという新たな活性調節機構を解明したことにより、細胞内タンパク質の品質維持においてプロテアーゼとシャペロンの働きがどのように制御されているかという、大腸菌からヒトまで共通する普遍的なテーマに対して新たな知見を提供することができた。