Molecular mechanism of Type III plasmid segregation

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K05774
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38020:Applied microbiology-related
• Research Institution: Yokohama City University
• Principal Investigator: Hayashi Ikuko 横浜市立大学, 生命医科学研究科, 准教授 (80464527)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 細胞骨格 / 微小管 / プラスミド / 微生物 / トレッドミル / 線維構造 / 遺伝子分配 / 毒素遺伝子

Outline of Final Research Achievements

The FtsZ/tubulin-like GTPase TubZ was identified as a segregation factor of the virulence plasmids pXO1 in Bacillus cereus and Bacillus anthracis. TubZ exhibits high GTPase activity and assembles into polymers both in vivo and in vitro, and its treadmilling movement is required for stable maintenance of the plasmid in the cell. We determined the crystal structures of two TubZ regulators, TubR and TubY. DNase 1 footprinting analysis demonstrated that TubR and TubY regulate the expression of their own genes and that TubY associates with the promoter region of tubRZ cooperatively with TubR. TubY belongs to the MerR family transcriptional factor which functions as a dimeric protein. However, the C-terminal domain of TubY forms a tetrameric parallel four-helix bundle that differs from the typical MerR proteins. Moreover, we have analyzed the dynamics of TubZ filament using high-speed atomic force microscopy and found that TubZ filaments exhibit both treadmilling and dynamic instability.

Free Research Field

生物物理

Academic Significance and Societal Importance of the Research Achievements

病原菌の毒素遺伝子の多くはプラスミドによって分配されることが知られる。本研究では炭疽症を引き起こす炭疽菌の近縁種セレウス菌の毒素プラスミドpXO1の分配に必須なTubZタンパク質とその制御因子について分子機構の解析を行った。TubZはプラスミド分配因子の中で最も最近に見つかったIII型の分配因子であり、その分子機構は明らかになっていない。本研究によってバクテリアのもつ新しい細胞骨格因子の分子制御機構を明らかにするとともに、病原性細菌に対する創薬の分子基盤を構築することができた。