| Project/Area Number |
16K07681
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Applied microbiology
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| Research Institution | Kindai University |
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Principal Investigator |
Eguchi Yoko 近畿大学, 生物理工学部, 講師 (30757422)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2016: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 酸応答 / ヒスチジンキナーゼ / EvgS / センサー / 酸化還元 / 環境・細胞応答 / シグナル伝達 / 酸耐性誘導機構 |
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| Outline of Final Research Achievements |
EvgS is an acid pH-responding sensor in Escherichia coli. When this sensor is activated by mild acidic pH (4.5 - 6), expression of various acid resistance genes is induced and renders the cells acid resistant. Since addition of organic acids to the culture or proliferation under anaerobic environment inhibited EvgS activation even when the culture was adjusted to pH5.7, our initial hypothesis was that a pH gradient across the cell membrane was required for EvgS activation. However, addition of a small amount of organic acid, that did not disrupt the pH gradient, also inactivated EvgS. Thus, other factors beside the disruption of the pH gradient were involved in the EvgS inactivation. Furthermore, inactivation of EvgS under anaerobic condition was caused by the lack of oxidized ubiquinone within the cell membrane. We propose a novel EvgS activation model that requires oxidized ubiquinones for the formation of disulfide bonds between the cysteine residues in the EvgS PAS domain.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では大腸菌の酸性pHセンサーEvgSの活性化機構を検討した。病原性大腸菌は優れた酸耐性能を有しており、そのため少数の菌数でも食中毒などを引き起こすものと考えられている。EvgSは酸耐性化に関わる遺伝子群の発現制御を行い、その活性化機構を解明することは食中毒予防に貢献する。本研究ではEvgSが酸性pH以外に酸化還元状態にも応答することを見出した。さらに、酢酸や安息香酸などの有機酸によってEvgSが不活化するのは、単に細胞内外でのpH勾配の喪失では説明できないことが判明した。有機酸によるEvgSの不活化機構をさらに解析することで、細菌に対する有機酸の影響のより深い理解が期待される。
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