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2020 Fiscal Year Final Research Report

Molecular evolution of hemolysins involved in oral streptococcal pathogenicity

Research Project

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Project/Area Number 18K09552
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 57020:Oral pathobiological science-related
Research InstitutionThe University of Tokushima

Principal Investigator

NAGAMUNE Hideaki  徳島大学, 大学院社会産業理工学研究部(生物資源産業学域), 教授 (40189163)

Co-Investigator(Kenkyū-buntansha) 田端 厚之  徳島大学, 大学院社会産業理工学研究部(生物資源産業学域), 講師 (10432767)
友安 俊文  徳島大学, 大学院社会産業理工学研究部(生物資源産業学域), 准教授 (20323404)
Project Period (FY) 2018-04-01 – 2021-03-31
Keywords口腔連鎖球菌 / 溶血毒素 / 病原性 / 分子進化 / 細胞付着因子
Outline of Final Research Achievements

Analysis on the gene distribution of hemolysin (HL) and its related molecules in four groups of oral streptococci revealed that streptolysin S-related toxin (SLS) and cholesterol-dependent cytolysin family (CDC) were distributed in only anginosus group streptococci (AGS) and in two groups of AGS and mitis group streptococci (MGS), respectively. It was also revealed that CDC particularly showed significant structural diversity in MGS and evolved into hybrid molecules, such as ExD-CDC showing both hemolytic activity and facilitating activity of adhesion between host cells and a cell-adhesion factor with lipase activity, mitilectin (MLC). Furthermore, the coexistence of MLC and CDC including ExD-CDC was frequently found in MGS species. Therefore, it was suggested that these evolved HL molecules collaboratively increase the pathgenicity of MGS strains possessing both MLC and CDC such as ExD-CDC.

Free Research Field

細菌学

Academic Significance and Societal Importance of the Research Achievements

近年の分類学や菌種同定技術の発達により,従来は弱毒菌とされてきた口腔連鎖球菌の菌種の中にも,ヒトに種々の感染症を起こす菌株群が頻見されることが分かってきている。しかしなぜ,同菌種の弱毒性株と病原性が異なるかについては,詳細な解析がほとんど進んでいなかった。今回,多くの病原菌の主要病原因子と認識されているHLに着目し,その分布や機能的分子進化の観点から解析を進め,HL分子種の獲得・重複・機能的多様化が起こることで口腔連鎖球菌が病原性化する方向に進化することを見いだしたことが本研究の大きな学術的意義である。またその知見はこれら菌群による感染症の臨床治療にも有用な情報となるため,社会的意義も大きい。

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Published: 2022-01-27  

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