2019 Fiscal Year Final Research Report
Analysis of expression mechanisms and adherence functions of streptococcal pili(Fostering Joint International Research)
| Project/Area Number |
15KK0306
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| Research Category |
Fund for the Promotion of Joint International Research (Fostering Joint International Research)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Morphological basic dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
2016 – 2019
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| Keywords | レンサ球菌 / 線毛 |
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| Outline of Final Research Achievements |
Streptococcus pyogenes produces a variety of pili and thermosensitive expression of pilus genes was previously observed in a specific serotype strain. To reveal the mechanism involved, pilus expression analysis of clinical isolates was conducted. Thermosensitive pilus production was only observed in strains possessing the nra gene encoding a transcriptional regulator. Additionally, analysis using mutant strains indicated that the Nra protein is a positive regulator of pilus genes and showed a relationship of its intracellular level with pilus production. The translational efficiency of nra mRNA was increased when the temperature was decreased and a putative stem loop structure within the coding region of nra mRNA was also shown to be involved in that. Thus, during the initial infection step, S. pyogenes may adapt to the external body surface temperature, and modulate both the translational efficiency of nra and expression levels of pili required for initial adherence to host tissues.
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| Free Research Field |
細菌学
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| Academic Significance and Societal Importance of the Research Achievements |
化膿レンサ球菌の感染初期に機能する細菌因子の産生量を規定する仕組みとして，転写を促進する因子のmRNAが環境温度の変化により構造を変化させ，その翻訳が調節されることが推察された．環境温度を感知するmRNAの部位は，主に報告されてきた非翻訳領域ではなく，翻訳領域にあるという，本菌では初めて明らかにされたmRNAによる温度感知機構であった．さらに，臨床現場で用いられてきた化膿レンサ球菌のTタイピング法において低温培養が必要とされてきたが，その理由の一端が明らかになった．
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