バクテリアの生物多様性は,CRISPRベースのファグ耐性の進化を促しています

Ellinor O Alseth¹, Elizabeth Pursey², Adela M Luján³

¹Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn Campus, Penryn, UK. eao210@exeter.ac.uk.

Nature

|October 25, 2019

まとめ

バクテリアのコミュニティは CRISPR-Cas 免疫の進化を促します複雑な環境では細菌はファグ耐性に対する受容体変異よりも CRISPR を好み毒性に影響します

科学分野:

微生物学
進化生物学
遺伝学

背景:

CRISPR-Casシステムは自然界で急速に進化する細菌に適応免疫を提供します
バクテリアのファグ耐性には,実験室での受容体変異が伴うことが多いので,自然進化とは対照的です.
細菌の免疫系の進化を形作る環境生物学的複雑性の役割は十分に研究されていない.

研究の目的:

自然環境と実験室環境で CRISPR による免疫の進化が異なる原因を調査する
他の病原体の存在がファージに対するバクテリアの耐性戦略にどのように影響するか理解する.
バクテリアの毒性に対する異なる耐性メカニズムの影響を調べる.

主な方法:

機会性病原体である Pseudomonas aeruginosa とそのファグである DMS3vir を利用した.
生物学的複雑性の異なるファグ受容体の変異とCRISPRベースの耐性の進化を比較した.
異なる進化経路でP. aeruginosaのフィットネス・トレードオフと毒性を評価した.

主要な成果:

他の病原体との共存は,P. aeruginosaのファグ受容体変異に対するフィットネストレードオフを拡大する.
この増幅は,受容体ベースの抵抗よりもCRISPR- Casの適応免疫の進化を好む.
細菌の毒性は,表面的な耐性メカニズムが進化したときにのみ弱まりました.

結論:

微生物コミュニティにおける生物学的複雑性は,細菌のCRISPR-Cas免疫の進化の主要な原動力である.
細菌の防御戦略のバランスには環境要因が大きく影響します
バクテリアの免疫の進化は,バクテリアの健康性と病原性にも直接的な影響を及ぼします.

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