トランポゾンでコードされた核酵素は,自己的な拡散を促進するためにガイドRNAを使用します

Chance Meers¹, Hoang C Le^2,1, Sanjana R Pesari^1,3

¹Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.

Nature

|September 27, 2023

まとめ

挿入配列は,トランポジション中にそれらの損失を防ぐためにTnpBとIscBタンパク質によってRNA誘導のDNA分裂を使用します. この古代のメカニズムはトランポゾン拡散に不可欠で CRISPR-Casの免疫よりも古いものです

科学分野:

微生物学
分子生物学
遺伝学

背景:

挿入配列 (IS) は,活性化遺伝子をコードする細菌の移植可能な要素である.
IS200/IS605ファミリーは,TnpAトランスポーゼを"剥きとペースト"トランスポーゼに使用します.
Cas12とCas9に関連したTnpBとIscBタンパク質は,RNA誘導DNAエンドヌクレアース活性を持っています.

研究の目的:

ISトランスポーゼーションにおけるTnpBとIscBRNA誘導DNAエンドヌクレアスの生物学的役割を調査する.
TnpBとIscBがTnpAによるトランポゾン損失を防ぐかどうかを判断する.
CRISPR-Casシステムとの関係でRNA誘導DNA分裂の進化的起源を探求する.

主な方法:

Geobacillus stearothermophilusのTnpBとIscBのオーソログをコードする挿入配列を研究した.
トランポゾン動員のためのTnpAトランポザースの活性評価
TnpBとIscB核酸によるドナー関節の標的化を分析した.
TnpAとTnpBの共同発現とTnpA単独の保持を比較した.

主要な成果:

単一のTnpAトランスポゼは,関連する挿入配列全体で広範な活性を示した.
RNA誘導のTnpBとIscB核酵素は,再結合されたトランポゾンドナーの関節を効率的に割った.
TnpAのみと比較して,TnpBとTnpAの共発はトランポゾン保持を著しく増加させた.
TnpAとTnpBの併用により,TnpB単独での再結合頻度が増加しました.

結論:

TnpBとIscBによるRNA誘導のDNA分裂は,TnpA媒介によるトランポゾン損失を防止するために重要である.
この活動により転置可能な要素の利己的な継承と拡散が保証されます
RNA誘導のDNA分裂は,後にCRISPR-Cas適応免疫に適応した原始的な生化学的機能を表しています.

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