エシェリキア・コライのCRISPR-Casシステムによる外来DNAの監視と処理

Sy Redding¹, Samuel H Sternberg², Myles Marshall³

¹Department of Chemistry, Columbia University, New York, NY 10027, USA.

Cell

|November 3, 2015

まとめ

バクテリアのCRISPR-Casシステムは外来DNAを見つけるためにカスケードを使います 2つの経路がある.一つはPAMでDNAを分解し,もう一つはCas1とCas2を含むPAM変異を処理する.

科学分野:

微生物学
分子生物学
遺伝学

背景:

CRISPR-Casシステムは,外来DNAに対するプロカリオットの適応免疫を提供します.
E. coli のカスケード複合体は外来DNAを結合し,Cas3核酵素を分解に誘導する.

研究の目的:

シングルモлекуラ画像を用いて外来DNAターゲットへのカスケードとCas3の結合を視覚化します.
CRISPR-CasによるDNA標的認識と分解の明確な経路を解明する.

主な方法:

単一分子イメージング技術が採用されました.
カスケードとCas3複合体によるDNA標的結合と分解の分析
経路決定におけるプロトスペーサー付近モチーフ (PAM) の役割の調査.

主要な成果:

2つの異なる経路が特定され,それはPAMの存在または欠如に依存しています.
PAMを含む標的は,DNA分解のために核酸活性Cas3を募集する.
PAM変異は,Cas1とCas2に依存する,ヌクレアース無活性Cas3を含む別の経路を誘発する.

結論:

カスケードの標的認識は DNAの分解を決定する
Cas1とCas2がCas3転位による新しいスペースアキビションを容易にするモデルがサポートされます.
これは,CRISPR-Casの適応免疫とDNA処理に関するメカニズム的な洞察を提供します.

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