CRISPRの適応バイアスは,外来DNAの獲得に対する好みを説明する

Asaf Levy¹, Moran G Goren², Ido Yosef²

¹Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.

Nature

|April 16, 2015

まとめ

CRISPR-Casシステムは,細菌の免疫のために外来DNAを取得します. スパッサー獲得は複製とDNAの断裂に依存し,ChiサイトとRecBCDは自己DNA統合を防ぐ.

科学分野:

微生物学微生物学とは
分子生物学は分子生物学である.
遺伝学遺伝学とは

背景:

CRISPR-Casシステムは,バクテリアのファグやプラズミドに対する適応免疫を提供します.
外来DNA断片をCRISPR配列に統合するスペーサー獲得は,この免疫にとって極めて重要です.
自己DNAよりも外来DNAからの優先取得を保証するメカニズムは不明のままである.

研究の目的:

CRISPR-Casシステムにおける外来DNAから優先的なスペーサー獲得のメカニズムを解明する.
スパッサー獲得時に自己染色体DNAを回避する要因を特定する.
CRISPR適応における複製とDNA修復経路の役割を理解する.

主な方法:

Escherichia coli.で探究されたスペーサー獲得.
複製の役割,DNAの断裂,Chi部位,およびRecBCD複合体の分析を行いました.
DNAの統合と修復を評価するために,遺伝学と分子生物学技術を活用した.

主要な成果:

スパッサー獲得はDNA複製に依存し,DNAの断裂によって促進される.
バクテリアの染色体上にあるチー部位は,自己DNAから限度スペーサーを取得したものです.
RecBCD複合体は,取得プロセス中に自己DNAの回避を媒介する.

結論:

E. coliにおけるCRISPR-Casのスペーサー獲得は,主に複製フォークにおける二重鎖の断絶のRecBCD媒介処理によって引き起こされる.
異種DNAに対する偏好は,Chiサイト分布と異種DNAにおけるより高い複製フォーク密度の組み合わせによって達成される.
このモデルは,高複製プラズミドとファグからスペースラーを取得するための観察された好みを説明します.

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