Saccharomyces cerevisiaeにおける円形の染色体形成によるヒストン遺伝子の増幅

Diana E Libuda¹, Fred Winston

¹Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA.

Nature

|October 27, 2006

まとめ

ヒストンH2A-H2B遺伝子 (HTA1-HTB1) が酵母で削除されると,細胞はゲノムの完全性を維持するために新しい円形の染色体を作り,残りのヒストン遺伝子 (HTA2-HTB2) を増幅します.

科学分野:

分子生物学は分子生物学である.
遺伝学遺伝学とは
イースト生物学イースト生物学

背景:

ヒストンのレベルは,転写と染色体分離を含む基本的な細胞プロセスに不可欠です.
イースト (Saccharomyces cerevisiae) では,ヒストンH2AとH2Bは,HTA1-HTB1とHTA2-HTB2.2.という2つの遺伝子ペアによってコードされます.
HTA1-HTB1による転写補償は,HTA2-HTB2が削除されたときに発生することが以前から知られていた.

研究の目的:

転写調節を超えたヒストン遺伝子用量補償の代替メカニズムを調査する.
HTA1-HTB1が削除されたときにヒストン遺伝子のコピー番号が維持されるプロセスを解明する.

主な方法:

Saccharomyces cerevisiaeにおけるHTA1-HTB1遺伝子ペアの削除である.
特にTy1レトロトランポゾンを含むDNA複製および再結合の分析.
分子技術を用いて,新たに形成された円形の染色体の特徴づけ.

主要な成果:

HTA1-HTB1の削除は,単なる転写調整ではなく,遺伝子複製数の補償を誘発する.
HTA2-HTB2,HHT1-HHF1 (ヒストーンH3-H4ロカス),セントロメア,複製起源を含む新しい小さな円形の染色体が形成されます.
隣接するTy1要素の再結合により,この増幅ヒストン遺伝子を含む染色体が形成され, hta1-htb1Delta変異体ではより高い割合で発生します.

結論:

ヒストンH2AとH2Bのレベルが低下すると,異染色体DNA経由でヒストン遺伝子の増幅を刺激します.
この遺伝子増幅のメカニズムは,ヒストン遺伝子の投与量とゲノムの完全性の維持を保証します.
ヒストンの枯渇に反応する遺伝子複製数レベルでの新しい形態の用量補償を示しています.

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