イーストのSir2タンパク質に含まれる酵素活性で,遺伝子の静止に不可欠です

J C Tanny¹, G J Dowd, J Huang

¹Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.

Cell

|January 5, 2000

まとめ

転写サイレンシングに不可欠なSir2タンパク質は,ADP-リボシルトランスフェラーゼとして機能する. 遺伝子の静止に不可欠なこの酵素活性は,保存されたヒスティジン残基に依存しています.

科学分野:

バイオケミストリーバイオケミストリー
分子生物学は分子生物学である.
遺伝学遺伝学とは

背景:

Sir2タンパク質は種間で保存され,転写サイレンシングに関与することが知られている.
その正確な分子機能は,その重要性にもかかわらず,捉え難いままです.

研究の目的:

Sir2タンパク質の未知の機能を明らかにするために.
転写サイレンシングにおけるSir2の酵素活性およびin vivoの役割を調査する.

主な方法:

ラベル付けされたニコチナミドアデニン・ディヌクレオチド (NAD+) を用いたインビトロ酵素分析.
抗モノ-ADP-リボース抗体を用いたタンパク質改変分析.
Sir2.で保存されたヒスティジン残基のサイト指向型変異.
野生型および変異したSir2タンパク質の染色体関連性研究.

主要な成果:

Sir2は,INVITROでNAD+から自己およびヒストンにリン酸を転送することが示されました.
Sir2はADP-リボシルトランスフェラーゼ活性を発現し,自らを改変し,抗モノ-ADP-リボス抗体によって認識される製品を形成する.
保存されたヒスティジン残基の変異により,Sir2の酵素活性と vivo 静音機能が廃止されました.
変異したSir2タンパク質は,クロマチンと静音因子との関連性を維持した.

結論:

Sir2は,ADP-リボシルトランスフェラーゼの重要な活性を持っています.
この酵素活性は,転写遺伝子の静止におけるSir2タンパク質の役割に不可欠である.
保存されたヒスティジンの残留は,Sir2の酵素機能と静止における生物学的役割の両方にとって不可欠です.

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