ジャーナル: Science / 年: 2019 タイトル: A human postcatalytic spliceosome structure reveals essential roles of metazoan factors for exon ligation. 著者: Sebastian M Fica / Chris Oubridge / Max E Wilkinson / Andrew J Newman / Kiyoshi Nagai / 要旨: During exon ligation, the spliceosome recognizes the 3'-splice site (3'SS) of precursor messenger RNA (pre-mRNA) through non-Watson-Crick pairing with the 5'SS and the branch adenosine, in a ...During exon ligation, the spliceosome recognizes the 3'-splice site (3'SS) of precursor messenger RNA (pre-mRNA) through non-Watson-Crick pairing with the 5'SS and the branch adenosine, in a conformation stabilized by Prp18 and Prp8. Here we present the 3.3-angstrom cryo-electron microscopy structure of a human postcatalytic spliceosome just after exon ligation. The 3'SS docks at the active site through conserved RNA interactions in the absence of Prp18. Unexpectedly, the metazoan-specific FAM32A directly bridges the 5'-exon and intron 3'SS of pre-mRNA and promotes exon ligation, as shown by functional assays. CACTIN, SDE2, and NKAP-factors implicated in alternative splicing-further stabilize the catalytic conformation of the spliceosome during exon ligation. Together these four proteins act as exon ligation factors. Our study reveals how the human spliceosome has co-opted additional proteins to modulate a conserved RNA-based mechanism for 3'SS selection and to potentially fine-tune alternative splicing at the exon ligation stage.
超分子 #1: Human post-catalytic P complex spliceosome
超分子
名称: Human post-catalytic P complex spliceosome / タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: #1-#44
由来(天然)
生物種: Homo sapiens (ヒト)
分子量
理論値: 3.0 MDa
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実験情報
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構造解析
手法
クライオ電子顕微鏡法
解析
単粒子再構成法
試料の集合状態
particle
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試料調製
濃度
1 mg/mL
緩衝液
pH: 7.9 構成要素:
濃度
名称
式
20.0 mM
HEPES
100.0 mM
KCl
0.2 mM
EDTA
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK III 詳細: 3 uL sample was applied to the grid, left for 25s, then blotted for 2.5-3.5s and immediately plunged into liquid ethane..