ジャーナル: J Biol Chem / 年: 2012 タイトル: Structural insights into methyltransferase KsgA function in 30S ribosomal subunit biogenesis. 著者: Daniel Boehringer / Heather C O'Farrell / Jason P Rife / Nenad Ban / 要旨: The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3'-terminal ...The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3'-terminal helix 45 of the 16 S ribosomal RNA (rRNA). KsgA recognizes its substrate adenosine residues only in the context of a near mature 30S subunit and is required for the efficient processing of the rRNA termini during ribosome biogenesis. Here, we present the cryo-EM structure of KsgA bound to a nonmethylated 30S ribosomal subunit. The structure reveals that KsgA binds to the 30S platform with the catalytic N-terminal domain interacting with substrate adenosine residues in helix 45 and the C-terminal domain making extensive contacts to helix 27 and helix 24. KsgA excludes the penultimate rRNA helix 44 from adopting its position in the mature 30S subunit, blocking the formation of the decoding site and subunit joining. We suggest that the activation of methyltransferase activity and subsequent dissociation of KsgA control conformational changes in helix 44 required for final rRNA processing and translation initiation.
全体 : Structure of the E. coli 30S ribosomal subunit from a ksgA deleti...
全体
名称: Structure of the E. coli 30S ribosomal subunit from a ksgA deletion strain in the conformation obtained at high magnesium concentrations.
要素
試料: Structure of the E. coli 30S ribosomal subunit from a ksgA deletion strain in the conformation obtained at high magnesium concentrations.
複合体: E. coli 30S ribosomal subunit
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超分子 #1000: Structure of the E. coli 30S ribosomal subunit from a ksgA deleti...
超分子
名称: Structure of the E. coli 30S ribosomal subunit from a ksgA deletion strain in the conformation obtained at high magnesium concentrations. タイプ: sample / ID: 1000 詳細: Translationally inactive 30S ribosomal subunits from a magnesium depleted sample were reactivated by incubation at high magnesium concentrations. 集合状態: Monomer / Number unique components: 1
分子量
実験値: 790 KDa / 理論値: 790 KDa
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超分子 #1: E. coli 30S ribosomal subunit
超分子
名称: E. coli 30S ribosomal subunit / タイプ: complex / ID: 1 / Name.synonym: small ribosomal subunit 詳細: 30S ribosomal subunits lacking the methylation at A1518 and A1519 組換発現: Yes / Ribosome-details: ribosome-prokaryote: SSU 30S
由来(天然)
生物種: Escherichia coli (大腸菌)
組換発現
生物種: Escherichia coli (大腸菌)
分子量
実験値: 790 KDa / 理論値: 790 KDa
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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
緩衝液
pH: 7.6 詳細: 100 mM NH4Cl, 20 mM MgCl2, 20 mM HEPES/KOH pH 7.6, 3 mM DTT
グリッド
詳細: Quantifoil 200 mesh copper
凍結
凍結剤: ETHANE / 装置: OTHER
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電子顕微鏡法
顕微鏡
FEI TECNAI 20
詳細
Semi-automatic data acquisition with SerialEM script