ジャーナル: Cell / 年: 2005 タイトル: The cryo-EM structure of a translation initiation complex from Escherichia coli. 著者: Gregory S Allen / Andrey Zavialov / Richard Gursky / Måns Ehrenberg / Joachim Frank / 要旨: The 70S ribosome and its complement of factors required for initiation of translation in E. coli were purified separately and reassembled in vitro with GDPNP, producing a stable initiation complex ...The 70S ribosome and its complement of factors required for initiation of translation in E. coli were purified separately and reassembled in vitro with GDPNP, producing a stable initiation complex (IC) stalled after 70S assembly. We have obtained a cryo-EM reconstruction of the IC showing IF2*GDPNP at the intersubunit cleft of the 70S ribosome. IF2*GDPNP contacts the 30S and 50S subunits as well as fMet-tRNA(fMet). IF2 here adopts a conformation radically different from that seen in the recent crystal structure of IF2. The C-terminal domain of IF2 binds to the single-stranded portion of fMet-tRNA(fMet), thereby forcing the tRNA into a novel orientation at the P site. The GTP binding domain of IF2 binds to the GTPase-associated center of the 50S subunit in a manner similar to EF-G and EF-Tu. Additionally, we present evidence for the localization of IF1, IF3, one C-terminal domain of L7/L12, and the N-terminal domain of IF2 in the initiation complex.
全体 : E. coli 70S, IF1, IF3, mRNA, fMet-tRNA, and IF2-GDPNP
全体
名称: E. coli 70S, IF1, IF3, mRNA, fMet-tRNA, and IF2-GDPNP
要素
試料: E. coli 70S, IF1, IF3, mRNA, fMet-tRNA, and IF2-GDPNP
複合体: 30S
複合体: 50s
RNA: fmet-tRNA
RNA: mRNA
タンパク質・ペプチド: beta IF2-GDPNP
タンパク質・ペプチド: IF1
タンパク質・ペプチド: IF3
-
超分子 #1000: E. coli 70S, IF1, IF3, mRNA, fMet-tRNA, and IF2-GDPNP
超分子
名称: E. coli 70S, IF1, IF3, mRNA, fMet-tRNA, and IF2-GDPNP タイプ: sample / ID: 1000 / 集合状態: One of each component binds to the 70S / Number unique components: 7
automated particle picking followed by manual verification
CTF補正
詳細: defocus groups
最終 再構成
想定した対称性 - 点群: C1 (非対称) / アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 13.8 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: SPIDER 詳細: The falloff of Fourier amplitudes toward higher spatial frequencies was corrected using the x-ray solution scattering intensity distribution of 70S ribosomes from E. coli during each round of refinement. 使用した粒子像数: 20283
-
原子モデル構築 1
ソフトウェア
名称: RSRef
詳細
Protocol: real-space refinement of rigid bodies. IF2 and IF1 were initially fit by hand in O then refined by RSRef
精密化
空間: REAL / プロトコル: RIGID BODY FIT / 当てはまり具合の基準: correlation coefficient
得られたモデル
PDB-1zo1: IF2, IF1, and tRNA fitted to cryo-EM data OF E. COLI 70S initiation complex
PDB-1zo3: The P-site and P/E-site tRNA structures fitted to P/I site codon.