ジャーナル: EMBO J / 年: 2002 タイトル: Cryo-EM reveals an active role for aminoacyl-tRNA in the accommodation process. 著者: Mikel Valle / Jayati Sengupta / Neil K Swami / Robert A Grassucci / Nils Burkhardt / Knud H Nierhaus / Rajendra K Agrawal / Joachim Frank / 要旨: During the elongation cycle of protein biosynthesis, the specific amino acid coded for by the mRNA is delivered by a complex that is comprised of the cognate aminoacyl-tRNA, elongation factor Tu and ...During the elongation cycle of protein biosynthesis, the specific amino acid coded for by the mRNA is delivered by a complex that is comprised of the cognate aminoacyl-tRNA, elongation factor Tu and GTP. As this ternary complex binds to the ribosome, the anticodon end of the tRNA reaches the decoding center in the 30S subunit. Here we present the cryo- electron microscopy (EM) study of an Escherichia coli 70S ribosome-bound ternary complex stalled with an antibiotic, kirromycin. In the cryo-EM map the anticodon arm of the tRNA presents a new conformation that appears to facilitate the initial codon-anticodon interaction. Furthermore, the elbow region of the tRNA is seen to contact the GTPase-associated center on the 50S subunit of the ribosome, suggesting an active role of the tRNA in the transmission of the signal prompting the GTP hydrolysis upon codon recognition.
名称: aa-tRNA / タイプ: rna / ID: 1 詳細: 14 pmol; fMet-tRNA(fMet) at the P site and Phe-tRNA(phe) at the A site 分類: TRANSFER / Structure: DOUBLE HELIX / Synthetic?: No
名称: GDP / タイプ: ligand / ID: 3 詳細: 8 ul of 2.5mM; [Alpha-(32)P]GTP The radioactivity contributed by the Alpha-(32)P moiety of the GDP served to calculate a ~50% occupancy for the elongation factor. 組換発現: No
由来(天然)
生物種: synthetic construct (人工物)
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分子 #4: kirromycin
分子
名称: kirromycin / タイプ: ligand / ID: 4 / 詳細: 3 ul of 100 mM; antibiotic / 組換発現: No
pH: 7.5 詳細: 20 mM HEPES-KOH, 6mM MgCl2, 150mM NH4Cl, 4mM 2-metcaptoethanol, 0.05 mM spermine and 2 mM spermidine
凍結
凍結剤: ETHANE / チャンバー内湿度: 30 % / チャンバー内温度: 93 K / 装置: HOMEMADE PLUNGER / 詳細: Vitrification instrument: two side blotting plunger / 手法: Blot for 2 seconds before plunging
Protocol: Rigid Body. The EF-Tu domains were separately fitted by manual docking using program O (pdb codes for fitted coordinates: 1LS2, 1LU3)
精密化
プロトコル: RIGID BODY FIT 当てはまり具合の基準: cross correlation coefficient
得られたモデル
PDB-1ls2: Fitting of EF-Tu and tRNA in the Low Resolution Cryo-EM Map of an EF-Tu Ternary Complex (GDP and Kirromycin) Bound to E. coli 70S Ribosome
PDB-1lu3: Separate Fitting of the Anticodon Loop Region of tRNA (nucleotide 26-42) in the Low Resolution Cryo-EM Map of an EF-Tu Ternary Complex (GDP and Kirromycin) Bound to E. coli 70S Ribosome