Structural basis of l-tryptophan-dependent inhibition of release factor 2 by the TnaC arrest peptide.
Structural basis of l-tryptophan-dependent inhibition of release factor 2 by the TnaC arrest peptide.
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DOI：
10.1093/nar/gkab665
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发表时间：
2021-09-20
影响因子：
14.9
通讯作者：
Beckmann R
中科院分区：
文献类型：
--
作者：
Su T;Kudva R;Becker T;Buschauer R;Komar T;Berninghausen O;von Heijne G;Cheng J;Beckmann R
在大肠杆菌中，游离L-色氨酸(L-色氨酸)水平的升高通过抑制TNAC肽的终止来促进其翻译停滞。然而，在停滞的Tna C-核糖体-新生链状复合体的UGA终止密码子上，UGA特异性解码释放因子2(RF2)的翻译终止机制至今仍不明确。本研究提供了在没有RF2和存在RF2的情况下被TNAC停滞的核糖体的低温EM结构，平均分辨率分别为2.9%和3.5o。停滞的TNAC呈现出一种独特的构象，由两个小的α-螺旋与肽出口隧道中的残基一起作用来配位单个L-色氨酸分子。此外，虽然肽基转移酶中心(PTC)被锁定在允许RF2采用其在核糖体中的典型位置的构象中，但它阻止了RF2保守的和催化必需的GGQ基序在PTC中采用其活性构象。这解释了TNAC肽的翻译如何有效地允许核糖体作为L-Trp特异性的小分子传感器来调节TNACAB操纵子。
In Escherichia coli, elevated levels of free l-tryptophan (l-Trp) promote translational arrest of the TnaC peptide by inhibiting its termination. However, the mechanism by which translation-termination by the UGA-specific decoding release factor 2 (RF2) is inhibited at the UGA stop codon of stalled TnaC-ribosome-nascent chain complexes has so far been ambiguous. This study presents cryo-EM structures for ribosomes stalled by TnaC in the absence and presence of RF2 at average resolutions of 2.9 and 3.5 Å, respectively. Stalled TnaC assumes a distinct conformation composed of two small α-helices that act together with residues in the peptide exit tunnel (PET) to coordinate a single L-Trp molecule. In addition, while the peptidyl-transferase center (PTC) is locked in a conformation that allows RF2 to adopt its canonical position in the ribosome, it prevents the conserved and catalytically essential GGQ motif of RF2 from adopting its active conformation in the PTC. This explains how translation of the TnaC peptide effectively allows the ribosome to function as a L-Trp-specific small-molecule sensor that regulates the tnaCAB operon.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
16.6
作者：
Chan, Kai-Hsin;Petrychenko, Valentyn;Rodnina, Marina V.
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影响因子：
7.7
作者：
Demo, Gabriel;Svidritskiy, Egor;Korostelev, Andrei A.
通讯作者：
Korostelev, Andrei A.
DOI：
10.1107/s0907444909052925
发表时间：
2010-02
期刊：
Acta crystallographica. Section D, Biological crystallography
影响因子：
--
作者：
Adams PD;Afonine PV;Bunkóczi G;Chen VB;Davis IW;Echols N;Headd JJ;Hung LW;Kapral GJ;Grosse-Kunstleve RW;McCoy AJ;Moriarty NW;Oeffner R;Read RJ;Richardson DC;Richardson JS;Terwilliger TC;Zwart PH
通讯作者：
Zwart PH
影响因子：
16
作者：
Cruz-Vera, LR;Rajagopal, S;Yanofsky, C
通讯作者：
Yanofsky, C