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首页> 外文期刊>Biochemistry >Interaction of IF2 with the Ribosomal GTPase-Associated Center during 70S Initiation Complex Formation
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Interaction of IF2 with the Ribosomal GTPase-Associated Center during 70S Initiation Complex Formation

机译：在70S起始复合物形成过程中IF2与核糖体GTPase相关中心的相互作用

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摘要

Addition of an Escherichia coli 50S subunit (50SCy5n) containing a Cy5-labeled L11 N-terminalndomain (L11-NTD) within the GTPase-associated center (GAC) to an E. coli 30S initiation complexn(30SICCy3n) containing Cy3-labeled initiation factor 2 complexed with GTP leads to rapid development of anFRET signal during formation of the 70S initiation complex (70SIC). Initiation factor 2 (IF2) and elongationnfactor G (EF-G) induce similar changes in ribosome structure. Here we show that such similarities arenmaintained on a dynamic level as well. Thus, movement of IF2 toward L11-NTD after initial 70S ribosomenformation follows GTP hydrolysis and precedes Pi release, paralleling movement of EF-G following itsnbinding to the ribosome [Seo,H., et al. (2006) Biochemistry 45, 2504-2514], and in both cases, the rate of suchnmovement is slowed if GTP hydrolysis is prevented. The 30SICCy3n:50SCy5nFRET signal also provides ansensitive probe of the ability of initiation factor 3 to discriminate between a canonical and a noncanonicalninitiation codon during 70SIC formation. We employ Bacillus stearothermophilus IF2 as a substitute fornE. coli IF2 to take advantage of the higher stability of the complexes it formswith E. coli ribosomes.While Bst-nIF2 is fully functional in formation of E. coli 70SIC, relative reactivities toward dipeptide formation of 70SICsnformed with the two IF2s suggest that the Bst-IF2 3nGDP complex is more difficult to displace from the GACnthan the E. coli IF2 3nGDP complex.
机译：将GTPase相关中心（GAC）中含有Cy5标记的L11 N-末端域（L11-NTD）的大肠杆菌50S亚基（50SCy5n）添加到含有Cy3标记的起始因子的大肠杆菌30S起始复合物（30SICCy3n） 2与GTP形成复合物会导致70S起始复合物（70SIC）形成过程中anFRET信号的快速发展。起始因子2（IF2）和延伸因子G（EF-G）诱导了核糖体结构的类似变化。在这里，我们表明，这种相似性也保持在动态水平上。因此，在最初的70S核糖体形成后，IF2向L11-NTD的运动跟随GTP水解并在Pi释放之前，与EF-G结合至核糖体后的运动平行[Seo，H.，et al。等。 （2006）Biochemistry 45，2504-2514]，并且在两种情况下，如果防止了GTP水解，这种运动的速度都会减慢。 30SICCy3n：50SCy5nFRET信号还提供了一个敏感的探针，用于探讨在70SIC形成过程中起始因子3区分正则和非正则起始密码子的能力。我们采用嗜热脂肪芽孢杆菌IF2替代nE。大肠杆菌IF2可以利用其与大肠杆菌核糖体形成的复合物的更高稳定性。虽然Bst-nIF2在大肠杆菌70SIC的形成中具有完全功能，但对由两个IF2形成的70SIC的二肽形成的相对反应性表明，Bst-nIF2 IF2 3nGDP复合物比大肠杆菌IF2 3nGDP复合物更难从GACn置换。

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  • 来源
    《Biochemistry》 |2009年第22期|p.4699-4706|共8页
  • 作者

    Haiou Qin Christina Grigoriadou and Barry S. Cooperman;

  • 作者单位

    Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323‡Current address: Department ofMolecular Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080-4918;

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