The roles of initiation factor 2 and guanosine triphosphate in initiation of protein synthesis
The roles of initiation factor 2 and guanosine triphosphate in initiation of protein synthesis
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DOI：
10.1093/emboj/cdg525
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发表时间：
2003-10-15
期刊：
影响因子：
11.4
通讯作者：
Ehrenberg, M
中科院分区：
文献类型：
--
作者：
Antoun, A;Pavlov, MY;Ehrenberg, M
IF 2从大肠杆菌的作用进行了研究，在体外使用纯化的组分与蛋白质合成系统。光散射的停流实验表明，IF 2与三磷酸鸟苷（GTP）或不可裂解的GTP类似物（GDPNP）复合，但不与二磷酸鸟苷（GDP）复合，在起始过程中促进核糖体亚基的快速结合。生物化学实验表明，IF 2促进快速形成的第一个肽键在GTP的存在下，但不是GDPNP或GDP，IF 2-GDPNP强烈结合后起始核糖体。我们得出结论，GTP形式的IF 2加速形成的70 S核糖体从亚基和GTP水解加速IF 2从70 S核糖体的释放。最近的一份报告的结果表明，GTP和GDP促进启动同样快，已经解决。我们的数据，表明eIF 5 B和IF 2具有相似的功能，用于合理化的GTP酶缺陷突变体的eIF 5 B和IF 2的表型。
The role of IF2 from Escherichia coli was studied in vitro using a system for protein synthesis with purified components. Stopped flow experiments with light scattering show that IF2 in complex with guanosine triphosphate (GTP) or a non-cleavable GTP analogue (GDPNP), but not with guanosine diphosphate (GDP), promotes fast association of ribosomal subunits during initiation. Biochemical experiments show that IF2 promotes fast formation of the first peptide bond in the presence of GTP, but not GDPNP or GDP, and that IF2-GDPNP binds strongly to post-initiation ribosomes. We conclude that the GTP form of IF2 accelerates formation of the 70S ribosome from subunits and that GTP hydrolysis accelerates release of IF2 from the 70S ribosome. The results of a recent report, suggesting that GTP and GDP promote initiation equally fast, have been addressed. Our data, indicating that eIF5B and IF2 have similar functions, are used to rationalize the phenotypes of GTPase-deficient mutants of eIF5B and IF2.