Oxidation of translation factor EF-G transiently retards the translational elongation cycle in Escherichia coli
Oxidation of translation factor EF-G transiently retards the translational elongation cycle in Escherichia coli
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翻译因子 EF-G 的氧化短暂延迟了大肠杆菌的翻译延伸周期
DOI：
10.1093/jb/mvv026
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Y.
中科院分区：
文献类型：
--
作者：
Nagano;T.;Yutthanasirikul;R.;Hihara;Y.;Hisabori;T.;Kanamori;T.;Takeuchi;N.;Ueda;T. and Nishiyama;Y.
在大肠杆菌中，延伸因子G（EF-G）是翻译延伸的关键蛋白，对氧化特别敏感。我们以前证明，EF-G是失活后形成的分子内二硫键。然而，EF-G的氧化抑制EF-G在核糖体上的功能的机制的细节仍有待阐明。用过氧化氢氧化EF-G后，EF-G插入核糖体的能力和体外单循环转运活性均未受到影响。但EF-G被氧化后，GT3活性和EF-G从核糖体上的解离受到抑制。当EF-G被氧化时，较长肽的合成比较短肽的合成受到更大程度的抑制。因此，EF-G中二硫键的形成可能会干扰GTP的水解，而GTP的水解与EF-G从核糖体的解离偶联，从而可能会延迟EF-G在翻译机器内的周转。当我们将硫氧还蛋白添加到包括氧化EF-G的受抑制的翻译系统中时，翻译活性几乎立即恢复。我们认为，EF-G的氧化可能提供了一个短暂的和可逆的抑制翻译inE的调节机制。大肠杆菌在氧化胁迫下的生长。
InEscherichia coli,elongation factor G (EF-G), a key protein in translational elongation, is particularly susceptible to oxidation. We demonstrated previously that EF-G is inactivated upon formation of an intramolecular disulphide bond. However, the details of the mechanism by which the oxidation of EF-G inhibits the function of EF-G on the ribosome remain to be elucidated. When we oxidized EF-G with hydrogen peroxide, neither the insertion of EF-G into the ribosome nor single-cycle translocation activityin vitrowas affected. However, the GTPase activity and the dissociation of EF-G from the ribosome were suppressed when EF-G was oxidized. The synthesis of longer peptides was suppressed to a greater extent than that of a shorter peptide when EF-G was oxidized. Thus, the formation of the disulphide bond in EF-G might interfere with the hydrolysis of GTP that is coupled with dissociation of EF-G from the ribosome and might thereby retard the turnover of EF-G within the translational machinery. When we added thioredoxin to the suppressed translation system that included oxidized EF-G, translational activity was almost immediately restored. We propose that oxidation of EF-G might provide a regulatory mechanism for transient and reversible suppression of translation inE. coliunder oxidative stress.