title: Elongation factor G is a critical target during oxidative damage to the translation system of Escherichia coli.
abstract: Elongation factor G (EF-G), a key protein in translational elongation, is known to be particularly susceptible to oxidation in Escherichia coli. However, neither the mechanism of the oxidation of EF-G nor the influence of its oxidation on translation is fully understood. In the present study, we investigated the effects of oxidants on the chemical properties and function of EF-G using a translation system in vitro derived from E. coli. Treatment of EF-G with 0.5 mM H(2)O(2) resulted in the complete loss of translational activity. The inactivation of EF-G by H(2)O(2) was attributable to the oxidation of two specific cysteine residues, namely, Cys(114) and Cys(266), and subsequent formation of an intramolecular disulfide bond. Replacement of Cys(114) by serine rendered EF-G insensitive to oxidation and inactivation by H(2)O(2). Furthermore, generation of the translation system in vitro with the mutated EF-G protected the entire translation system from oxidation, suggesting that EF-G might be a primary target of oxidation within the translation system. Oxidized EF-G was reactivated via reduction of the disulfide bond by thioredoxin, a ubiquitous protein that mediates dithiol-disulfide exchange. Our observations indicate that the translational machinery in E. coli is regulated, in part, by the redox state of EF-G, which might depend on the balance between the supply of reducing power and the degree of oxidative stress.
authors: Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
authors: Takanori
authors: T
authors: Nagano
authors: Kouji
authors: K
authors: Kojima
authors: Toru
authors: T
authors: Hisabori
authors: Hidenori
authors: H
authors: Hayashi
authors: Eugene Hayato
authors: EH
authors: Morita
authors: Takashi
authors: T
authors: Kanamori
authors: Tomoko
authors: T
authors: Miyagi
authors: Takuya
authors: T
authors: Ueda
authors: Yoshitaka
authors: Y
authors: Nishiyama
mesh_terms: D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D020653:Peptide Elongation Factor G / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000502:physiology*
chemical_list: D004220:Disulfides; D029968:Escherichia coli Proteins; D016877:Oxidants; D020653:Peptide Elongation Factor G; D006861:Hydrogen Peroxide; D003545:Cysteine