Regulation of translation by the Redox State of Elongation factor G in the cyanobacterium Synechocystis sp. PCC 6803

Kouji Kojima, Ken Motohashi, Takuya Morota, Masaru Oshita, Toru Hisabori, Hidenori Hayashi, Yoshitaka Nishiyama

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56 Citations (Scopus)


Elongation factor G (EF-G), a key protein in translational elongation, was identified as a primary target of inactivation by reactive oxygen species within the translational machinery of the cyanobacterium Synechocystis sp. PCC 6803 (Kojima, K., Oshita, M., Nanjo, Y., Kasai, K., Tozawa, Y., Hayashi, H., and Nishiyama, Y. (2007) Mol. Microbiol. 65, 936-947). In the present study, we found that inactivation of EF-G (Slr1463) by H2O2 was attributable to the oxidation of two specific cysteine residues and formation of a disulfide bond. Substitution of these cysteine residues by serine residues protected EF-G from inactivation by H2O2 and allowed the EF-G to mediate translation in a translation system in vitro that had been prepared from Synechocystis. The disulfide bond in oxidized EF-G was reduced by thioredoxin, and the resultant reduced form of EF-G regained the activity to mediate translation in vitro. Western blotting analysis showed that levels of the oxidized form of EF-G increased under strong light in a mutant that lacked NADPH-thioredoxin reductase, indicating that EF-G is reduced by thioredoxin in vivo. These observations suggest that the translational machinery is regulated by the redox state of EF-G, which is oxidized by reactive oxygen species and reduced by thioredoxin, a transmitter of reducing signals generated by the photosynthetic transport of electrons.

Original languageEnglish
Pages (from-to)18685-18691
Number of pages7
JournalJournal of Biological Chemistry
Issue number28
Publication statusPublished - 2009 Jul 10
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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