Selenite assimilation into formate dehydrogenase H depends on thioredoxin reductase in Escherichia coli

Muneaki Takahata, Takashi Tamura, Katsumasa Abe, Hisaaki Mihara, Suguru Kurokawa, Yoshihiro Yamamoto, Ryuhei Nakano, Nobuyoshi Esaki, Kenji Inagaki

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Escherichia coli growing under anaerobic conditions produce H2 and CO2 by the enzymatic cleavage of formate that is produced from pyruvate at the end of glycolysis. Selenium is an integral part of formate dehydrogenase H (FDHH), which catalyses the first step in the formate hydrogen lyase (FHL) system. The genes of FHL system are transcribed only under anaerobic conditions, in the presence of a σ54-dependent transcriptional activator FhlA that binds formate as an effector molecule. Although the formate addition to the nutrient media has been an established procedure for inducing high FDHH activity, we have identified a low-salt nutrient medium containing <0.1% NaCl enabled constitutive, high expression of FDHH even without formate and d-glucose added to the medium. The novel conditions allowed us to study the effects of disrupting genes like trxB (thioredoxin reductase) or gor (glutathione reductase) on the production of FDHH activity and also reductive assimilation of selenite (SeO3 2-) into the selenoprotein. Despite the widely accepted hypothesis that selenite is reduced by glutathione reductase-dependent system, it was demonstrated that trxB gene was essential for FDHH production and for labelling the FDHH polypeptide with 75Se-selenite. Our present study reports for the first time the physiological involvement of thioredoxin reductase in the reductive assimilation of selenite in E. coli.

Original languageEnglish
Pages (from-to)467-473
Number of pages7
JournalJournal of biochemistry
Volume143
Issue number4
DOIs
Publication statusPublished - Apr 2008

Keywords

  • Formate dehydrogenase H
  • Selenite assimilation
  • Thioredoxin reductase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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