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ID 34240
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Author
Takahata, Muneaki
Abe, Katsumasa
Mihara, Hisaaki
Kurokawa, Suguru
Yamamoto, Yoshihiro
Nakano, Ryuhei
Esaki, Nobuyoshi
Abstract

Escherichia coli growing under anaerobic conditions produce H-2 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 sigma(54)-dependent transcriptional activator Fh1A 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 (SeO32-) 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 Se-75-selenite. Our present study reports for the first time the physiological involvement of thioredoxin reductase in the reductive assimilation of selenite in E. coli.

Keywords
formate dehydrogenase H
selenite assimilation
thioredoxin reductase
Note
Published with permission from the copyright holder.
This is a author's copy,as published in Journal of Biochemistry , 2008 Vol.143 Issue.4 pp.467-473
Publisher URL: http://dx.doi.org/10.1093/jb/mvm247
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Copyright © 2008 by The Japanese Biochemical Society
Published Date
2008-06-26
Publication Title
Journal of Biochemistry
Volume
volume143
Issue
issue4
Start Page
467
End Page
473
Content Type
Journal Article
language
英語
Refereed
True
DOI
Web of Sience KeyUT
Submission Path
biochemistry/9