Extremophiles

, Volume 14, Issue 1, pp 79–85

Carboxylation reaction catalyzed by 2-oxoglutarate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus

  • Masahiro Yamamoto
  • Takeshi Ikeda
  • Hiroyuki Arai
  • Masaharu Ishii
  • Yasuo Igarashi
Original Paper

DOI: 10.1007/s00792-009-0289-4

Cite this article as:
Yamamoto, M., Ikeda, T., Arai, H. et al. Extremophiles (2010) 14: 79. doi:10.1007/s00792-009-0289-4

Abstract

Hydrogenobacter thermophilus TK-6 is a thermophilic, chemolithoautotrophic, hydrogen-oxidizing bacterium that fixes carbon dioxide via the reductive tricarboxylic acid (rTCA) cycle. 2-Oxoglutarate:ferredoxin oxidoreductase (OGOR) is the key enzyme in this cycle that fixes carbon dioxide. The genome of strain TK-6 encodes at least two distinct OGOR enzymes, termed For and Kor. We report here a method for measuring the carboxylation of succinyl-CoA catalyzed by OGORs. The method involves the in vitro coupling of OGOR with ferredoxin and pyruvate:ferredoxin oxidoreductase from strain TK-6, and glutamate dehydrogenase from Sulfolobus tokodaii. Using this method, we determined both the apparent maximum velocities and the Km values of For and Kor for the carboxylation of succinyl-CoA. This is the first reported kinetic analysis of carbon fixation catalyzed by OGOR enzymes from the rTCA cycle.

Keywords

Hydrogenobacter thermophilus2-Oxoglutarate:ferredoxin oxidoreductaseReductive tricarboxylic acid cycleCarboxylationPyruvate:ferredoxin oxidoreductase

Abbreviations

rTCA

Reductive tricarboxylic acid

OGOR

2-Oxoglutarate:ferredoxin oxidoreductase

OR

2-Oxoacid oxidoreductase

POR

Pyruvate:ferredoxin oxidoreductase

GDH

Glutamate dehydrogenase

Copyright information

© Springer 2009

Authors and Affiliations

  • Masahiro Yamamoto
    • 1
  • Takeshi Ikeda
    • 1
  • Hiroyuki Arai
    • 1
  • Masaharu Ishii
    • 1
  • Yasuo Igarashi
    • 1
  1. 1.Department of BiotechnologyUniversity of TokyoTokyoJapan