Biochemical and molecular characterization of the [NiFe] hydrogenase from the hyperthermophilic archaeon, Thermococcus litoralis

Gábor Rákhely, Zhi H. Zhou, Michael W.W. Adams, Kornél L. Kovács

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23 Citations (Scopus)

Abstract

Thermococcus litoralis is a hyperthermophilic archaeon that grows at temperatures up to 98 °C by fermentative metabolism and reduces elemental sulfur (S°) to H2S. A [NiFe] hydrogenase, responsible for H2S or H2 production, has been purified and characterized. The enzyme is composed of four subunits with molecular mass 46, 42, 34 and 32 kDa. Elemental analyses gave approximate values of 22 Fe, 22 S and 1 Ni per hydrogenase. EPR spectra at 70 and 5 K indicated the presence of four or five [4Fe-4S] and one [2Fe- 2S] type clusters. The optimal temperature for both H2 evolution and oxidation, using artificial electron carriers, was around 80 °C. The operon encoding the T. litoralis enzyme is composed of four genes forming one transcriptional unit, and transcription is not regulated by S°. An unusual transcription-initiation site is located 139 bp upstream from the translational start point. Sequence analyses indicated the presence of new putative nucleotide-binding domains. Upstream from the hydrogenase operon, ORFs probably encoding a molybdopterin oxidoreductase enzyme have been identified. Based on sequence, biochemical and biophysical analyses, a model of the enzyme and the pathway of electron flow during catalysis is proposed.

Original languageEnglish
Pages (from-to)1158-1165
Number of pages8
JournalEuropean Journal of Biochemistry
Volume266
Issue number3
DOIs
Publication statusPublished - Dec 15 1999

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Keywords

  • Hydrogen evolution
  • Hyperthermophilic
  • Nucleotide- binding domains
  • Thermo-coccus litoralis
  • [NiFe] hydrogenase

ASJC Scopus subject areas

  • Biochemistry

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