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Efficient electron transfer from hydrogen to benzyl viologen by the [NiFe]-hydrogenases of Escherichia coli is dependent on the coexpression of the iron-sulfur cluster-containing small subunit

Efficient electron transfer from hydrogen to benzyl viologen by the [NiFe]-hydrogenases of Escherichia coli is dependent on the coexpression of the iron-sulfur cluster-containing small subunit

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Authors

  • Constanze Pinske
  • Sara Krüger
  • Basem Soboh
  • Christian Ihling
  • Martin Kuhns
  • Mario Braussemann
  • Monique Jaroschinsky
  • Christopher Sauer
  • Frank Sargent
  • Andrea Sinz
  • R. Gary Sawers

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Original languageEnglish
Pages893-903
Number of pages11
JournalArchives of Microbiology
Journal publication dateDec 2011
Volume193
Issue12
DOIs
StatePublished

Abstract

Escherichia coli can both oxidize hydrogen and reduce protons. These activities involve three distinct [NiFe]-hydrogenases, termed Hyd-1, Hyd-2, and Hyd-3, each minimally comprising heterodimers of a large subunit, containing the [NiFe] active site, and a small subunit, bearing iron-sulfur clusters. Dihydrogen-oxidizing activity can be determined using redox dyes like benzyl viologen (BV); however, it is unclear whether electron transfer to BV occurs directly at the active site, or via an iron-sulfur center in the small subunit. Plasmids encoding Strep-tagged derivatives of the large subunits of the three E. coli [NiFe]-hydrogenases restored activity of the respective hydrogenase to strain FTD147, which carries in-frame deletions in the hyaB, hybC, and hycE genes encoding the large subunits of Hyd-1, Hyd-2, and Hyd-3, respectively. Purified Strep-HyaB was associated with the Hyd-1 small subunit (HyaA), and purified Strep-HybC was associated with the Hyd-2 small subunit (HybO), and a second iron-sulfur protein, HybA. However, Strep-HybC isolated from a hybO mutant had no other associated subunits and lacked BV-dependent hydrogenase activity. Mutants deleted separately for hyaA, hybO, or hycG (Hyd-3 small subunit) lacked BV-linked hydrogenase activity, despite the Hyd-1 and Hyd-2 large subunits being processed. These findings demonstrate that hydrogenase-dependent reduction of BV requires the small subunit.

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