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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 Krueger
  • 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
Journal number12
Volume193
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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