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Structural differences of oxidized iron-sulfur and nickel-iron cofactors in O2-tolerant and O2-sensitive hydrogenases studied by X-ray absorption spectroscopy

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Published copy (DOI)

Author(s)

  • Kajsa G V Sigfridsson
  • Nils Leidel
  • Oliver Sanganas
  • Petko Chernev
  • Oliver Lenz
  • Ki-Seok Yoon
  • Hirofumi Nishihara
  • Alison Parkin
  • Fraser A Armstrong
  • Sébastien Dementin
  • Marc Rousset
  • Antonio L De Lacey
  • Michael Haumann

Department/unit(s)

Publication details

JournalBiochimica et biophysica acta
DatePublished - Feb 2015
Issue number2
Volume1847
Number of pages9
Pages (from-to)162-70
Original languageEnglish

Abstract

The class of [NiFe]-hydrogenases comprises oxygen-sensitive periplasmic (PH) and oxygen-tolerant membrane-bound (MBH) enzymes. For three PHs and four MBHs from six bacterial species, structural features of the nickel-iron active site of hydrogen turnover and of the iron-sulfur clusters functioning in electron transfer were determined using X-ray absorption spectroscopy (XAS). Fe-XAS indicated surplus oxidized iron and a lower number of ~2.7 Å Fe-Fe distances plus additional shorter and longer distances in the oxidized MBHs compared to the oxidized PHs. This supported a double-oxidized and modified proximal FeS cluster in all MBHs with an apparent trimer-plus-monomer arrangement of its four iron atoms, in agreement with crystal data showing a [4Fe3S] cluster instead of a [4Fe4S] cubane as in the PHs. Ni-XAS indicated coordination of the nickel by the thiol group sulfurs of four conserved cysteines and at least one iron-oxygen bond in both MBH and PH proteins. Structural differences of the oxidized inactive [NiFe] cofactor of MBHs in the Ni-B state compared to PHs in the Ni-A state included a ~0.05 Å longer Ni-O bond, a two times larger spread of the Ni-S bond lengths, and a ~0.1 Å shorter Ni-Fe distance. The modified proximal [4Fe3S] cluster, weaker binding of the Ni-Fe bridging oxygen species, and an altered localization of reduced oxygen species at the active site may each contribute to O2 tolerance.

Bibliographical note

Copyright © 2014 Elsevier B.V. All rights reserved.

    Research areas

  • Binding Sites, Hydrogenase, Iron-Sulfur Proteins, Oxidation-Reduction, Oxygen, X-Ray Absorption Spectroscopy

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