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Research article - Peer-reviewed, 2009

Structures of the multicomponent Rieske non-heme iron toluene 2,3-dioxygenase enzyme system

Friemann, Rosmarie; Lee, Kyoung; Brown, Eric N.; Gibson, David T; Eklund, Hans; Ramaswamy, S

Abstract

Bacterial Rieske non-heme iron oxygenases catalyze the initial hydroxylation of aromatic hydrocarbon substrates. The structures of all three components of one such system, the toluene 2,3-dioxygenase system, have now been determined. This system consists of a reductase, a ferredoxin and a terminal dioxygenase. The dioxygenase, which was cocrystallized with toluene, is a heterohexamer containing a catalytic and a structural subunit. The catalytic subunit contains a Rieske [2Fe-2S] cluster and mononuclear iron at the active site. This iron is not strongly bound and is easily removed during enzyme purification. The structures of the enzyme with and without mononuclear iron demonstrate that part of the structure is flexible in the absence of iron. The orientation of the toluene substrate in the active site is consistent with the regiospecificity of oxygen incorporation seen in the product formed. The ferredoxin is Rieske type and contains a [2Fe-2S] cluster close to the protein surface. The reductase belongs to the glutathione reductase family of flavoenzymes and consists of three domains: an FAD-binding domain, an NADH-binding domain and a C-terminal domain. A model for electron transfer from NADH via FAD in the reductase and the ferredoxin to the terminal active-site mononuclear iron of the dioxygenase is proposed.

Published in

Acta Crystallographica Section D: Biological Crystallography
2009, Volume: 65, pages: 24-33
Publisher: WILEY-BLACKWELL PUBLISHING, INC

      SLU Authors

    • Friemann, Rosmarie

      • Department of Molecular Biology, Swedish University of Agricultural Sciences
      • Eklund, Hans

        • Department of Molecular Biology, Swedish University of Agricultural Sciences

      UKÄ Subject classification

      Biochemistry and Molecular Biology
      Biophysics

      Publication identifier

      DOI: https://doi.org/10.1107/S0907444908036524

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/44561