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  The structure of Aquifex aeolicus sulfide:quinone oxidoreductase, a basis to understand sulfide detoxification and respiration

Marcia, M., Ermler, U., Peng, G., & Michel, H. (2009). The structure of Aquifex aeolicus sulfide:quinone oxidoreductase, a basis to understand sulfide detoxification and respiration. Proceedings of the National Academy of Sciences of the United States of America, 106(24), 9625-9630. doi:10.1073/pnas.0904165106.

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 Creators:
Marcia, Marco1, Author           
Ermler, Ulrich1, Author           
Peng, Guohong1, 2, Author           
Michel, Hartmut1, Author           
Affiliations:
1Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068290              
2Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China, ou_persistent22              

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Free keywords: Flavoprotein; monotopic membrane protein; sulfide metabolism; X-ray crystallography; extremophilic organism
 Abstract: Sulfide:quinone oxidoreductase (SQR) is a flavoprotein with homologues in all domains of life except plants. It plays a physiological role both in sulfide detoxification and in energy transduction. We isolated the protein from native membranes of the hyperthermophilic bacterium Aquifex aeolicus, and we determined its X-ray structure in the ‘‘as-purified,’’ substrate-bound, and inhibitorbound forms at resolutions of 2.3, 2.0, and 2.9 Å, respectively. The structure is composed of 2 Rossmann domains and 1 attachment domain, with an overall monomeric architecture typical of disulfide oxidoreductase flavoproteins. A. aeolicus SQR is a surprisingly trimeric, periplasmic integral monotopic membrane protein that inserts about 12 Å into the lipidic bilayer through an amphipathic helix–turn–helix tripodal motif. The quinone is located in a channel that extends from the si side of the FAD to the membrane. The quinone ring is sandwiched between the conserved amino acids Phe-385 and Ile-346, and it is possibly protonated upon reduction via Glu-318 and/or neighboring water molecules. Sulfide polymerization occurs on the re side of FAD, where the invariant Cys-156 and Cys-347 appear to be covalently bound to polysulfur fragments. The structure suggests that FAD is covalently linked to the polypeptide in an unusual way, via a disulfide bridge between the 8-methyl group and Cys-124. The applicability of this disulfide bridge for transferring electrons from sulfide to FAD, 2 mechanisms for sulfide polymerization and channeling of the substrate, S2-, and of the product, Sn, in and out of the active site are discussed

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Language(s): eng - English
 Dates: 2009-02-272009-06-012009-06-16
 Publication Status: Published in print
 Pages: 6
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1073/pnas.0904165106
 Degree: -

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Title: Proceedings of the National Academy of Sciences of the United States of America
  Other : Proc. Acad. Sci. USA
  Other : Proc. Acad. Sci. U.S.A.
  Other : Proceedings of the National Academy of Sciences of the USA
  Abbreviation : PNAS
Source Genre: Journal
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Publ. Info: Washington, D.C. : National Academy of Sciences
Pages: - Volume / Issue: 106 (24) Sequence Number: - Start / End Page: 9625 - 9630 Identifier: ISSN: 0027-8424
CoNE: https://pure.mpg.de/cone/journals/resource/954925427230