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          Institute: MPI für Biophysik     Collection: Abt. Molekulare Membranbiologie     Display Documents

ID: 631612.0, MPI für Biophysik / Abt. Molekulare Membranbiologie
Hydrogen-Bonded Networks Along and Bifurcation of the E-Pathway in Quinol:Fumarate Reductase
Authors:Herzog, Elena; Gu, Wei; Juhnke, Hanno D.; Haas, Alexander H.; Mäntele, Werner; Simon, Jörg; Helms, Volkhard; Lancaster, C. Roy D.
Date of Publication (YYYY-MM-DD):2012-09-19
Title of Journal:Biophysical Journal
Journal Abbrev.:Biophys. J.
Issue / Number:6
Start Page:1305
End Page:1314
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The E-pathway of transmembrane proton transfer has been demonstrated previously to be essential for catalysis by the diheme-containing quinol:fumarate reductase (QFR) of Wolinella succinogenes. Two constituents of this pathway, Glu- C180 and heme bD ring C (bD-C-) propionate, have been validated experimentally. Here, we identify further constituents of the E-pathway by analysis of molecular dynamics simulations. The redox state of heme groups has a crucial effect on the connectivity patterns of mobile internal water molecules that can transiently support proton transfer from the bD-C-propionate to Glu-C180. The short H-bonding paths formed in the reduced states can lead to high proton conduction rates and thus provide a plausible explanation for the required opening of the E-pathway in reduced QFR. We found evidence that the bD-C-propionate group is the previously postulated branching point connecting proton transfer to the E-pathway from the quinol-oxidation site via interactions with the heme bD ligand His-C44. An essential functional role of His-C44 is supported experimentally by site-directed mutagenesis resulting in its replacement with Glu. Although the H44E variant enzyme retains both heme groups, it is unable to catalyze quinol oxidation. All results obtained are relevant to the QFR enzymes from the human pathogens Campylobacter jejuni and Helicobacter pylori.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Biophysik/Abteilung Molekulare Membranbiologie
External Affiliations:Department of Structural Biology, Center of Human and Molecular Biology, Institute of Biophysics, Faculty of Medicine, Saarland University, Homburg, Germany;
Center for Bioinformatics and Center of Human and Molecular Biology, Saarland University, Saarbrücken, Germany;
Institute of Biophysics, Goethe University, Frankfurt am Main, Germany;
Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
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