Premium
Evidence for transmembrane proton transfer in a dihaem‐containing membrane protein complex
Author(s) -
Madej M Gregor,
Nasiri Hamid R,
Hilgendorff Nicole S,
Schwalbe Harald,
Lancaster C Roy D
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601361
Subject(s) - biology , transmembrane protein , membrane protein , biophysics , membrane , biochemistry , microbiology and biotechnology , receptor
Membrane protein complexes can support both the generation and utilisation of a transmembrane electrochemical proton potential (‘proton‐motive force’), either by transmembrane electron transfer coupled to protolytic reactions on opposite sides of the membrane or by transmembrane proton transfer. Here we provide the first evidence that both of these mechanisms are combined in the case of a specific respiratory membrane protein complex, the dihaem‐containing quinol:fumarate reductase (QFR) of Wolinella succinogenes , so as to facilitate transmembrane electron transfer by transmembrane proton transfer. We also demonstrate the non‐functionality of this novel transmembrane proton transfer pathway (‘E‐pathway’) in a variant QFR where a key glutamate residue has been replaced. The ‘E‐pathway’, discussed on the basis of the 1.78‐Å‐resolution crystal structure of QFR, can be concluded to be essential also for the viability of pathogenic ε‐proteobacteria such as Helicobacter pylori and is possibly relevant to proton transfer in other dihaem‐containing membrane proteins, performing very different physiological functions.