Asp563 of the horizontal helix of subunit NuoL is involved in proton translocation by the respiratory complex I

► The respiratory complex I contains an unusual, ‘horizontal’ helix on subunit NuoL. ► We mutated residues of the helix to investigate their role in proton translocation. ► The variants D563XL (X=E, N, Q and A) showed a reduced H+/e− stoichiometry. ► D563L is involved in proton transfer to the membr...

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Bibliographic Details
Published in:FEBS letters 2012-03, Vol.586 (6), p.699-704
Main Authors: Steimle, Stefan, Willistein, Max, Hegger, Patricia, Janoschke, Marco, Erhardt, Heiko, Friedrich, Thorsten
Format: Article
Language:English
Subjects:
2-(N-morpholino)-ethanesulfonic acid
9-amino-6-chloro-2-methoxyacridine
ACMA
Amino Acid Sequence
Animals
Aspartic Acid - metabolism
Complex I
Electron Transport
Electron Transport Complex I - chemistry
Electron Transport Complex I - metabolism
Escherichia coli
Escherichia coli - genetics
Escherichia coli - metabolism
Escherichia coli Proteins - chemistry
Escherichia coli Proteins - genetics
Escherichia coli Proteins - metabolism
Humans
MES
Models, Molecular
Molecular Sequence Data
Mutagenesis, Site-Directed
NADH dehydrogenase
NADH Dehydrogenase - chemistry
NADH Dehydrogenase - genetics
NADH Dehydrogenase - metabolism
Protein Structure, Secondary
Proteoliposome
Proton translocation
proton-pumping NADH:ubiquinone oxidoreductase
Protons
Sequence Alignment
transmembranous
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Summary:► The respiratory complex I contains an unusual, ‘horizontal’ helix on subunit NuoL. ► We mutated residues of the helix to investigate their role in proton translocation. ► The variants D563XL (X=E, N, Q and A) showed a reduced H+/e− stoichiometry. ► D563L is involved in proton transfer to the membranous translocation site. The NADH:ubiquinone oxidoreductase couples the electron transfer from NADH to ubiquinone with the translocation of protons across the membrane. It contains a 110Å long helix running parallel to the membrane part of the complex. Deletion of the helix resulted in a reduced H+/e− stoichiometry indicating its direct involvement in proton translocation. Here, we show that the mutation of the conserved amino acid D563L, which is part of the horizontal helix of the Escherichia coli complex I, leads to a reduced H+/e− stoichiometry. It is discussed that this residue is involved in transferring protons to the membranous proton translocation site.
ISSN:0014-5793
1873-3468
DOI:10.1016/j.febslet.2012.01.056