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

Steimle, Stefan; Willistein, Max; Hegger, Patricia; Janoschke, Marco; Erhardt, Heiko; Friedrich, Thorsten

doi:10.1016/j.febslet.2012.01.056

Cited by 24 publications

(30 citation statements)

References 42 publications

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“…Although site-directed mutagenesis data (35) suggest that the HL helix might provide a clamping function in complex I rather than the earlier suggested piston function (12), the mutation of this aspartate to a glutamate strongly decreases the proton-pumping activity by approximately 50% (49).…”

Section: Resultsmentioning

confidence: 80%

Symmetry-related proton transfer pathways in respiratory complex I

Luca

Gámiz‐Hernández

Kaila

2017

Proc. Natl. Acad. Sci. U.S.A.

170

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Complex I functions as the initial electron acceptor in aerobic respiratory chains of most organisms. This gigantic redox-driven enzyme employs the energy from quinone reduction to pump protons across its complete approximately 200-Å membrane domain, thermodynamically driving synthesis of ATP. Despite recently resolved structures from several species, the molecular mechanism by which complex I catalyzes this long-range protoncoupled electron transfer process, however, still remains unclear. We perform here large-scale classical and quantum molecular simulations to study the function of the proton pump in complex I from Thermus thermophilus. The simulations suggest that proton channels are established at symmetry-related locations in four subunits of the membrane domain. The channels open up by formation of quasi one-dimensional water chains that are sensitive to the protonation states of buried residues at structurally conserved broken helix elements. Our combined data provide mechanistic insight into long-range coupling effects and predictions for sitedirected mutagenesis experiments.NADH:ubiquinone oxidoreductase | proton pumping | Grotthuss mechanism | multiscale simulation | bioenergetics C omplex I (NADH:ubiquinone reductase) is the largest enzyme of the respiratory chain, generating a proton motive force (pmf) that is used for synthesis of adenosine triphosphate (ATP) and active transport (1, 2). Complex I catalyzes electron transfer (eT) between nicotine adenine dinucleotide (NADH) and quinone (Q), and couples the energy released to pumping of four protons across the membrane (3-9). The distance between the electron and proton transferring modules extends up to approximately 200 Å. It currently remains unclear, however, how complex I catalyzes this remarkable long-range proton-coupled electron transfer (PCET) process. In addition to its central role in biological energy conversion, elucidating the molecular mechanism of complex

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Section: Resultsmentioning

confidence: 80%

Symmetry-related proton transfer pathways in respiratory complex I

Luca

Gámiz‐Hernández

Kaila

2017

Proc. Natl. Acad. Sci. U.S.A.

170

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“…Several previous papers (37)(38)(39)(40) have analyzed the role of the lateral helix through mutagenesis, including amino acid substitutions, insertions, deletions, and truncations of the C-terminal region of subunit L. C-terminal truncations of TM16 and of most of the lateral helix expressed from the chromosome were found by two groups to result in a nearly total loss of activity (37,38). Attempts to purify the truncated enzyme were unsuccessful, as it appeared to be unstable.…”

Section: Discussionmentioning

confidence: 99%

Constraining the Lateral Helix of Respiratory Complex I by Cross-linking Does Not Impair Enzyme Activity or Proton Translocation

Zhu

Vik

2015

Journal of Biological Chemistry

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Background: A lateral helix in the membrane arm of Complex I was proposed to function as a piston during proton translocation. Results: Cross-linking the lateral helix to other subunits did not impair proton translocation. Conclusion: The evidence does not support a piston-type role for the lateral helix. Significance: Energy transduction by Complex I must involve communication through other structural features.

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“…Subunit L differs from the related subunits M and N in that it has 2 additional TM (transmembrane) helices, which are connected by a long lateral helix that contacts subunits M, N and K (Efremov and Sazanov 2011). The role of the lateral helix has been tested by mutagenesis in several recent studies (Belevich et al 2011; Steimle et al 2011; Steimle et al 2015; Steimle et al 2012; Torres-Bacete et al 2011). Proton translocation likely occurs through four pathways.…”

Section: Introductionmentioning

confidence: 99%

Loss of Complex I activity in the Escherichia coli enzyme results from truncating the C-terminus of subunit K, but not from cross-linking it to subunits N or L

Zhu

Canales

Bedair

et al. 2016

J Bioenerg Biomembr

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Complex I is a multi-subunit enzyme of the respiratory chain with seven core subunits in its membrane arm (A, H, J, K, L, M, and N). In the enzyme from Escherichia coli the C-terminal ten amino acids of subunit K lie along the lateral helix of subunit L, and contribute to a junction of subunits K, L and N on the cytoplasmic surface. Using double cysteine mutagenesis, the cross-linking of subunit K (R99C) to either subunit L (K581C) or subunit N (T292C) was attempted. A partial yield of cross-linked product had no effect on the activity of the enzyme, or on proton translocation, suggesting that the C-terminus of subunit K has no dynamic role in function. To further elucidate the role of subunit K genetic deletions were constructed at the C-terminus. Upon the serial deletion of the last 4 residues of the C-terminus of subunit K, various results were obtained. Deletion of one amino acid had little effect on the activity of Complex I, but deletions of 2 or more amino acids led to total loss of enzyme activity and diminished levels of subunits L, M, and N in preparations of membrane vesicles. Together these results suggest that while the C-terminus of subunit K has no dynamic role in energy transduction by Complex I, it is vital for the correct assembly of the enzyme.

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

Cited by 24 publications

References 42 publications

Symmetry-related proton transfer pathways in respiratory complex I

Symmetry-related proton transfer pathways in respiratory complex I

Constraining the Lateral Helix of Respiratory Complex I by Cross-linking Does Not Impair Enzyme Activity or Proton Translocation

Loss of Complex I activity in the Escherichia coli enzyme results from truncating the C-terminus of subunit K, but not from cross-linking it to subunits N or L

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