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Internal switches modulating electron tunneling currents in respiratory complex III.

Muhammad A Hagras1, Alexei A Stuchebrukhov1

  • 1Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, United States.

Biochimica Et Biophysica Acta
|February 14, 2016
PubMed
Summary

Key residues in the bc1 complex adopt different conformations, influencing electron transfer rates and potentially gating the Q-cycle. This study details inter-monomeric electron transfer and communication pathways.

Keywords:
Aromatic–aromatic interactionsElectron tunnelingInternal switchbc1 complex

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Area of Science:

  • Biochemistry
  • Structural Biology
  • Computational Biology

Background:

  • The bc1 complex is crucial for cellular respiration, facilitating electron transfer via quinone (Q)-cycle.
  • X-ray crystallography reveals conformational heterogeneity in key residues of electron tunneling pathways.
  • Understanding these dynamics is vital for elucidating enzyme function and regulation.

Purpose of the Study:

  • To investigate the role of conformational changes in key residues of the bc1 complex.
  • To analyze the impact of these conformations on electron transfer rates.
  • To propose a gating mechanism for the Q-cycle involving inter-monomeric electron transfer.

Main Methods:

  • Analysis of X-ray crystal structures of the bc1 complex.
  • Computational modeling of electron transfer pathways.
  • Examination of inter-monomeric electronic communication.

Main Results:

  • Key residues in electron tunneling pathways exhibit distinct conformations across different crystal structures.
  • Conformational changes significantly modulate electron transfer rates between redox pairs.
  • Aromatic-aromatic interactions play a key role in the protein's communication network.

Conclusions:

  • Conformational flexibility of key residues is critical for regulating electron transfer in the bc1 complex.
  • These conformational dynamics suggest a potential gating function in the Q-cycle.
  • Inter-monomeric electronic communication is an important aspect of bc1 complex function.