Topography of human cytochrome b5/cytochrome b5 reductase interacting domain and redox alterations upon complex formation

Biochim Biophys Acta Bioenerg. 2018 Feb;1859(2):78-87. doi: 10.1016/j.bbabio.2017.10.005. Epub 2017 Oct 28.

Abstract

Cytochrome b5 is the main electron acceptor of cytochrome b5 reductase. The interacting domain between both human proteins has been unidentified up to date and very little is known about its redox properties modulation upon complex formation. In this article, we characterized the protein/protein interacting interface by solution NMR and molecular docking. In addition, upon complex formation, we measured an increase of cytochrome b5 reductase flavin autofluorescence that was dependent upon the presence of cytochrome b5. Data analysis of these results allowed us to calculate a dissociation constant value between proteins of 0.5±0.1μM and a 1:1 stoichiometry for the complex formation. In addition, a 30mV negative shift of cytochrome b5 reductase redox potential in presence of cytochrome b5 was also measured. These experiments suggest that the FAD group of cytochrome b5 reductase increase its solvent exposition upon complex formation promoting an efficient electron transfer between the proteins.

Keywords: Autofluorescence; Cytochrome b(5); Cytochrome b(5) reductase; Dissociation constant; Redox potential.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochrome-B(5) Reductase / chemistry*
  • Cytochrome-B(5) Reductase / genetics
  • Cytochrome-B(5) Reductase / metabolism
  • Cytochromes b5 / chemistry*
  • Cytochromes b5 / genetics
  • Cytochromes b5 / metabolism
  • Flavin-Adenine Dinucleotide / chemistry*
  • Flavin-Adenine Dinucleotide / genetics
  • Flavin-Adenine Dinucleotide / metabolism
  • Humans
  • Magnetic Resonance Spectroscopy
  • Molecular Docking Simulation*
  • Oxidation-Reduction
  • Protein Domains

Substances

  • Flavin-Adenine Dinucleotide
  • Cytochromes b5
  • Cytochrome-B(5) Reductase