Redox-dependent conformational changes in eukaryotic cytochromes revealed by paramagnetic NMR spectroscopy.

TitleRedox-dependent conformational changes in eukaryotic cytochromes revealed by paramagnetic NMR spectroscopy.
Publication TypeJournal Article
Year of Publication2012
AuthorsVolkov, A., S. Vanwetswinkel, K. Van de Water, and N. A. J. van Nuland
JournalJ Biomol NMR
Volume52
Issue3
Pagination245-56
Date Published2012 Mar
ISSN1573-5001
KeywordsCytochromes, Magnetic Resonance Spectroscopy, Oxidation-Reduction, Protein Conformation
Abstract

Cytochrome c (Cc) is a soluble electron carrier protein, transferring reducing equivalents between Cc reductase and Cc oxidase in eukaryotes. In this work, we assessed the structural differences between reduced and oxidized Cc in solution by paramagnetic NMR spectroscopy. First, we have obtained nearly-complete backbone NMR resonance assignments for iso-1-yeast Cc and horse Cc in both oxidation states. These were further used to derive pseudocontact shifts (PCSs) arising from the paramagnetic haem group. Then, an extensive dataset comprising over 450 measured PCSs and high-resolution X-ray and solution NMR structures of both proteins were used to define the anisotropic magnetic susceptibility tensor, Δχ. For most nuclei, the PCSs back-calculated from the Δχ tensor are in excellent agreement with the experimental PCS values. However, several contiguous stretches-clustered around G41, N52, and A81-exhibit large deviations both in yeast and horse Cc. This behaviour is indicative of redox-dependent structural changes, the extent of which is likely conserved in the protein family. We propose that the observed discrepancies arise from the changes in protein dynamics and discuss possible functional implications.

DOI10.1007/s10858-012-9607-8
Alternate JournalJ. Biomol. NMR
PubMed ID22318343