Reorganization and conformational changes in the reduction of tetraheme cytochromes

A Sofia F Oliveira, Vitor H Teixeira, António M Baptista, Cláudio M Soares

Research output: Contribution to journalArticle (Academic Journal)peer-review

20 Citations (Scopus)

Abstract

Molecular dynamics simulation (MD) constitutes an alternative to time-consuming experiments for studying conformational changes. We apply MD on a redox system where experimental information exists for the fully oxidized and fully reduced states: tetraheme cytochrome c3. Instead of doing one simulation for each state, we apply 10 4-ns replicas for both states, which provides robust statistics to characterize the redox changes. Besides these long simulations, we perform 120 short ones (50 ps), where an equilibrated oxidized state is perturbed to a reduced state. This allows the application of a nonequilibrium method, the subtraction technique, which makes it possible to characterize the different timescales of conformational changes. Reduction induces conformational changes in the N-terminus and on the loops spanning residues 36-42 and 88-93, which correlate very well with experiments, demonstrating the applicability of this methodology. We also analyze the effect of reduction on hydrogen bonds, solvent accessible surface and bound water, the changes being found to involve the hemes and propionate groups. Redox-induced protonation is also investigated, by protonating the propionates D from hemes I and IV. Although this change in the former does not have major conformational consequences, it induces in the latter conformational changes beyond the ones obtained with reduction.

Original languageEnglish
Pages (from-to)3919-30
Number of pages12
JournalBiophysical Journal
Volume89
Issue number6
DOIs
Publication statusPublished - Dec 2005

Keywords

  • Computer Simulation
  • Cytochrome c Group
  • Heme
  • Hydrogen Bonding
  • Kinetics
  • Models, Chemical
  • Models, Molecular
  • Oxidation-Reduction
  • Protein Conformation
  • Solvents
  • Journal Article
  • Research Support, Non-U.S. Gov't

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