Redox-induced structural changes in the di-iron and di-manganese forms of Bacillus anthracis ribonucleotide reductase subunit NrdF suggest a mechanism for gating of radical access

Research output: Contribution to journalArticle

Abstract

Class Ib ribonucleotide reductases (RNR) utilize a di-nuclear manganese or iron cofactor for reduction of superoxide or molecular oxygen, respectively. This generates a stable tyrosyl radical (Y·) in the R2 subunit (NrdF), which is further used for ribonucleotide reduction in the R1 subunit of RNR. Here, we report high-resolution crystal structures of Bacillus anthracis NrdF in the metal-free form (1.51 Å) and in complex with manganese (MnII/MnII, 1.30 Å). We also report three structures of the protein in complex with iron, either prepared anaerobically (FeII/FeII form, 1.32 Å), or prepared aerobically in the photo-reduced FeII/FeII form (1.63 Å) and with the partially oxidized metallo-cofactor (1.46 Å). The structures reveal significant conformational dynamics, likely to be associated with the generation, stabilization, and transfer of the radical to the R1 subunit. Based on observed redox-dependent structural changes, we propose that the passage for the superoxide, linking the FMN cofactor of NrdI and the metal site in NrdF, is closed upon metal oxidation, blocking access to the metal and radical sites. In addition, we describe the structural mechanics likely to be involved in this process.

Details

Authors
  • Kristīne Grāve
  • Wietske Lambert
  • Gustav Berggren
  • Julia J. Griese
  • Matthew D. Bennett
  • Derek T. Logan
  • Martin Högbom
Organisations
External organisations
  • Stockholm University
  • Uppsala University
  • PRA Health Sciences, Netherlands
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Structural Biology

Keywords

  • Carboxylate shift, Ferritin superfamily, Metalloprotein, Oxidoreductase, X-ray crystallography
Original languageEnglish
Pages (from-to)849-861
JournalJournal of Biological Inorganic Chemistry
Volume24
Issue number6
Early online date2019
Publication statusPublished - 2019
Publication categoryResearch
Peer-reviewedYes