Crystal structure of oxidised ferredoxin/flavodoxin NADP+ oxidoreductase 2 (FNR2) from Bacillus cereus

Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.207 
  • R-Value Observed: 0.210 

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The Characterization of Different Flavodoxin Reductase-Flavodoxin (FNR-Fld) Interactions Reveals an Efficient FNR-Fld Redox Pair and Identifies a Novel FNR Subclass.

Gudim, I.Hammerstad, M.Lofstad, M.Hersleth, H.P.

(2018) Biochemistry 57: 5427-5436

  • DOI: https://doi.org/10.1021/acs.biochem.8b00674
  • Primary Citation of Related Structures:  
    6GAQ, 6GAR, 6GAS

  • PubMed Abstract: 

    Flavodoxins (Flds) are small, bacterial proteins that transfer electrons to various redox enzymes. Flavodoxins are reduced by ferredoxin/flavodoxin NADP + oxidoreductases (FNRs), but little is known of the FNR-Fld interaction. Here, we compare the interactions of two flavodoxins (Fld1-2), one flavodoxin-like protein (NrdI), and three different thioredoxin reductase (TrxR)-like FNRs (FNR1-3), all from Bacillus cereus. Steady-state kinetics shows that the FNR2-Fld2 electron transfer pair is particularly efficient, and redox potential measurements also indicate that this is the most favorable electron donor/acceptor pair. Furthermore, crystal structures of FNR1 and FNR2 show that the proteins have crystallized in different conformations, a closed and an open conformation, respectively. We suggest that a large-scale conformational rearrangement takes place during the FNR catalytic cycle to allow for the binding and reduction of the Fld and, subsequently, the re-reduction of the FNR by NADPH. Finally, inspection of the residues surrounding the FAD cofactor in the FNR active site shows that a key isoalloxazine ring-stacking residue is different in FNR1 and FNR2, which could explain the large difference in catalytic efficiency between the two FNRs. To date, all of the characterized TrxR-like FNRs have a residue with aromatic character stacking against the FAD isoalloxazine ring, and this has been thought to be a conserved feature of this class of FNRs. FNR1, however, has a valine in this position. Bioinformatic analysis shows that the TrxR-like FNRs can actually be divided into two groups, one group where the FAD-stacking residue has aromatic character and another group where it is valine.

  • Organizational Affiliation

    Department of Biosciences, Section for Biochemistry and Molecular Biology , University of Oslo , Oslo 0316 , Norway.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ferredoxin--NADP reductase
A, B, C, D
331Bacillus cereus ATCC 14579Mutation(s): 0 
Gene Names: BC_4926
Find proteins for Q816D9 (Bacillus cereus (strain ATCC 14579 / DSM 31 / CCUG 7414 / JCM 2152 / NBRC 15305 / NCIMB 9373 / NCTC 2599 / NRRL B-3711))
Explore Q816D9 
Go to UniProtKB:  Q816D9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ816D9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.207 
  • R-Value Observed: 0.210 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 109.66α = 90
b = 109.66β = 90
c = 242.519γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Research Council of NorwayNorway231669

Revision History  (Full details and data files)

  • Version 1.0: 2018-09-05
    Type: Initial release
  • Version 1.1: 2018-09-19
    Changes: Data collection, Database references
  • Version 1.2: 2018-09-26
    Changes: Data collection, Database references
  • Version 1.3: 2024-01-17
    Changes: Data collection, Database references, Derived calculations, Refinement description