Crystal structure of the Fenna-Matthews-Olson Protein from Chlorobaculum Tepidum

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.163 
  • R-Value Observed: 0.166 

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The structural basis for the difference in absorbance spectra for the FMO antenna protein from various green sulfur bacteria.

Tronrud, D.E.Wen, J.Gay, L.Blankenship, R.E.

(2009) Photosynth Res 100: 79-87

  • DOI: https://doi.org/10.1007/s11120-009-9430-6
  • Primary Citation of Related Structures:  
    3ENI, 3EOJ

  • PubMed Abstract: 

    The absorbance spectrum of the Fenna-Matthews-Olson protein--a component of the antenna system of Green Sulfur Bacteria--is always one of two types, depending on the species of the source organism. The FMO from Prosthecochloris aestuarii 2K has a spectrum of type 1 while that from Chlorobaculum tepidum is of type 2. The previously reported crystal structures for these two proteins did not disclose any rationale that would explain their spectral differences. We have collected a 1.3 A X-ray diffraction dataset of the FMO from Prosthecochloris aestuarii 2K, which has allowed us to identify an additional Bacteriochlorophyll-a molecule with chemical attachments to both sides of the central magnesium atom. A new analysis of the previously published X-ray data for the Chlorobaculum tepidum FMO shows the presence of a Bacteriochlorophyll-a molecule in an equivalent location but with a chemical attachment from only one side. This difference in binding is shown to be predictive of the spectral type of the FMO.

  • Organizational Affiliation

    Howard Hughes Medical Institute, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA. det101@daletronrud.com

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Bacteriochlorophyll a proteinA,
B [auth C]
365Chlorobaculum tepidumMutation(s): 0 
Find proteins for Q46393 (Chlorobaculum tepidum (strain ATCC 49652 / DSM 12025 / NBRC 103806 / TLS))
Explore Q46393 
Go to UniProtKB:  Q46393
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ46393
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on BCL

Download Ideal Coordinates CCD File 
C [auth A]
D [auth A]
E [auth A]
F [auth A]
G [auth A]
C [auth A],
D [auth A],
E [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A],
J [auth A],
K [auth C],
L [auth C],
M [auth C],
N [auth C],
O [auth C],
P [auth C],
Q [auth C],
R [auth C]
C55 H74 Mg N4 O6
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.163 
  • R-Value Observed: 0.166 
  • Space Group: P 43 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 169.1α = 90
b = 169.1β = 90
c = 169.1γ = 90
Software Package:
Software NamePurpose
PHENIXmodel building
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2009-05-12
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2024-02-21
    Changes: Data collection, Database references, Derived calculations