3ENI : Crystal structure of the Fenna-Matthews-Olson Protein from Chlorobaculum Tepidum

  • Dale E. Tronrud (Contributor)
  • R. E. Blankenship (Contributor)
  • James Allen (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2009-05-12
Deposition Date:2008-09-25
Revision Date:2011-07-13
Molecular Weight:95008.53
Macromolecule Type:Protein
Residue Count:730
Atom Site Count:6567

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.
Date made available2009

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