Photosynthesis Research

, Volume 100, Issue 2, pp 79–87

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

  • Dale E. Tronrud
  • Jianzhong Wen
  • Leslie Gay
  • Robert E. Blankenship
Regular Paper

DOI: 10.1007/s11120-009-9430-6

Cite this article as:
Tronrud, D.E., Wen, J., Gay, L. et al. Photosynth Res (2009) 100: 79. doi:10.1007/s11120-009-9430-6

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 Å 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.

Keywords

FMO Bacteriochlorophyll Crystal structure Absorbance spectra Bidentate ligation 

Abbreviations

Bchl-a

Bacteriochlorophyll-a

Cbl

Chlorobaculum

FMO

Fenna–Matthews–Olson Protein

PDB

Protein Data Bank

Pel

Pelodictyon

Ptc

Prosthecochloris

r.m.s.

Root mean square

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Dale E. Tronrud
    • 1
    • 3
  • Jianzhong Wen
    • 2
  • Leslie Gay
    • 1
  • Robert E. Blankenship
    • 2
  1. 1.Howard Hughes Medical Institute, Institute of Molecular BiologyUniversity of OregonEugeneUSA
  2. 2.Departments of Biology and ChemistryWashington UniversitySt LouisUSA
  3. 3.Department of Biochemistry and BiophysicsOregon State UniversityCorvallisUSA

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