Abstract
The Fenna–Matthews–Olson antenna protein from the green bacterium Pelodictyon phaeum mediates the energy transfer from a peripheral antenna complex to the membrane-bound reaction center. The three-dimensional structure of this protein has been previously modeled using X-ray diffraction to a resolution limit of 2.0 Å, with R work and R free values of 16.6 and 19.9 %, respectively (Larson et al., Photosynth Res 107:139–150, 2011). This model shows the protein as consisting of β-sheets surrounding several bacteriochlorophyll cofactors. While most of the model clearly matches the electron density maps, in this paper we re-examine the electron density for a specific feature, namely the eighth bacteriochlorophyll a cofactor. This electron density is now interpreted as arising primarily from the end of an otherwise disordered polyethylene glycol molecule. Additional electron density is present but the density is weak and cannot be unambiguously assigned. The new model has R work and R free values of 16.2 and 19.0 %, respectively.
Abbreviations
- FMO:
-
Fenna–Matthews–Olson
- Bchl-a :
-
Bacteriochlorophyll a
- PEG:
-
Polyethylene glycol
References
Adams PD, Grosse-Kunstleve RW, Hung LW, Ioerger TR, McCoy AJ, Mariarty NW, Read RJ, Sacchettini JC, Sauter NK, Terwilliger TC (2002) PHENIX: building new software for automated crystallographic structure determination. Acta Crystallogr D58:1948–1954
Ben-Shem A, Frolow F, Nelson N (2004) Evolution of photosystem I-from symmetry through pseudosymmetry to asymmetry. FEBS Lett 564:274–280
Blankenship RE (2002) Molecular mechanisms of photosynthesis. Wiley-Blackwell, Malden
Bricogne G, Blanc E, Brandl M, Flensburg C, Keller P, Paciorek W, Roversi P, Smart OS, Vonrhein C, Womack TO (2009) Buster, version 2.8.0. Global Phasing Ltd., Cambridge
Brixner T, Stenger J, Vaswani HM, Cho M, Blankenship RE, Fleming GR (2005) Two-dimensional spectroscopy of electronic couplings in photosynthesis. Nature 434:625–628
Camara-Artigas A, Blankenship RE, Allen JP (2003) The structure of the FMO protein from Chlorobium tepidum at 2.2 Å resolution. Photosynth Res 75:49–55
Emsley P, Cowtan K (2004) Coot: model-building tools for molecular graphics. Acta Crystallogr D 60:2126–2132
Larson CR, Seng CO, Lauman L, Matthies HJ, Wen J, Blankenship RE, Allen JP (2011) The three dimensional structure of the FMO protein from Pelodictyon phaeum and the implications for energy transfer. Photosynth Res 107:139–150
Li YF, Zhou W, Blankenship RE, Allen JP (1997) Crystal structure of the bacteriochlorophyll a protein from Chlorobium tepidum. J Mol Biol 271:456–471
Matthews BW, Fenna RE, Bolognesi MC, Schmid MF, Olson JM (1979) Structure of a bacteriochlorophyll a-protein from the green photosynthetic bacterium Prosthecochloris aestuarii. J Mol Biol 131:259–285
Milder MTW, Brüggemann B, van Grondelle R, Herek JL (2010) Revisiting the optical properties of the FMO protein. Photosynth Res 104:257–274
Olson JM (1978) Bacteriochlorophyll a-proteins from green bacteria. In: Clayton RK, Sistrom WR (eds) The photosynthetic bacteria. Plenum Press, New York, pp 161–178
Olson JM (2004) The FMO protein. Photosynth Res 80:181–187
Oostergetel GT, Reus M, Chew AGM, Bryant DA, Boekema EJ, Holzwarth AR (2007) Long-range organization by bacteriochlorophyll in chlorosomes of Chlorobium tepidum investigated by cryo-electron microscopy. FEBS Lett 581:5435–5439
Panitchayangkoon G, Hayes D, Fransted KA, Caram JR, Harel E, Wen J, Blankenship RE, Engel GS (2010) Long-lived quantum coherence in photosynthetic complexes at physiological temperature. Proc Natl Acad Sci USA 107:12766–12770
Psencik J, Ikonen TP, Laurinmäki P, Merckel MC, Butcher SJ, Serimaa RE, Tuma R (2004) Lamella organization of pigments in chlorosomes, the light harvesting complexes of green photosynthetic bacteria. Biophys J 87:1165–1172
Read EL, Engel GS, Calhoun TR, Mančal T, Ahn TK, Blankenship RE, Fleming GR (2007) Cross-peak-specific two-dimensional electronic spectroscopy. Proc Natl Acad Sci USA 104:14203–14208
Staehelin LA, Golecki JR, Drews G (1980) Supermolecular organization of chlorosomes (Chlorobium vesicles) and their membrane attachment sites in Chlorobium limicola. Biochim Biophys Acta 589:30–45
Tronrud DE, Schmid MF, Matthews BW (1986) Structure and X-ray amino acid sequence of a bacteriochlorophyll a protein from Prosthecochloris aestuarii at 1.9 Å resolution. J Mol Biol 188:443–454
Tronrud DE, Wen J, Gay L, Blankenship RE (2009) The structural basis for the difference in absorbance spectra for the FMO antenna protein from various green sulfur bacteria. Photosynth Res 100:79–87
Wen J, Zhang H, Gross ML, Blankenship RE (2009) Membrane orientation of the FMO antenna protein from Chlorobaculum tepidum as determined by mass spectroscopy-based footprinting. Proc Natl Acad Sci USA 106:6134–6139
Acknowledgment
This work was supported by grant CHE 1158552 from the National Science Foundation.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tronrud, D.E., Allen, J.P. Reinterpretation of the electron density at the site of the eighth bacteriochlorophyll in the FMO protein from Pelodictyon phaeum . Photosynth Res 112, 71–74 (2012). https://doi.org/10.1007/s11120-012-9735-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11120-012-9735-8