Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-bindmg light-harvesting complexes of Chlorella fusca with different pigment compositions and pigment-protein stoichiometries

Monika Meyer, Christian Wilhelm, Gyözö Garab

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Abstract

Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll a/b-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region. Reconstituted complexes, independent of their pigment composition, exhibited the most characteristic circular dichroism bands of the native light-harvesting complex, even if one polypeptide bound only 3 chlorophyll a, 3 chlorophyll b and 1-2 xanthophyll molecules. Full restoration of the protein secondary structure, however, could not be achieved. The α-helix content depended significantly on the pigment composition as well as on the pigment-protein ratio of the reconstituted complexes. Further binding of pigments resulted in restoration of the minor excitonic circular dichroism bands, the amplitudes of which depended on the pigment content of the reconstituted complexes. These data suggest that in the reconstitution of light-harvesting complexes a 'central cluster' of pigment molecules plays an important role. Further binding of pigments to the 'peripheral binding sites' appeared also to stabilize the protein secondary structure of the reconstituted complexes.

Original languageEnglish
Pages (from-to)71-81
Number of pages11
JournalPhotosynthesis Research
Volume49
Issue number1
Publication statusPublished - 1996

Fingerprint

Chlorella
light harvesting complex
stoichiometry
Circular Dichroism
Pigments
Stoichiometry
pigments
Secondary Protein Structure
chlorophyll
Light
Chemical analysis
circular dichroism spectroscopy
Proteins
proteins
Xanthophylls
Chlorophyta
protein secondary structure
Binding Sites
Peptides
Restoration

Keywords

  • Algae
  • Circular dichroism
  • Light-harvesting complex
  • Pigment-pigment interaction
  • Protein secondary structure
  • Reconstitution

ASJC Scopus subject areas

  • Plant Science

Cite this

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title = "Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-bindmg light-harvesting complexes of Chlorella fusca with different pigment compositions and pigment-protein stoichiometries",
abstract = "Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll a/b-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region. Reconstituted complexes, independent of their pigment composition, exhibited the most characteristic circular dichroism bands of the native light-harvesting complex, even if one polypeptide bound only 3 chlorophyll a, 3 chlorophyll b and 1-2 xanthophyll molecules. Full restoration of the protein secondary structure, however, could not be achieved. The α-helix content depended significantly on the pigment composition as well as on the pigment-protein ratio of the reconstituted complexes. Further binding of pigments resulted in restoration of the minor excitonic circular dichroism bands, the amplitudes of which depended on the pigment content of the reconstituted complexes. These data suggest that in the reconstitution of light-harvesting complexes a 'central cluster' of pigment molecules plays an important role. Further binding of pigments to the 'peripheral binding sites' appeared also to stabilize the protein secondary structure of the reconstituted complexes.",
keywords = "Algae, Circular dichroism, Light-harvesting complex, Pigment-pigment interaction, Protein secondary structure, Reconstitution",
author = "Monika Meyer and Christian Wilhelm and Gy{\"o}z{\"o} Garab",
year = "1996",
language = "English",
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journal = "Photosynthesis Research",
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T1 - Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-bindmg light-harvesting complexes of Chlorella fusca with different pigment compositions and pigment-protein stoichiometries

AU - Meyer, Monika

AU - Wilhelm, Christian

AU - Garab, Gyözö

PY - 1996

Y1 - 1996

N2 - Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll a/b-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region. Reconstituted complexes, independent of their pigment composition, exhibited the most characteristic circular dichroism bands of the native light-harvesting complex, even if one polypeptide bound only 3 chlorophyll a, 3 chlorophyll b and 1-2 xanthophyll molecules. Full restoration of the protein secondary structure, however, could not be achieved. The α-helix content depended significantly on the pigment composition as well as on the pigment-protein ratio of the reconstituted complexes. Further binding of pigments resulted in restoration of the minor excitonic circular dichroism bands, the amplitudes of which depended on the pigment content of the reconstituted complexes. These data suggest that in the reconstitution of light-harvesting complexes a 'central cluster' of pigment molecules plays an important role. Further binding of pigments to the 'peripheral binding sites' appeared also to stabilize the protein secondary structure of the reconstituted complexes.

AB - Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll a/b-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region. Reconstituted complexes, independent of their pigment composition, exhibited the most characteristic circular dichroism bands of the native light-harvesting complex, even if one polypeptide bound only 3 chlorophyll a, 3 chlorophyll b and 1-2 xanthophyll molecules. Full restoration of the protein secondary structure, however, could not be achieved. The α-helix content depended significantly on the pigment composition as well as on the pigment-protein ratio of the reconstituted complexes. Further binding of pigments resulted in restoration of the minor excitonic circular dichroism bands, the amplitudes of which depended on the pigment content of the reconstituted complexes. These data suggest that in the reconstitution of light-harvesting complexes a 'central cluster' of pigment molecules plays an important role. Further binding of pigments to the 'peripheral binding sites' appeared also to stabilize the protein secondary structure of the reconstituted complexes.

KW - Algae

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