Different carotenoid conformations have distinct functions in light-harvesting regulation in plants

N. Liguori, P. Xu, Ivo van Stokkum, Bart van Oort, Yinghong Lu, Daniel Karcher, Ralph Bock, Roberta Croce

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

To avoid photodamage plants regulate the amount of excitation energy in the membrane at the level of the light-harvesting complexes (LHCs). It has been proposed that the energy absorbed in excess is dissipated via protein conformational changes of individual LHCs. However, the exact quenching mechanism remains unclear. Here we study the mechanism of quenching in LHCs that bind a single carotenoid species and are constitutively in a dissipative conformation. Via femtosecond spectroscopy we resolve a number of carotenoid dark states, demonstrating that the carotenoid is bound to the complex in different conformations. Some of those states act as excitation energy donors for the chlorophylls, whereas others act as quenchers. Via in silico analysis we show that structural changes of carotenoids are expected in the LHC protein domains exposed to the chloroplast lumen, where acidification triggers photoprotection in vivo. We propose that structural changes of LHCs control the conformation of the carotenoids, thus permitting access to different dark states responsible for either light harvesting or photoprotection.
Original languageEnglish
Article number1994
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 8 Dec 2017

Fingerprint

carotenoids
Carotenoids
Conformations
Light
Excitation energy
Quenching
Light-Harvesting Protein Complexes
quenching
Acidification
chloroplasts
proteins
Chlorophyll
lumens
chlorophylls
Chloroplasts
Computer Simulation
excitation
energy
Spectroscopy
Spectrum Analysis

Keywords

  • Bioenergetics
  • LHCII
  • Quenching
  • Carotenoids
  • Ultrafast Spectroscopy
  • Molecular dynamics
  • Target Analysis
  • astaxanthin

Cite this

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title = "Different carotenoid conformations have distinct functions in light-harvesting regulation in plants",
abstract = "To avoid photodamage plants regulate the amount of excitation energy in the membrane at the level of the light-harvesting complexes (LHCs). It has been proposed that the energy absorbed in excess is dissipated via protein conformational changes of individual LHCs. However, the exact quenching mechanism remains unclear. Here we study the mechanism of quenching in LHCs that bind a single carotenoid species and are constitutively in a dissipative conformation. Via femtosecond spectroscopy we resolve a number of carotenoid dark states, demonstrating that the carotenoid is bound to the complex in different conformations. Some of those states act as excitation energy donors for the chlorophylls, whereas others act as quenchers. Via in silico analysis we show that structural changes of carotenoids are expected in the LHC protein domains exposed to the chloroplast lumen, where acidification triggers photoprotection in vivo. We propose that structural changes of LHCs control the conformation of the carotenoids, thus permitting access to different dark states responsible for either light harvesting or photoprotection.",
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Different carotenoid conformations have distinct functions in light-harvesting regulation in plants. / Liguori, N.; Xu, P.; van Stokkum, Ivo; van Oort, Bart; Lu, Yinghong; Karcher, Daniel; Bock, Ralph; Croce, Roberta.

In: Nature Communications, Vol. 8, No. 1, 1994, 08.12.2017.

Research output: Contribution to JournalArticleAcademicpeer-review

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AU - Liguori, N.

AU - Xu, P.

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AU - Lu, Yinghong

AU - Karcher, Daniel

AU - Bock, Ralph

AU - Croce, Roberta

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AB - To avoid photodamage plants regulate the amount of excitation energy in the membrane at the level of the light-harvesting complexes (LHCs). It has been proposed that the energy absorbed in excess is dissipated via protein conformational changes of individual LHCs. However, the exact quenching mechanism remains unclear. Here we study the mechanism of quenching in LHCs that bind a single carotenoid species and are constitutively in a dissipative conformation. Via femtosecond spectroscopy we resolve a number of carotenoid dark states, demonstrating that the carotenoid is bound to the complex in different conformations. Some of those states act as excitation energy donors for the chlorophylls, whereas others act as quenchers. Via in silico analysis we show that structural changes of carotenoids are expected in the LHC protein domains exposed to the chloroplast lumen, where acidification triggers photoprotection in vivo. We propose that structural changes of LHCs control the conformation of the carotenoids, thus permitting access to different dark states responsible for either light harvesting or photoprotection.

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KW - Target Analysis

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