Capturing the Quenching Mechanism of Light-Harvesting Complexes of Plants by Zooming in on the Ensemble

Vincenzo Mascoli, Nicoletta Liguori, Pengqi Xu, Laura M. Roy, Ivo H.M. van Stokkum, Roberta Croce*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The light-harvesting complexes (LHCs) of plants can regulate the energy flux to the reaction centers in response to fluctuating light by virtue of their vast conformational landscape. They do so by switching from a light-harvesting state to a quenched state, dissipating the excess absorbed energy as heat. However, isolated LHCs are prevalently in their light-harvesting state, which makes the identification of their photoprotective mechanism extremely challenging. Here, ensemble time-resolved fluorescence experiments show that monomeric CP29, a minor LHC of plants, exists in various emissive states with identical spectra but different lifetimes. The photoprotective mechanism active in a subpopulation of strongly quenched complexes is further investigated via ultrafast transient absorption spectroscopy, kinetic modeling, and mutational analysis. We demonstrate that the observed quenching is due to excitation energy transfer from chlorophylls to a dark state of the centrally bound lutein.
Original languageEnglish
Pages (from-to)2900-2912
Number of pages13
Issue number11
Early online date29 Aug 2019
Publication statusPublished - 14 Nov 2019


  • antenna quenching
  • carotenoids
  • energy transfer
  • light harvesting
  • mutational analysis
  • photoprotection
  • photosynthesis
  • SDG15: Life on land
  • SDG7: Affordable and clean energy
  • target kinetic modeling
  • time-resolved electronic spectroscopy


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