Dynamics and mechanism of light harvesting in UV photoreceptor UVR8

Xiankun Li, Zheyun Liu, Haisheng Ren, Mainak Kundu, Lijuan Wang, Jiali Gao, Dongping Zhong

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Photosynthetic pigments form light-harvesting networks to enable nearly perfect quantum efficiency in photosynthesis via excitation energy transfer. However, similar light-harvesting mechanisms have not been reported in light sensing processes in other classes of photoreceptors during light-mediated signaling. Here, based on our earlier report, we mapped out a striking energy-transfer network composed of 26 structural tryptophan residues in the plant UV-B photoreceptor UVR8. The spectra of the tryptophan chromophores are tuned by the protein environments, funneling all excitation energy to a cluster of four tryptophan residues, a pyramid center, where the excitation-induced monomerization is initiated for cell signaling. With extensive site-directed mutagenesis, various time-resolved fluorescence techniques, and combined QM/MM simulations, we determined the energy-transfer rates for all donor-acceptor pairs, revealing the time scales from tens of picoseconds to nanoseconds. The overall light harvesting quantum efficiency by the pyramid center is significantly increased to 73%, compared to a direct excitation probability of 35%. UVR8 is the only photoreceptor discovered so far using a natural amino-acid tryptophan without utilizing extrinsic chromophores to form a network to carry out both light harvesting and light perception for biological functions.

Original languageEnglish (US)
Pages (from-to)12553-12569
Number of pages17
JournalChemical Science
Volume11
Issue number46
DOIs
StatePublished - Dec 14 2020

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry.

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