Title: Two mechanisms for dissipation of excess light in monomeric and trimeric light-harvesting complexes

Abstract

Oxygenic photoautotrophs require mechanisms for rapidly matching the level of chlorophyll excited states from light harvesting with the rate of electron transport from water to carbon dioxide. These photoprotective reactions prevent formation of reactive excited states and photoinhibition. The fastest response to excess illumination is the so-called non-photochemical quenching which, in higher plants, requires the luminal pH sensor PsbS and other yet unidentified components of the photosystem II antenna. Both trimeric light-harvesting complex II (LHCII) and monomeric LHC proteins have been indicated as site(s) of the heat-dissipative reactions. Different mechanisms have been proposed: Energy transfer to a lutein quencher in trimers, formation of a zeaxanthin radical cation in monomers. Here, we report on the construction of a mutant lacking all monomeric LHC proteins but retaining LHCII trimers. Its non-photochemical quenching induction rate was substantially slower with respect to the wild type. A carotenoid radical cation signal was detected in the wild type, although it was lost in the mutant. Here, we conclude that non-photochemical quenching is catalysed by two independent mechanisms, with the fastest activated response catalysed within monomeric LHC proteins depending on both zeaxanthin and lutein and on the formation of a radical cation. Trimeric LHCII was responsible formore » the slowly activated quenching component whereas inclusion in supercomplexes was not required. Finally, this latter activity does not depend on lutein nor on charge transfer events, whereas zeaxanthin was essential.« less

Authors:

Dall'Osto, Luca  ^[1];

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Cazzaniga, Stefano ^[1]; Bressan, Mauro ^[1]; Paleček, David ^[2]; Židek, Karel ^[2]; Niyogi, Krishna K. ^[3]; Fleming, Graham R. ^[4]; Zigmantas, Donatas ^[2]; Bassi, Roberto  ^[5]

• Search OSTI.GOV for author "Bassi, Roberto"
• Search OSTI.GOV for ORCID "0000-0002-4140-8446"
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+ Show Author Affiliations

1. Univ. di Verona, Verona (Italy). Dipartimento di Biotecnologie
2. Lund Univ. (Sweden). Dept. of Chemical Physics
3. Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst., Dept. of Plant and Microbial Biology; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry, Graduate Group in Applied Science and Technology
5. Univ. di Verona, Verona (Italy). Dipartimento di Biotecnologie; Consiglio Nazionale delle Ricerche (CNR), Firenze (Italy). Istituto per la Protezione delle Piante (IPP)

Publication Date:

2017-04-10

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)

OSTI Identifier:

1393220

DOE Contract Number:  

AC02-05CH11231

Resource Type:

Journal Article

Journal Name:

Nature Plants

Additional Journal Information:

Journal Volume: 3; Journal Issue: 5; Journal ID: ISSN 2055-0278

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

Antenna complex; Non-photochemical quenching