Aggregation of Light-Harvesting Complex II leads to formation of efficient excitation energy traps in monomeric and trimeric complexes

Edited by Peter Brzezinski

Received 17 June 2007; accepted 27 June 2007. published online 05 July 2007.

Abstract

Non-photochemical quenching (NPQ) protects plants against photodamage by converting excess excitation energy into harmless heat. In vitro aggregation of the major light-harvesting complex (LHCII) induces similar quenching, the molecular mechanism of which is frequently considered to be the same. However, a very basic question regarding the aggregation-induced quenching has not been answered yet. Are excitation traps created upon aggregation, or do existing traps start quenching excitations more efficiently in aggregated LHCII where trimers are energetically coupled? Time-resolved fluorescence experiments presented here demonstrate that aggregation creates traps in a significant number of LHCII trimers, which subsequently also quench excitations in connected LHCIIs.

Abbreviations: β-DM, n-dodecyl-β,d-maltoside, Chl, chlorophyll, CI, confidence interval, LHCII, light-harvesting complex II, NPQ, non-photochemical quenching, PSII, photosystem II, RC, reaction centre

Keywords: LHCII, Non-photochemical quenching, Photosystem II, Picosecond fluorescence, Time-correlated single photon counting

a Wageningen University, Laboratory of Biophysics, Dreijenlaan 3, 6703HA Wageningen, The Netherlands

b Queen Mary University of London Mile End, School of Biological and Chemical Sciences, Bancroft Road, London E1 4NS, United Kingdom

c Microspectroscopy Centre Wageningen, Dreijenlaan 3, 6703HA Wageningen, The Netherlands

Corresponding author. Fax: +31 317 482725.

PII: S0014-5793(07)00727-2

doi:10.1016/j.febslet.2007.06.070

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