| | The Lhcb protein and xanthophyll composition of the light harvesting antenna controls the ΔpH-dependency of non-photochemical quenching in Arabidopsis thalianaEdited by Peter Brzezinski Received 2 March 2008; received in revised form 21 March 2008; accepted 26 March 2008. published online 07 April 2008. Abstract Nonphotochemical quenching (NPQ) is the photoprotective dissipation of energy in photosynthetic membranes. The hypothesis that the ΔpH-dependent component of NPQ (qE) component of non-photochemical quenching is controlled allosterically by the xanthophyll cycle has been tested using Arabidopsis mutants with different xanthophyll content and composition of Lhcb proteins. The titration curves of qE against ΔpH were different in chloroplasts containing zeaxanthin or violaxanthin, proving their roles as allosteric activator and inhibitor, respectively. The curves differed in mutants deficient in lutein and specific Lhcb proteins. The results show that qE is determined by xanthophyll occupancy and the structural interactions within the antenna that govern allostericity. Abbrevations: 9aa, 9-aminoacridine, DES, de-epoxidation state of the xanthophyll cycle pool, LHCII, light harvesting complexes of photosystem II, Lhcb, the proteins of LHCII, NPQ, non-photochemical quenching, ΔpH, pH difference across the thylakoid membrane, PSII, photosystem II, q9aa, quenching of 9aa fluorescence, qE, the ΔpH-dependent component of NPQ, WT, wild-type, zea, zeaxanthin a Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom b School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, Bancroft Road, London E1 4NS, United Kingdom  Corresponding author.
PII: S0014-5793(08)00287-1 doi:10.1016/j.febslet.2008.03.040 © 2008 Federation of European Biochemical Societies. Published by Elsevier BV. All rights reserved. | |
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ABSTRACT
