title: LHCII is an antenna of both photosystems after long-term acclimation.
abstract: LHCII, the most abundant membrane protein on earth, is the major light-harvesting complex of plants. It is generally accepted that LHCII is associated with Photosystem II and only as a short-term response to overexcitation of PSII a subset moves to Photosystem I, triggered by its phosphorylation (state1 to state2 transition). However, here we show that in most natural light conditions LHCII serves as an antenna of both Photosystem I and Photosystem II and it is quantitatively demonstrated that this is required to achieve excitation balance between the two photosystems. This allows for acclimation to different light intensities simply by regulating the expression of LHCII genes only. It is demonstrated that indeed the amount of LHCII that is bound to both photosystems decreases when growth light intensity increases and vice versa. Finally, time-resolved fluorescence measurements on the photosynthetic thylakoid membranes show that LHCII is even a more efficient light harvester when associated with Photosystem I than with Photosystem II.
authors.affiliation: Department of Physics and Astronomy, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
authors.forename: Emilie
authors.initials: E
authors.lastname: Wientjes
authors.forename: Herbert
authors.initials: H
authors.lastname: van Amerongen
authors.forename: Roberta
authors.initials: R
authors.lastname: Croce
mesh_terms: D000064:Acclimatization; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000502:physiology*; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex