title: Light-harvesting Complexes (LHCs) Cluster Spontaneously in Membrane Environment Leading to Shortening of Their Excited State Lifetimes.
abstract: The light reactions of photosynthesis, which include light-harvesting and charge separation, take place in the amphiphilic environment of the thylakoid membrane. The light-harvesting complex II (LHCII) is the main responsible for light absorption in plants and green algae and is involved in photoprotective mechanisms that regulate the amount of excited states in the membrane. The dual function of LHCII has been extensively studied in detergent micelles, but recent results have indicated that the properties of this complex differ in a lipid environment. In this work we checked these suggestions by studying LHCII in liposomes. By combining bulk and single molecule measurements, we monitored the fluorescence characteristics of liposomes containing single complexes up to densely packed proteoliposomes. We show that the natural lipid environment per se does not alter the properties of LHCII, which for single complexes remain very similar to that in detergent. However, we show that LHCII has the strong tendency to cluster in the membrane and that protein interactions and the extent of crowding modulate the lifetimes of the excited state in the membrane. Finally, the presence of LHCII monomers at low concentrations of complexes per liposome is discussed.
authors.affiliation: From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
authors.forename: Alberto
authors.initials: A
authors.lastname: Natali
authors.affiliation: From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Gruber
authors.affiliation: Institute of Molecular Biosciences, Goethe-University Frankfurt/M, 60438 Frankfurt, Germany, and.
authors.forename: Lars
authors.initials: L
authors.lastname: Dietzel
authors.affiliation: Electron Microscopy, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands.
authors.forename: Marc C A
authors.initials: MC
authors.lastname: Stuart
authors.affiliation: From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands.
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
authors.affiliation: From the Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands, r.croce@vu.nl.
authors.forename: Roberta
authors.initials: R
authors.lastname: Croce
mesh_terms: D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D045342:Light-Harvesting Protein Complexes; D008563:Membrane Lipids
keywords: fluorescence; light-harvesting complex (antenna complex); liposomes; membrane; membrane protein; photosynthesis; single molecule spectroscopy; ultraviolet-visible spectroscopy (UV-visible spectroscopy)