title: Spermine is a potent modulator of proton transport through LHCII.
abstract: The effect of spermine on proton transport across large unilamellar liposomes containing incorporated complexes of the PSII antenna has been studied with the application of a pH-sensitive dye entrapped inside the vesicles. Both monomeric LHCbs and trimeric LHCII increased the permeability of proteoliposomes to protons when in a partly aggregated state within the lipid membrane. We have previously shown that a spermine-induced conformational change in LHCII results in its aggregation and ultimately in the enhancement of excitation energy as heat (qE). In this paper, spermine-induced aggregation of LHCII was found to facilitate proton transport across the proteoliposomes, indicating that a second protective mechanism (other than qE) might exist and might be regulated in vivo by polyamines when photosynthesis is saturated in excess light.
authors: Department of Biology, University of Crete, Voutes University Campus, GR-70013 Heraklion, Crete, Greece.
authors: Theodoros
authors: T
authors: Tsiavos
authors: Department of Biology, University of Crete, Voutes University Campus, GR-70013 Heraklion, Crete, Greece.
authors: Nikolaos E
authors: NE
authors: Ioannidis
authors: Institute of Molecular Biology and Biotechnology, FORTH, GR-70013 Heraklion, Crete, Greece.
authors: Achilleas
authors: A
authors: Tsortos
authors: Department of Biology, University of Crete, Voutes University Campus, GR-70013 Heraklion, Crete, Greece; Institute of Molecular Biology and Biotechnology, FORTH, GR-70013 Heraklion, Crete, Greece.
authors: Electra
authors: E
authors: Gizeli
authors: Department of Biology, University of Crete, Voutes University Campus, GR-70013 Heraklion, Crete, Greece. Electronic address: kotzab@biology.uoc.gr.
authors: Kiriakos
authors: K
authors: Kotzabasis
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D017136:Ion Transport; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism; D011522:Protons; D013096:Spermine / Q000378:metabolism*; D018724:Spinacia oleracea / Q000378:metabolism*
chemical_list: D045342:Light-Harvesting Protein Complexes; D011510:Proteolipids; D011522:Protons; C020485:proteoliposomes; D013096:Spermine
keywords: Aggregation; Light harvesting complex II; Liposomes; Proton permeability; Spermine