title: β-Carotene influences the phycobilisome antenna of cyanobacterium Synechocystis sp. PCC 6803.
abstract: We investigated the relation between the carotenoid composition and the structure of phycobilisome (PBS) antenna of cyanobacterium Synechocystis sp. PCC 6803. PBS is a large soluble protein complex enhances the light harvesting efficiency of the cells. It is composed of a central allophycocyanin core and radial phycocyanin rods, but it does not contain carotenoids. However, the absence or low level of carotenoids were previously shown to lead the co-existence of unconnected rod units and assembled PBS with shorter peripheral rods. Here we show that the lack of β-carotene, but not of xanthophylls or the distortion of photosystem structure, evoked unconnected rods. Thus, these essential β-carotene molecules are not bound by Photosystem I or Photosystem II. Our results do not show correlation between the reactive oxygen species (ROS) and PBS distortion despite the higher singlet oxygen producing capacity and light sensitivity of the mutant cells. Reduced cellular level of those linker proteins attaching the rod units together was also observed, but the direct damage of the linkers by ROS are not supported by our data. Enzymatic PBS proteolysis induced by nitrogen starvation in carotenoid mutant cells revealed a retarded degradation of the unconnected rod units.
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: Sindhujaa
authors.initials: S
authors.lastname: Vajravel
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Kovács
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Kis
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: Ateeq Ur
authors.initials: AU
authors.lastname: Rehman
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Gombos
authors.affiliation: Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, Szeged, 6701, Hungary. toth.tunde@brc.mta.hu.
authors.forename: Tunde N
authors.initials: TN
authors.lastname: Toth
mesh_terms: D005947:Glucose / Q000378:metabolism; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000187:drug effects* / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D045524:Phycobilisomes / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D013050:Spectrometry, Fluorescence; D046939:Synechocystis / Q000187:drug effects* / Q000502:physiology; D019207:beta Carotene / Q000494:pharmacology*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; D019207:beta Carotene; D005947:Glucose; D009584:Nitrogen
keywords: Carotenoids; Cyanobacteria; Photosynthesis; Phycobilisome degradation