title: Leaf C40.4: a carotenoid-associated protein involved in the modulation of photosynthetic efficiency?
abstract: Comparative analysis by differential RNA display (DDRT-PCR) of the expression patterns of potato plants induced and non-induced to tuberize, led to the isolation of a cDNA clone, C40.4, that is strongly upregulated in the leaves of tuberizing plants. Leaf expression of this transcript was shown to be light-dependent, with increased levels of mRNA and protein being detected during the light hours. Sequence analysis revealed near complete identity to potato CDSP34, a thylakoid protein induced by drought stress, and strong homology to the carotenoid-associated proteins fibrillin, ChrB and PAP from pepper fruit, and CHRC from cucumber flowers. By using an antibody against pepper fibrillin, we were able to demonstrate a chloroplastic location of the C40.4 protein in association with the thylakoid membranes. Two-dimensional analysis of thylakoid pigment-protein complexes showed a specific association of the protein with the photosystem II (PSII) multi-subunit complex. Antisense plants with reduced levels of accumulation of C40.4 showed a stunted growth and decreased tuber yield and exhibited reduced values of non-photochemical quenching of chlorophyll a fluorescence. Altogether, these results indicate a preferential association of the C40.4 protein with the light harvesting complex of photosystem II (LHCII) antenna pigment complexes, and suggest a functional role of this protein in photosynthesis, by modulating photosynthetic efficiency and dissipation of excess absorbed light energy within the antenna complex.
authors.affiliation: Departament de Genética Molecular, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Cientificas, Barcelona, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Monte
authors.forename: D
authors.initials: D
authors.lastname: Ludevid
authors.forename: S
authors.initials: S
authors.lastname: Prat
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002338:Carotenoids / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D016372:RNA, Antisense / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D015854:Up-Regulation
chemical_list: C401412:C40.4 protein, Solanum demissum; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D010940:Plant Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D002734:Chlorophyll; D002338:Carotenoids; D000077194:Chlorophyll A