title: Functions of the water soluble chlorophyll-binding protein in plants.
abstract: Functional aspects of water soluble chlorophyll-binding protein (WSCP) in plants were investigated during the courses of leaf senescence, chlorophyll biogenesis, stress response and photoprotection. The cDNA sequence encoding WSCP from cauliflower was cloned into a binary vector to facilitate Agrobacterium tumefaciens mediated transformation of Nicotiana tabacum. The resultant transgenic tobacco plants overexpressed the CauWSCP gene under the control of a 35S-promoter. Analyses of protein and pigment contents indicate that WSCP overexpression does not enhance chlorophyll catabolism in vivo, thus rendering a role of WSCP in Chl degradation unlikely. Accumulation of higher levels of protochlorophyllide in WSCP overexpressor plants corroborates a proposed temporary storage and carrier function of WSCP for chlorophyll and late precursors. Although WSCP overexpressor plants did not show significant differences in non-photochemical quenching of chlorophyll fluorescence, they are characterized by significantly lower zeaxanthin accumulation and peroxidase activity at different light intensities, even at high light intensities of 700-900μmol photons m(-2)s(-1). These results suggest a photoprotective function of the functional chlorophyll binding-WSCP tetramer by shielding of chlorophylls from molecular oxygen.
authors.affiliation: Institut für Biologie/Pflanzenphysiologie, Humboldt-Universität zu Berlin, Philippstrasse 13, Gebäude 12, 115 Berlin, Germany.
authors.forename: Sridevi
authors.initials: S
authors.lastname: Damaraju
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schlede
authors.forename: Ulrich
authors.initials: U
authors.lastname: Eckhardt
authors.forename: Heiko
authors.initials: H
authors.lastname: Lokstein
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
mesh_terms: D001937:Brassica / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D055864:Droughts; D005453:Fluorescence; D018506:Gene Expression Regulation, Plant; D045342:Light-Harvesting Protein Complexes / Q000235:genetics / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D010545:Peroxides / Q000378:metabolism; D010936:Plant Extracts / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D012995:Solubility; D013312:Stress, Physiological / Q000235:genetics; D014867:Water / Q000378:metabolism*; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D010545:Peroxides; D010936:Plant Extracts; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D024341:Xanthophylls; D014867:Water; D002734:Chlorophyll; D009195:Peroxidase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase