title: Antisense inhibition of the photosynthetic antenna proteins CP29 and CP26: implications for the mechanism of protective energy dissipation.
abstract: The specific roles of the chlorophyll a/b binding proteins CP29 and CP26 in light harvesting and energy dissipation within the photosynthetic apparatus have been investigated. Arabidopsis was transformed with antisense constructs against the genes encoding the CP29 or CP26 apoprotein, which gave rise to several transgenic lines with remarkably low amounts of the antisense target proteins. The decrease in the level of CP24 protein in the CP29 antisense lines indicates a physical interaction between these complexes. Analysis of chlorophyll fluorescence showed that removal of the proteins affected photosystem II function, probably as a result of changes in the organization of the light-harvesting antenna. However, whole plant measurements showed that overall photosynthetic rates were similar to those in the wild type. Both antisense lines were capable of the qE type of nonphotochemical fluorescence quenching, although there were minor changes in the capacity for quenching and in its induction kinetics. High-light-induced violaxanthin deepoxidation to zeaxanthin was not affected, although the pool size of these pigments was decreased slightly. We conclude that CP29 and CP26 are unlikely to be sites for nonphotochemical quenching.
authors.affiliation: Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-901 87 Umeå, Sweden. jenny.anderson@plantphys.umu.se
authors.forename: J
authors.initials: J
authors.lastname: Andersson
authors.forename: R G
authors.initials: RG
authors.lastname: Walters
authors.forename: P
authors.initials: P
authors.lastname: Horton
authors.forename: S
authors.initials: S
authors.lastname: Jansson
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000528:radiation effects; D029681:Arabidopsis Proteins; D002338:Carotenoids / Q000378:metabolism; D061146:Chlorophyll Binding Proteins; D002736:Chloroplasts / Q000378:metabolism* / Q000528:radiation effects; D016373:DNA, Antisense; D004735:Energy Transfer / Q000502:physiology*; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D020524:Thylakoids / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C069660:CP29 light harvesting complex; D061146:Chlorophyll Binding Proteins; D016373:DNA, Antisense; C490432:LHCB5 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D002338:Carotenoids