Intrinsically unstructured phosphoprotein TSP9 regulates light harvesting in Arabidopsis thaliana.
Biochemistry
; 48(2): 499-509, 2009 Jan 20.
Article
em En
| MEDLINE
| ID: mdl-19113838
ABSTRACT
Thylakoid-soluble phosphoprotein of 9 kDa, TSP9, is an intrinsically unstructured plant-specific protein [Song, J., et al. (2006) Biochemistry 45, 15633-15643] with unknown function but established associations with light-harvesting proteins and peripheries of both photosystems [Hansson, M., et al. (2007) J. Biol. Chem. 282, 16214-16222]. To investigate the function of this protein, we used a combination of reverse genetics and biochemical and fluorescence measurement methods in Arabidopsis thaliana. Differential gene expression analysis of plants with a T-DNA insertion in the TSP9 gene using an array of 24000 Arabidopsis genes revealed disappearance of high light-dependent induction of a specific set of mostly signaling and unknown proteins. TSP9-deficient plants had reduced levels of in vivo phosphorylation of light-harvesting complex II polypeptides. Recombinant TSP9 was phosphorylated in light by thylakoid membranes isolated from the wild-type and mutant plants lacking STN8 protein kinase but not by the thylakoids deficient in STN7 kinase, essential for photosynthetic state transitions. TSP9-lacking mutant and RNAi plants with downregulation of TSP9 showed reduced ability to perform state transitions. The nonphotochemical quenching of chlorophyll fluorescence at high light intensities was also less efficient in the mutant compared to wild-type plants. Blue native electrophoresis of thylakoid membrane protein complexes revealed that TSP9 deficiency increased relative stability of photosystem II dimers and supercomplexes. It is concluded that TSP9 regulates plant light harvesting acting as a membrane-binding protein facilitating dissociation of light-harvesting proteins from photosystem II.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfoproteínas
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Arabidopsis
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Regulação da Expressão Gênica de Plantas
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Proteínas de Arabidopsis
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Complexos de Proteínas Captadores de Luz
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Suécia