title: Light regulation of CaS, a novel phosphoprotein in the thylakoid membrane of Arabidopsis thaliana.
abstract: Exposure of Arabidopsis thaliana plants to high levels of light revealed specific phosphorylation of a 40 kDa protein in photosynthetic thylakoid membranes. The protein was identified by MS as extracellular calcium-sensing receptor (CaS), previously reported to be located in the plasma membrane. By confocal laser scanning microscopy and subcellular fractionation, it was demonstrated that CaS localizes to the chloroplasts and is enriched in stroma thylakoids. The phosphorylation level of CaS responded strongly to light intensity. The light-dependent thylakoid protein kinase STN8 is required for CaS phosphorylation. The phosphorylation site was mapped to the stroma-exposed Thr380, located in a motif for interaction with 14-3-3 proteins and proteins with forkhead-associated domains, which suggests the involvement of CaS in stress responses and signaling pathways. The knockout Arabidopsis lines revealed a significant role for CaS in plant growth and development.
authors.affiliation: Department of Biology, Plant Physiology and Molecular Biology, University of Turku, Finland.
authors.forename: Julia P
authors.initials: JP
authors.lastname: Vainonen
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Sakuragi
authors.forename: Simon
authors.initials: S
authors.lastname: Stael
authors.forename: Mikko
authors.initials: M
authors.lastname: Tikkanen
authors.forename: Yagut
authors.initials: Y
authors.lastname: Allahverdiyeva
authors.forename: Virpi
authors.initials: V
authors.lastname: Paakkarinen
authors.forename: Eveliina
authors.initials: E
authors.lastname: Aro
authors.forename: Marjaana
authors.initials: M
authors.lastname: Suorsa
authors.forename: Henrik V
authors.initials: HV
authors.lastname: Scheller
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Vener
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D044169:Receptors, Calcium-Sensing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020524:Thylakoids / Q000378:metabolism*
chemical_list: D010750:Phosphoproteins; D044169:Receptors, Calcium-Sensing; D011494:Protein Kinases; C504925:STN8 protein, Arabidopsis