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The PPH1 phosphatase is specifically involved in LHCII dephosphorylation and state transitions in Arabidopsis

Ingelsson, Björn
Andres, Charles
Kessler, Felix
Vener, Alexander V
Published in Proceedings of the National Academy of Sciences. 2010, vol. 107, no. 10, p. 4782-7
Abstract The ability of plants to adapt to changing light conditions depends on a protein kinase network in the chloroplast that leads to the reversible phosphorylation of key proteins in the photosynthetic membrane. Phosphorylation regulates, in a process called state transition, a profound reorganization of the electron transfer chain and remodeling of the thylakoid membranes. Phosphorylation governs the association of the mobile part of the light-harvesting antenna LHCII with either photosystem I or photosystem II. Recent work has identified the redox-regulated protein kinase STN7 as a major actor in state transitions, but the nature of the corresponding phosphatases remained unknown. Here we identify a phosphatase of Arabidopsis thaliana, called PPH1, which is specifically required for the dephosphorylation of light-harvesting complex II (LHCII). We show that this single phosphatase is largely responsible for the dephosphorylation of Lhcb1 and Lhcb2 but not of the photosystem II core proteins. PPH1, which belongs to the family of monomeric PP2C type phosphatases, is a chloroplast protein and is mainly associated with the stroma lamellae of the thylakoid membranes. We demonstrate that loss of PPH1 leads to an increase in the antenna size of photosystem I and to a strong impairment of state transitions. Thus phosphorylation and dephosphorylation of LHCII appear to be specifically mediated by the kinase/phosphatase pair STN7 and PPH1. These two proteins emerge as key players in the adaptation of the photosynthetic apparatus to changes in light quality and quantity.
Keywords Arabidopsis/genetics/metabolismArabidopsis Proteins/classification/genetics/metabolismChlorophyll/metabolismChloroplasts/metabolismElectron TransportGreen Fluorescent Proteins/genetics/metabolismImmunoblottingMicroscopyConfocalMutationPhosphoprotein Phosphatases/classification/genetics/metabolismPhosphorylationPhotosystem II Protein Complex/genetics/metabolismPhylogenyPlant Leaves/genetics/metabolismProtein Kinases/genetics/metabolismProtein-Serine-Threonine KinasesReverse Transcriptase Polymerase Chain ReactionSpectrometryFluorescenceThylakoids/metabolism
PMID: 20176943
Full text
Research group Génétique moléculaire des chloroplastes
Projects FNS: 3100AO-117712
SystemsX.ch Plant growth in a changing environment
(ISO format)
SHAPIGUZOV, Alexey et al. The PPH1 phosphatase is specifically involved in LHCII dephosphorylation and state transitions in Arabidopsis. In: Proceedings of the National Academy of Sciences, 2010, vol. 107, n° 10, p. 4782-7. doi: 10.1073/pnas.0913810107 https://archive-ouverte.unige.ch/unige:33531

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Deposited on : 2014-01-22

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