Purification of a Protein Phosphatase from Chloroplast Stroma Capable of Dephosphorylating the Light-Harvesting Complex-II

Hammer, Mark F.; Markwell, John; Sarath, Gautam

doi:10.1104/pp.113.1.227

Cited by 33 publications

(23 citation statements)

References 28 publications

(35 reference statements)

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“…The presence of different phosphatases is one possible explanation for the various kinetic classes that were discerned in assays of endogenous phosphatase activity with isolated thylakoid membranes from pea (Pisum sativum) chloroplasts (Silverstein et al, 1993). The strong preference of PBCP for Mn 2+ and its insensitivity to NaF distinguish it from both the stromal and the membrane phosphatases active on LHCII phosphopeptides, which were previously purified from pea chloroplasts (Hammer et al, 1995(Hammer et al, , 1997. It is expected that further phosphatases involved in regulating thylakoid membrane structure and function remain to be identified.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Photosystem II Phosphatase Involved in Light Acclimation in Arabidopsis

et al. 2012

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Reversible protein phosphorylation plays a major role in the acclimation of the photosynthetic apparatus to changes in light. Two paralogous kinases phosphorylate subsets of thylakoid membrane proteins. STATE TRANSITION7 (STN7) phosphorylates LHCII, the light-harvesting antenna of photosystem II (PSII), to balance the activity of the two photosystems through state transitions. STN8, which is mainly involved in phosphorylation of PSII core subunits, influences folding of the thylakoid membranes and repair of PSII after photodamage. The rapid reversibility of these acclimatory responses requires the action of protein phosphatases. In a reverse genetic screen, we identified the chloroplast PP2C phosphatase, PHOTOSYSTEM II CORE PHOSPHATASE (PBCP), which is required for efficient dephosphorylation of PSII proteins. Its targets, identified by immunoblotting and mass spectrometry, largely coincide with those of the kinase STN8. The recombinant phosphatase is active in vitro on a synthetic substrate or on isolated thylakoids. Thylakoid folding is affected in the absence of PBCP, while its overexpression alters the kinetics of state transitions. PBCP and STN8 form an antagonistic kinase and phosphatase pair whose substrate specificity and physiological functions are distinct from those of STN7 and the counteracting phosphatase PROTEIN PHOSPHATASE1/ THYLAKOID-ASSOCIATED PHOSPHATASE38, but their activities may overlap to some degree.

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Section: Discussionmentioning

confidence: 99%

Identification of a Photosystem II Phosphatase Involved in Light Acclimation in Arabidopsis

et al. 2012

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“…Further work reported that another phosphatase activity, peripherally associated on the thylakoid membrane, can also dephosphorylate thylakoid proteins (Sun et al, 1989). Later on, a 29-kD stromal phosphatase was purified and found to be capable of dephosphorylating LHCII, too (Hammer et al, 1995(Hammer et al, , 1997. The activities of thylakoid protein phosphatases are independent of the redox states, and the kinetics of dephosphorylation reactions are heterogeneous among different substrates, including LHCII and PSII core subunits D1, D2, and CP43 (Silverstein et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

Structural Mechanism Underlying the Specific Recognition between the Arabidopsis State-Transition Phosphatase TAP38/PPH1 and Phosphorylated Light-Harvesting Complex Protein Lhcb1

Wei

Guo

et al. 2015

Plant Cell

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During state transitions, plants regulate energy distribution between photosystems I and II through reversible phosphorylation and lateral migration of the major light-harvesting complex LHCII. Dephosphorylation of LHCII and the transition from state 2 to state 1 requires a thylakoid membrane-associated phosphatase named TAP38 or PPH1. TAP38/PPH1 specifically targets LHCII but not the core subunits of photosystem II, whereas the underlying molecular mechanism of their mutual recognition is currently unclear. Here, we present the structures of Arabidopsis thaliana TAP38/PPH1 in the substrate-free and substrate-bound states. The protein contains a type 2C serine/threonine protein phosphatase (PP2C) core domain, a Mn 2+ (or Mg 2+ ) binuclear center and two additional motifs contributing to substrate recognition. A 15-mer phosphorylated N-terminal peptide of Lhcb1 binds to TAP38/ PPH1 on two surface clefts enclosed by the additional motifs. The first segment of the phosphopeptide is clamped by a pair of tooth-like arginine residues at Cleft 1 site. The binding adopts the lock-and-key mechanism with slight rearrangement of the substrate binding residues on TAP38/PPH1. Meanwhile, a more evident substrate-induced fitting occurs on Cleft 2 harboring the extended part of the phosphopeptide. The results unravel the bases for the specific recognition between TAP38/PPH1 and phosphorylated Lhcb1, a crucial step in state transitions.

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“…Vener et al (10,11) have shown that the activation of the thylakoid protein phosphorylation involves binding of plastoquinol to the Q o site of the cytochrome b/f complex. Both thylakoid-bound (1,12,13) and soluble (14) protein phosphatases, active in dephosphorylation of thylakoid phosphoproteins, are reported to be present in plant chloroplasts.…”

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confidence: 99%

Phosphorylation of Light-harvesting Complex II and Photosystem II Core Proteins Shows Different Irradiance-dependent Regulation in Vivo

Rintamäki

Salonen

Suoranta

et al. 1997

Journal of Biological Chemistry

229

226

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An immunological approach using a polyclonal phosphothreonine antibody is introduced for the analysis of thylakoid protein phosphorylation in vivo. Virtually the same photosystem II (PSII) core phosphoproteins (D1, D2, CP43, and the psbH gene product) and the lightharvesting chlorophyll a/b complex II (LHCII) phosphopolypeptides (LHCB1 and LHCB2), as earlier identified by radiolabeling experiments, were recognized in both pumpkin and spinach leaves. Notably, the PSII core proteins and LHCII polypeptides were found to have a different phosphorylation pattern in vivo with respect to increasing irradiance. Phosphorylation of the PSII core proteins in leaf discs attained the saturation level at the growth light intensity, and this level was also maintained at high irradiances. Maximal phosphorylation of LHCII polypeptides only occurred at low light intensities, far below the growth irradiance, and then drastically decreased at higher irradiances. These observations are at variance with traditional studies in vitro, where LHCII shows a light-dependent increase in phosphorylation, which is maintained even at high irradiances. Only a slow restoration of the phosphorylation capacity for LHCII polypeptides at the low light conditions occurred in vivo after the high light-induced inactivation. Furthermore, if thylakoid membranes were isolated from the high light-inactivated leaves, no restoration of LHCII phosphorylation took place in vitro. However, both the high light-induced inactivation and low light-induced restoration of LHCII phosphorylation seen in vivo could be mimicked in isolated thylakoid membranes by incubating with reduced and oxidized dithiothreitol, respectively. We propose that stromal components are involved in the regulation of LHCII phosphorylation in vivo, and inhibition of LHCII phosphorylation under increasing irradiance results from reduction of the thiol groups in the LHCII kinase. Photosystem (PS)1 II is a multiprotein complex of the thyla- (14) protein phosphatases, active in dephosphorylation of thylakoid phosphoproteins, are reported to be present in plant chloroplasts. Distinct physiological roles have been established for the phosphorylation of LHCII polypeptides, being implicated in the regulation of excitation energy distribution between PSII and PSI (1, 2), and in the protection of PSII against photoinhibition (15,16). Under conditions where PSII becomes more excited than PSI, the redox-controlled kinase is activated and phosphorylates LHCII polypeptides. The outer LHCII subcomplex, consisting of LHCB1 and LHCB2 proteins (see, e.g., Ref. 17), then detaches from the PSII complex and migrates out from the appressed region of the thylakoid membrane, thereby reducing the excitation of PSII (1). Dephosphorylation of this mobile LHCII subcomplex allows its subsequent migration back to the stacked grana region and reassociation with PSII (16).The only function so far established for reversible phosphorylation of PSII core proteins is the regulation of the degradation of photodamaged D1 protein ...

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Purification of a Protein Phosphatase from Chloroplast Stroma Capable of Dephosphorylating the Light-Harvesting Complex-II

Cited by 33 publications

References 28 publications

Identification of a Photosystem II Phosphatase Involved in Light Acclimation in Arabidopsis

Identification of a Photosystem II Phosphatase Involved in Light Acclimation in Arabidopsis

Structural Mechanism Underlying the Specific Recognition between the Arabidopsis State-Transition Phosphatase TAP38/PPH1 and Phosphorylated Light-Harvesting Complex Protein Lhcb1

Phosphorylation of Light-harvesting Complex II and Photosystem II Core Proteins Shows Different Irradiance-dependent Regulation in Vivo

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