Characterization of Mutants with Alterations of the Phosphorylation Site in the D2 Photosystem II Polypeptide of<i>Chlamydomonas reinhardtii</i>1

Fleischmann, Mark; Rochaix, Jean‐David

doi:10.1104/pp.119.4.1557

Cited by 21 publications

(19 citation statements)

References 44 publications

(62 reference statements)

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“…Previous studies based on the sitedirected mutagenesis of the D2 protein in Chlamydomonas produced contradictory conclusions on the possible phosphorylation of this protein in Chlamydomonas (31,32). In our study, however, we unambiguously determined that D2 underwent phosphorylation at the amino-terminal threonine when Chlamydomonas cells were exposed to reducing conditions (State 2) or light.…”

Section: Figsupporting

confidence: 44%

“…None of these techniques is ideal, and the identification of protein phosphorylation events largely depends on the detection method used (28). For instance, site-directed mutagenesis of the amino-terminal threonine in the Chlamydomonas D2 protein combined with radioactive labeling led one research group to conclude that this threonine was a unique phosphorylation site in this polypeptide (32), whereas other similar work suggested that existence of D2 phosphorylation in C. reinhardtii was still in question (31). The decisive evidence for existence of phosphorylation is provided by the identification of a phosphorylated residue(s) in the sequence of a given protein.…”

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confidence: 99%

“…To date, protein phosphorylation in photosynthetic membranes of plants and algae has been studied by seven different techniques: (i) radioactive labeling (4,6,8,9,24,25), (ii) detection of the shift in the electrophoretic mobility of individual proteins (24, 26 -28), (iii) immunological analyses with anti-phosphoamino acid antibodies (27)(28)(29)(30), (iv) site-directed mutagenesis of potential protein phosphorylation sites (31)(32)(33), (v) mass spectrometric determination of the masses for intact phosphorylated proteins (34,35), (vi) amino-terminal protein sequencing by Edman degradation (36,37), and (vii) identification and mass spectrometric sequencing of phosphorylated peptides obtained by proteolytic treatment of the membranes (38 -41). None of these techniques is ideal, and the identification of protein phosphorylation events largely depends on the detection method used (28).…”

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confidence: 99%

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Environmentally Modulated Phosphoproteome of Photosynthetic Membranes in the Green Alga Chlamydomonas reinhardtii

Turkina

Kargul

Blanco-Rivero

et al. 2006

Molecular & Cellular Proteomics

107

119

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Mapping of in vivoThe thylakoid membranes in chloroplasts of plants and green algae carry out oxygenic photosynthesis. Two multisubunit pigment-containing protein complexes, photosystem II (PSII) 1 and photosystem I (PSI), located in this membrane system work in series to generate an electrochemical potential gradient of protons across the membrane following vectorial electron flow from PSII to PSI via the cytochrome b 6 f complex. PSII uses light to oxidize water, whereas PSI, via a second photoact, uses reducing equivalents derived from PSII to reduce NADP ϩ to NADPH. The electrochemical potential gradient of protons is used to power conversion of ADP to ATP (1). Several thylakoid membrane proteins that make up the PSII complex and its LHCII (light-harvesting chlorophyll a/b-binding proteins of PSII) antennae undergo light-and redox-dependent phosphorylation (2, 3) as discovered more than 2 decades ago (4 -6). Phosphorylation of LHCII in plants and algae controls photosynthetic state transitions, which optimize efficient use of the absorbed light energy by both photosystems. Thus, in State 1 more energy is transferred to PSII, whereas in State 2 a proportion of the excitation energy is redistributed to PSI (7-9). The essential role of protein phosphorylation in state transitions has recently been proven in the studies using mutants of Arabidopsis thaliana plants and the green alga Chlamydomonas reinhardtii deficient in protein kinases STN7 (9) and Stt7 (8), respectively. However, despite the generally assumed similarity in thylakoid protein phosphorylation between plants and algae and a high homology between the plant STN7 and the algal Stt7 protein kinases (8), the extent of photosynthetic state transitions differs between these species. In plant thylakoids, only 15-20% of LHCII participates in the lateral migration between the photosystems, whereas up to 80% of the excitation energy absorbed by the LHCII antenna can be redistributed from PSII to PSI in green alga (8 -10).

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confidence: 44%

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Environmentally Modulated Phosphoproteome of Photosynthetic Membranes in the Green Alga Chlamydomonas reinhardtii

Turkina

Kargul

Blanco-Rivero

et al. 2006

Molecular & Cellular Proteomics

107

119

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“…In C. reinhardtii, a mutation of PsbH that prevents phosphorylation of Thr-2 by replacing it with Ala had no apparent phenotypic consequence (O'Connor et al, 1998). Mutation of the D2 subunit changing Thr-2 to Ala allowed normal photosynthetic activity, but mutations to Asp or Glu, which mimic phosphorylation, strongly affected PSII accumulation (Fleischmann and Rochaix, 1999).…”

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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“…Although it is controversial (Andronis et al, 1998, Fleischmann and Rochaix, 1999, Bonardi et al, 2005, PSII core subunit phosphorylation has been suggested to act as a protection mechanism from proteolytic degradation of photodamaged PSII complex under high-light conditions (Koivuniemi et al, 1995;Kruse et al, 1997;Turkina et al, 2006). Since cells were grown in low light in this study (20 mmol photons m 22 s 21 ), the core subunits are not under the high-light stress.…”

Section: (3) Psii Core Subunits (Cp43 and D2 Protein)mentioning

confidence: 99%

Molecular Remodeling of Photosystem II during State Transitions inChlamydomonas reinhardtii

2008

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State transitions, or the redistribution of light-harvesting complex II (LHCII) proteins between photosystem I (PSI) and photosystem II (PSII), balance the light-harvesting capacity of the two photosystems to optimize the efficiency of photosynthesis. Studies on the migration of LHCII proteins have focused primarily on their reassociation with PSI, but the molecular details on their dissociation from PSII have not been clear. Here, we compare the polypeptide composition, supramolecular organization, and phosphorylation of PSII complexes under PSI-and PSII-favoring conditions (State 1 and State 2, respectively). Three PSII fractions, a PSII core complex, a PSII supercomplex, and a multimer of PSII supercomplex or PSII megacomplex, were obtained from a transformant of the green alga Chlamydomonas reinhardtii carrying a Histagged CP47. Gel filtration and single particles on electron micrographs showed that the megacomplex was predominant in State 1, whereas the core complex was predominant in State 2, indicating that LHCIIs are dissociated from PSII upon state transition. Moreover, in State 2, strongly phosphorylated LHCII type I was found in the supercomplex but not in the megacomplex. Phosphorylated minor LHCIIs (CP26 and CP29) were found only in the unbound form. The PSII subunits were most phosphorylated in the core complex. Based on these observations, we propose a model for PSII remodeling during state transitions, which involves division of the megacomplex into supercomplexes, triggered by phosphorylation of LHCII type I, followed by LHCII undocking from the supercomplex, triggered by phosphorylation of minor LHCIIs and PSII core subunits.

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Characterization of Mutants with Alterations of the Phosphorylation Site in the D2 Photosystem II Polypeptide ofChlamydomonas reinhardtii1

Cited by 21 publications

References 44 publications

Environmentally Modulated Phosphoproteome of Photosynthetic Membranes in the Green Alga Chlamydomonas reinhardtii

Environmentally Modulated Phosphoproteome of Photosynthetic Membranes in the Green Alga Chlamydomonas reinhardtii

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

Molecular Remodeling of Photosystem II during State Transitions inChlamydomonas reinhardtii

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