Phosphorylated Photosystem I Antenna Proteins in Barley

Knoetzel, Jürgen; Meyer, Doris; Grimme, L. Horst

doi:10.1007/978-94-009-0173-5_28

Cited by 6 publications

(5 citation statements)

References 7 publications

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“…32 P labeling of plant material followed by gel electrophoresis and autoradiography did not prove phosphorylation of LHCI proteins under conditions in which the various PSII proteins are phosphorylated (41,42). These results are in contrast to an immunoblot study performed with antiphosphothreonine and anti-phosphoserine antibodies (36). Both antibodies cross reacted with all Lhca proteins that were tested (Lhca1-4), indicating phosphorylation at various sites in all proteins.…”

Section: Lhci Heterogeneity In Higher Plantsmentioning

confidence: 56%

“…Peptides identifying Lhca2 could be detected in spots C-E only after the amount of protein loaded on the gels and the trypsin concentration used for digestion were increased (see Experimental Procedures). One possible explanation for the different electrophoretic forms of each Lhca protein could be that the proteins are phosphorylated to different degrees as suggested from a study with barley and antibodies that recognize phosphorylated proteins (36). To examine phosphorylation of Lhca proteins in tomato, proteins of PSI and thylakoids were separated in a 1-D gel.…”

Section: Resultsmentioning

confidence: 99%

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Proteomic Analysis of the Photosystem I Light-Harvesting Antenna in Tomato (Lycopersicon esculentum)

et al. 2004

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Until now, more genes of the light-harvesting antenna of higher-plant photosystem I (PSI) than proteins have been described. To improve our understanding of the composition of light-harvesting complex I (LHCI) of tomato (Lycopersicon esculentum), we combined one- and two-dimensional (1-D and 2-D, respectively) gel electrophoresis with immunoblotting and tandem mass spectrometry (MS/MS). Separation of PSI with high-resolution 1-D gels allowed separation of five bands attributed to proteins of LHCI. Immunoblotting with monospecific antibodies and MS/MS analysis enabled the correct assignment of the four prominent bands to light-harvesting proteins Lhca1-4. The fifth band was recognized by only the Lhca1 antibody. Immunodetection as well as mass spectrometric analysis revealed that these protein bands contain not only the eponymous protein but also other Lhca proteins, indicating a heterogeneous protein composition of Lhca bands. Additionally, highly sensitive MS/MS allowed detection of a second Lhca4 isoform and of Lhca5. These proteins had not been described before on the protein level in higher plants. Two-dimensional gel electrophoresis revealed an even more diverse composition of individual Lhca proteins than was apparent from 1-D gels. For each of the four prominent Lhca proteins, four to five isoforms with different isoelectric points could be identified. In the case of Lhca1, Lhca4, and Lhca3, additional isoforms with slightly differing molecular masses were identified. Thus, we were able to detect four to ten isoforms of each individual Lhca protein in PSI. Reasons for the origin of Lhca heterogeneity are discussed. The observed variety of Lhca proteins and their isoforms is of particular interest in the context of the recently published crystal structure of photosystem I from pea, which showed the presence of only four Lhca proteins per photosystem I. These findings indicate that several populations of photosystem I that differ in their Lhca composition may exist.

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Section: Lhci Heterogeneity In Higher Plantsmentioning

confidence: 56%

Section: Resultsmentioning

confidence: 99%

Proteomic Analysis of the Photosystem I Light-Harvesting Antenna in Tomato (Lycopersicon esculentum)

et al. 2004

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“…The fourth green gradient band contained a rather pure PSI-LHCI complex which was not labelled. This is interesting in the light of recent reports of LHCI phosphoproteins [22]. The gradient fractions 1 and 2 were pooled and subjected to preparative IEF for the isolation of CP34 according to [8] (results not shown).…”

Section: Isolation Of the Phospho-cp29 From 33p-treated Plantsmentioning

confidence: 95%

A CK2 site is reversibly phosphorylated in the photosystem II subunit CP29

et al. 1996

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Protein phosphorylation is a major mechanism in the regulation of protein function. In chloroplast thylakoids several photosystem II subunits, including the major antenna lightharvesting complex II and several core complex components, are reversibly phosphorylated depending on the redox state of the electron carriers. A previously unknown reversible phosphorylation event has recently been described on the CP29 subunit which leads to conformationai changes and protection from cold stress (Bergantino, E., Dainese, P., Cerovic, Z. Sechi, S. and Bassi, R. (1995) J. Biol Chem. 270, 8474-8481). In this study, we have identified the phosphorylation site on the N-terminal, stromaexposed domain, showing that it is located in a sequence not homologous to the other members of the Lhc family. The phosphorylated sequence is unique in chloroplast membranes since it meets the requirements for CK2 (casein kinase II) kinases. The possibility that this phosphorylation is involved in a signal transdnction pathway is discussed. 1, IntroductionIn the chloroplast, phosphorylation of membrane proteins i. responsible for many of the physiological responses to hanges in incident light and redox poise. The major substrate iavolved in this regulative process is the light-harvesting comllex of photosystem II (LHCII). When PSII is overexcited with respect to PSI, the plastoquinone pool becomes reduced i,nd thus activates a kinase bound to the cytochrome b6/f t omplex [l,2]. This process results in phosphorylation of the Jaajor trimeric LHCII complex in an N-terminal, stroma-exl,osed site [3] leading to the monomerisation of LHCII, dis-, onnection from PSII RC [2,4] and migration of LHCII ~aonomeric subpopulations from grana to stroma membranes t 2,5,6] where they can transfer excitation energy to PSI [5] and bus oxidise the plastoquinone pool. This process can there~ore be understood in terms of regulation of photosystem ntenna size by the transfer of LHCII units away from the Corresponding author. Fax: (39) 45-8098929. ~-mail: bassi@biotech.univr.it tbbreviations. BBY, PSII membrane preparation; CK2, casein kinase !; Chl, chlorophyll; CP, chlorophyll-protein; DM, dodecyl-maltoside; EDTA, ethylenediaminetetraacetic acid; ELFE, electroendoosmotic ~'lectrophoresis; HEPES, N-2-(hydroxy-ethyl)piperazine-N'-2-ethane~ulfonic acid; IEF, isoelectrofocusing; LHCII, light-harvesting complex of PSII; PAGE, polyacrylamide gel electrophoresis; PS, photosystem; rCP29, recombinant CP29 reconstituted from the apoprotein derivatives overproduced in bacteria; RC, reaction centre; ~;DS, sodium dodecyl sulphate; Tris, 2-amino-2-(hydroxymethyl)-l,3-l~ropanediol overexcited photosystem [2]. The underlying mechanism is a conformational change of the LHCII N-terminal portion which undocks this subunit from PSII and increases its affinity for PSI [2].More recently, it was reported that photoinhibitory conditions induce reversible phosphorylation of CP29, another PSII subunit PSI [7]. Although there is strong homology between CP29 and LHCII and both protei...

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“…Recently it was reported that LHCI chlorophyll a/b binding proteins of PS I from barley thylakoid membranes are phosphorylated at threonine and serine residues (Knoetzel et al, 1995). This phosphorylation occurs on the amino-terminal surface exposed segment.…”

Section: Phosphorylation-dependent Reversible Association Of Lhcii With Ps IImentioning

confidence: 99%

State Transition and Photoinhibition

Keren

Ohad

The Molecular Biology of Chloroplasts and Mitochondria in Chlamydomonas

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protein. Excessive excitation induces a stepwise inactivation of PS II, affecting primarily its acceptor side components, thereby promoting charge recombination and oxidative damage. Infrequent excitation of PS II ('low light'), promotes charge recombination driven by the equilibrium between the oxidized states of the PS II donor side manganese cluster and the reduced semiquinone acceptorIn this process are regenerated and their recombination results in oxidative damage exposing the PS II proteins to proteolytic cleavage. De novo protein synthesis and reassembly of PS II compensate for photoinactivation and degradation of the D1 protein. This process involves dissociation of the residual PS II core proteins from the antenna complex, lateral migration from the appressed to the non-appressed lamellae and reassembly with precursor pD1 protein, newly synthesized by polyribosomes bound to non-appressed lamellae. Processing of pD1, light dependent reactivation of the donor side Mn cluster, lateral migration of the reactivated PS II core to the appressed lamellae, and its reassociation with LHCII regenerates active PS II units and complete the PS II photoinactivation and repair cycle. Thus, photoinactivation and repair of PS II activity are regulated at the metabolic and molecular levels and are modulated by environmental changes.

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Phosphorylated Photosystem I Antenna Proteins in Barley

Cited by 6 publications

References 7 publications

Proteomic Analysis of the Photosystem I Light-Harvesting Antenna in Tomato (Lycopersicon esculentum)

Proteomic Analysis of the Photosystem I Light-Harvesting Antenna in Tomato (Lycopersicon esculentum)

A CK2 site is reversibly phosphorylated in the photosystem II subunit CP29

State Transition and Photoinhibition

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