A Light-Induced Protease from Barley Plastids Degrades NADPH:Protochlorophyllide Oxidoreductase Complexed with Chlorophyllide

Reinbothe, Christiane; Apel, Klaus; Reinbothe, Steffen

doi:10.1128/mcb.15.11.6206

Cited by 65 publications

(46 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We assumed that nascent PORA-Pchlide-NADPH complexes formed upon import may reduce their Pchlide to Chlide and in turn would be degraded if the samples were illuminated. As shown previously, there is a light-induced, ATP-and metal ion-dependent, multicomponent stromal protease that degrades freshly formed POR-product complexes (C. Reinbothe et al, 1995;S. Reinbothe et al, 1995a).…”

Section: Resultsmentioning

confidence: 99%

“…Reinbothe et al, 1995a). This so-called POR-degrading protease is unable to attack PORPchlide-NADPH complexes in darkness (C. Reinbothe et al, 1995;S. Reinbothe et al, 1995a).…”

Section: Resultsmentioning

confidence: 99%

“…Upon illumination, it catalyzes the conversion of Pchlide to Chlide (Boardman, 1962) and in turn rapidly disintegrates (Kahn, 1968). In vivo and in vitro analyses showed that after this reaction has been performed, either POR protein are degraded or Chlide released (C. Reinbothe et al, 1995;S. Reinbothe et al, 1995c).…”

mentioning

confidence: 99%

See 2 more Smart Citations

A Novel Role of Water-Soluble Chlorophyll Proteins in the Transitory Storage of Chorophyllide

Reinbothe

Satoh²,

Alcaraz³

et al. 2004

Plant Physiology

View full text Add to dashboard Cite

All chlorophyll (Chl)-binding proteins involved in photosynthesis of higher plants are hydrophobic membrane proteins integrated into the thylakoids. However, a different category of Chl-binding proteins, the so-called water-soluble Chl proteins (WSCPs), was found in members of the Brassicaceae, Polygonaceae, Chenopodiaceae, and Amaranthaceae families. WSCPs from different plant species bind Chl a and Chl b in different ratios. Some members of the WSCP family are induced after drought and heat stress as well as leaf detachment. It has been proposed that this group of proteins might have a physiological function in the Chl degradation pathway. We demonstrate here that a protein that shared sequence homology to WSCPs accumulated in etiolated barley (Hordeum vulgare) seedlings exposed to light for 2 h. The novel 22-kD protein was attached to the outer envelope of barley etiochloroplasts, and import of the 27-kD precursor was light dependent and induced after feeding the isolated plastids the tetrapyrrole precursor 5-aminolevulinic acid. HPLC analyses and spectroscopic pigment measurements of acetone-extracted pigments showed that the 22-kD protein is complexed with chlorophyllide. We propose a novel role of WSCPs as pigment carriers operating during light-induced chloroplast development.In light-grown seedlings and mature green plants, chlorophyll (Chl) a and Chl b as well as carotenoids are bound to various proteins within PSI and PSII (Ort and Yocum, 1996). These proteins differ in their Chlbinding properties: one group binds only Chl a, whereas the other can bind both Chl a and Chl b (for reviews, see von Wettstein et al., 1995;Green and Durnford, 1996). The first group is represented by the plastid-encoded pigment-binding proteins of the actual reaction centers (PSI-A/B and D1/D2 in PSII) and the photosynthetic cores of PSII (CP43 and CP47).The second group comprises the light-harvesting Chl a/b-binding proteins LHCI and LHCII of PSI and PSII, respectively (Dreyfuss and Thornber, 1994;Kü hlbrandt et al., 1994;Green and Durnford, 1996). These nuclear gene products form the outer antenna complexes of the two photosystems. The Chl content of LHCII accounts for approximately 50% of all Chls in the thylakoid membranes (Kü hlbrandt et al., 1994). LHCII operates as a trimer (Dreyfuss and Thornber, 1994), and each monomer contains Chl a plus Chl b in a 7:6 stoichiometry (Kü hlbrandt et al., 1994). Monomeric LHCII is embedded into the thylakoids via three a-helices (Kü hlbrandt et al., 1994). Similar, structurally related a-helices also occur in other Chl-binding proteins, such as the minor light-harvesting Chl a/bbinding proteins CP29, CP26, CP24, and CP14 (summarized in Green et al., 1991;Jansson, 1994; Paulsen, 1995), and the early light-inducible proteins (ELIPs; Kloppstech et al., 1984;Grimm and Kloppstech, 1987;Grimm et al., 1989; for review, see Adamska, 1997). The S-subunit of PSII (PsbS) is a related but four-helix Chl-binding protein, which contains an additional fourth helix similar to helix 2 present in LHC...

show abstract

Section: Resultsmentioning

confidence: 99%

“…Reinbothe et al, 1995a). This so-called POR-degrading protease is unable to attack PORPchlide-NADPH complexes in darkness (C. Reinbothe et al, 1995;S. Reinbothe et al, 1995a).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Role of Water-Soluble Chlorophyll Proteins in the Transitory Storage of Chorophyllide

Reinbothe

Satoh²,

Alcaraz³

et al. 2004

Plant Physiology

View full text Add to dashboard Cite

show abstract

“…After a 15-min incubation in the dark, the assays were terminated by the addition of 1 l of a mixture containing 10 g ml Ϫ1 antipain and 1 g ml Ϫ1 pepstatin, which efficiently block the POR-degrading stromal protease (39).…”

Section: Reconstitution Of Por-pigment Complexes-[mentioning

confidence: 99%

The Extra Loop Distinguishing POR from the Structurally Related Short-chain Alcohol Dehydrogenases Is Dispensable for Pigment Binding but Needed for the Assembly of Light-harvesting POR-Protochlorophyllide Complex

Reinbothe

Lepinat

Deckers³

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

We have recently discovered a protochlorophyllide (Pchlide)-based light-harvesting complex involved in chlorophyll a biosynthesis. This complex consists of the two previously identified NADPH:protochlorophyllide oxidoreductases (PORs), PORA and PORB, their natural substrates (Pchlide b and Pchlide a, respectively), plus NADPH. These are all held together in a stoichiometry of five PORA-Pchlide b-NADPH complexes and one PORB-Pchlide a-NADPH complex in the prolamellar body of etioplasts. The assembly of this novel light-harvesting POR-Pchlide complex (LHPP) requires both the proper interaction of the PORA and PORB with their cognate substrates as well as the oligomerization of the resulting POR-pigment-NADPH ternary complexes into the native, lipid-containing structure of the etioplast. In this study, we demonstrate that the conserved extra sequence that distinguishes PORA and PORB from the structurally related short-chain alcohol dehydrogenases, is dispensable for pigment binding but needed for the assembly of LHPP. As shown by in vitro mutagenesis, deleting this extra sequence gave rise to assemblyincompetent but pigment-containing PORA and PORB polypeptides.Photosynthesis supports our life on Earth. During photosynthesis, plants collect sunlight and convert this into chemical energy to be conserved in ATP and NADPH (1). A key role in the processes of light absorption and energy transduction is played by the light-harvesting complexes, in particular two light-harvesting chlorophyll a/b-protein complexes termed LHCI 1 and LHCII (2). LHCII is a trimer (3) that operates as the basic antenna to provide the reaction center of photosystem II with excitation energy (4). LHCII is conserved in all green plants (5). Monomeric LHCII consists of 232 amino acids that form three ␣-helices embedded into the thylakoid membrane of the chloroplast (6), the site of photosynthesis. Twelve chlorophylls (Chls) (seven Chl a and five Chl b molecules) and two carotenoids (luteins) are bound per LHCII molecule (6). In the center of the complex, Chl b is in close contact with Chl a for rapid energy transfer and with the carotenoids that prevent the formation of toxic singlet oxygen (6). Energy transfer from Chl b to the closely related Chl a (both compounds differ only in a formyl group instead of a methyl group at the 7-position in the chlorin ring of Chl a) (for a review, see Ref. 7) can take place because of the different energy contents and decay times of their excited states (8, 9). Energy absorbed by Chl b is transferred to Chl a within less than 1 ps, where it remains for 1-3 ns, as shown by the Chl a fluorescence decay time in the purified, detergentsolubilized complex (10).A similar principle of energy transfer has been proposed for the prolamellar body of etioplasts (11). Prolamellar bodies are paracrystalline structures that are present in etiolated plants (12). They contain the immediate Chl precursors protochlorophyllide (Pchlide) a and Pchlide b, respectively, which are differentially bound to two forms of the photoenzyme NA...

show abstract

“…As a result, PORA would be destabilized and turned over. As shown previously, PORA complexed with Chlide is rapidly degraded by a light-, ATP-and metal ion-dependent stromal protease [50,51].…”

Section: Light-induced Disintegration Of Lhpp During Natural Greeningmentioning

confidence: 99%

LHPP, the light-harvesting NADPH:protochlorophyllide (Pchlide) oxidoreductase:Pchlide complex of etiolated plants, is developmentally expressed across the barley leaf gradient

et al. 2004

View full text Add to dashboard Cite

NADPH:protochlorophyllide oxidoreductase is a key enzyme for the light-induced greening of etiolated angiosperm plants. In barley, two POR proteins exist termed PORA and PORB that have previously been proposed to stmcturally and functionally cooperate in terms of a higher molecular mass light-harvesting complex named LHPP, in the prolamellar body of etioplasts [Nature 397 (1999) 80]. In this study we examined the expression pattern of LHPP during seedling etiolation and de-etiolation under different experimental conditions. Our results show that LHPP is developmentally expressed across the barley leaf gradient. We further provide evidence that LHPP operates both in plants that etiolate completely before being exposed to white light and in plants that etiolate only partially and begin light-harvesting as soon as traces of light become available in the uppermost parts of the soil. As a result of light absorption, in either case LHPP converts Pchlide a to chlorophyllide (Chlide) a and in turn disintegrates. The released Chlide a, as well as Chlide b produced upon LHPP's light-dependent dissociation, which leads to the activation of the PORA as a Pchlide £-reducing enzyme, then bind to homologs of water-soluble chlorophyll proteins of Brassicaceae. We propose that these proteins transfer Chlide a and Chlide b\o the thylakoids, where their esterification with phytol and assembly into the photosynthetic membrane complexes ultimately takes place. Presumably due to the tight coupling of LHPP synthesis and degradation, as well as WSCP formation and photosynthetic membrane assembly, eflficient photo-protection is conferred onto the plant.

show abstract

A Light-Induced Protease from Barley Plastids Degrades NADPH:Protochlorophyllide Oxidoreductase Complexed with Chlorophyllide

Cited by 65 publications

References 54 publications

A Novel Role of Water-Soluble Chlorophyll Proteins in the Transitory Storage of Chorophyllide

A Novel Role of Water-Soluble Chlorophyll Proteins in the Transitory Storage of Chorophyllide

The Extra Loop Distinguishing POR from the Structurally Related Short-chain Alcohol Dehydrogenases Is Dispensable for Pigment Binding but Needed for the Assembly of Light-harvesting POR-Protochlorophyllide Complex

LHPP, the light-harvesting NADPH:protochlorophyllide (Pchlide) oxidoreductase:Pchlide complex of etiolated plants, is developmentally expressed across the barley leaf gradient

Contact Info

Product

Resources

About