Direct probing of the interaction between the signal sequence of nascent preprolactin and the signal recognition particle by specific cross-linking.

Wiedmann, Martin; Kurzchalia, Teymuras V.; Bielka, H; Rapoport, Tom A.

doi:10.1083/jcb.104.2.201

Cited by 119 publications

(55 citation statements)

References 26 publications

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“…Stromal proteins were recovered from lysed etiochloroplasts after various stages of import and subjected to immunoprecipitation (Wiedmann et al, 1987), using an antiserum against pPORA (Schulz et al, 1989). 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.…”

Section: Resultsmentioning

confidence: 99%

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

Reinbothe

Satoh²,

Alcaraz³

et al. 2004

Plant Physiology

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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...

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Section: Resultsmentioning

confidence: 99%

“…Immunoprecipitations were performed according to Wiedmann et al (1987). Aliquots of the resulting immunoprecipitates were extracted with 100% acetone and analyzed either electrophoretically or spectroscopically, as indicated below.…”

Section: Analysis Of Stromal Polypeptidesmentioning

confidence: 99%

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

Reinbothe

Satoh²,

Alcaraz³

et al. 2004

Plant Physiology

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“…Immunoprecipitations with prolactin antibodies were performed as described (Wiedmann et al, 1987a). For immunoprecipitations with SSR antibodies after CMC-cross-linking, the samples were treated with 50 mM Na2 HPO4 pH ~, 9, and 1% SDS at 95°C for 5 rain.…”

Section: Cross Linking Of Nascent Preprolactinmentioning

confidence: 99%

“…Translation of the mRNAs in a wheat germ cell-free system (50 td) was carfled out at 27°C for 10 rain in the presence of 50 nM SRP as described (Wiedmann et al, 1987a). Microsomal membranes, extracted with high salt (K-RM) (10 equivalents), were then added and the incubations continued for 3 rain.…”

Section: Cross Linking Of Nascent Preprolactinmentioning

confidence: 99%

The signal sequence receptor has a second subunit and is part of a translocation complex in the endoplasmic reticulum as probed by bifunctional reagents.

Görlich¹,

Prehn²,

Hartmann³

et al. 1990

The Journal of Cell Biology

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Abstract. Bifunctional cross-linking reagents were used to probe the protein environment in the ER membrane of the signal sequence receptor (SSR), a 34-kD integral membrane glycoprotein (Wiedmann, M., T. V. Kurzchalia, E. Hartmarm, and T. A. Rapoport. 1987. Nature [Lond.]. 328:830-833). The proximity of several polypeptides was demonstrated. A 22-kD glycoprotein was identified tightly bound to the 34-kD SSR even after membrane solubilization. The 34-kD polypeptide, now termed otSSR, and the 22-kD polypeptide, the #SSR, represent a heterodimer. We report on the sequence of the/3SSR, its membrane topology, and on the mechanism of its integration into the membrane. Cross-linking also produced dimers of the a-subunit of the SSR indicating that oligomers of the SSR exist in the ER membrane.Various bifunctional cross-linking reagents were used to study the relation to ER membrane proteins of nascent chains of preprolactin and/3-1actamase at different stages of their translocation through the membrane. The predominant cross-linked products obtained in high yields contained the aSSR, indicating in conjunction with previous results that it is a major membrane protein in the neighborhood of translocating nascent chains of secretory proteins.The results support the existence of a translocon, a translocation complex involving the SSR, which constitutes the specific site of protein translocation across the ER membrane.p ROTEIN transport across the ER membrane can be divided into two phases: (a) an initiation phase that generally involves the function of the signal recognition particle (SRP) and of the docking protein (also called SRP receptor) (Meyer et al., 1982;Gilmore et al., 1982), and (b) the actual membrane transfer of the polypeptide. Little is known about the second process. By photocross-linking a first attempt has been made to probe the molecular environment of a nascent polypeptide chain as it passes through the membrane (Kurzchalia et al., 1986;Krieg et al., 1986; Wiedmann et al., 1987 a, b). Photoreactive chemical groups were incorporated into nascent preprolactin chains by the use of modified lysyl-tRNA, and upon irradiation, gave rise to cross-links with proteins located in close proximity. With the photoreactive groups presentin the signal sequence, an integral glycoprotein of the ER membrane (with a molecular mass of 34 kD) was identified that has been provisionally termed signal sequence receptor (SSR) (Wiedrnarm et al., 1987b). Recent results indicate that various regions of the mature portion of a nascent polypeptide are also in close proximity to the SSR during the course of translocation (Krieg et al., 1989;Wiedmann et al., 1989). Thus, SSR may be part of a translocation complex through which or alongside which the nascent chain is guided across the membrane. However, the function of SSR in translocation requires further study since the cross-linking efficiency was rather low and since cross-linking in general can result in unspecific interactions. Furthermore, all previous experiments were performed w...

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“…WSCP oligomerization was analyzed according to Satoh et al [41]. Immunoprecipitations were performed according to Wiedmann et al [42] using an anti-WSCP antiserum of L. virginicum.…”

Section: Protein Analysesmentioning

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

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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.

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Direct probing of the interaction between the signal sequence of nascent preprolactin and the signal recognition particle by specific cross-linking.

Cited by 119 publications

References 26 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 signal sequence receptor has a second subunit and is part of a translocation complex in the endoplasmic reticulum as probed by bifunctional reagents.

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

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