101
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Denecke J, Vitale A. The use of protoplasts to study protein synthesis and transport by the plant endomembrane system. Methods Cell Biol 1995; 50:335-48. [PMID: 8531806 DOI: 10.1016/s0091-679x(08)61041-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- J Denecke
- Department of Molecular Genetics, Uppsala Genetic Center, Swedish University of Agricultural Sciences, Sweden
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102
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Runeberg-Roos P, Kervinen J, Kovaleva V, Raikhel NV, Gal S. The aspartic proteinase of barley is a vacuolar enzyme that processes probarley lectin in vitro. PLANT PHYSIOLOGY 1994; 105:321-9. [PMID: 8029356 PMCID: PMC159360 DOI: 10.1104/pp.105.1.321] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Previous work suggested that the aspartic proteinase from Hordeum vulgare (HvAP) would be a vacuolar protein in plant cells. Based on N-terminal sequencing we show that the in vitro-translated protein was translocated into the lumen of microsomal membranes, causing a concomitant removal of 25 amino acid residues from the protein. Vacuoles were purified from barley leaf protoplasts and were shown to contain all of the aspartic proteinase activity found in the protoplasts. This vacuolar localization of HvAP was confirmed with immunocytochemical electron microscopy using antibodies to HvAP in both barley leaf and root cells. In an attempt to discern a function for this protease, we investigated the ability of HvAP to process the C-terminal proregion of barley lectin (BL) in vitro. Prolectin (proBL), expressed in bacteria, was processed rapidly when HvAP was added. Using several means, we were able to determine that 13 amino acid residues at the C terminus of proBL were cleaved off, whereas the N terminus stayed intact during this incubation. Immunohistochemical electron microscopy showed that HvAP and BL are co-localized in the root cells of developing embryos and germinating seedlings. Thus, we propose that the vacuolar HvAP participates in processing the C terminus of BL.
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103
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Kirsch T, Paris N, Butler JM, Beevers L, Rogers JC. Purification and initial characterization of a potential plant vacuolar targeting receptor. Proc Natl Acad Sci U S A 1994; 91:3403-7. [PMID: 8159760 PMCID: PMC43585 DOI: 10.1073/pnas.91.8.3403] [Citation(s) in RCA: 196] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Clathrin-coated vesicles are known to be involved in the transport of proteins from the Golgi to the vacuole in plant cells. The mechanisms by which proteins are directed into this pathway are not known. Here we identify an integral membrane protein of approximately 80 kDa, extracted from clathrin-coated vesicles of developing pea (Pisum sativum L.) cotyledons, that bound at neutral pH to an affinity column prepared with the N-terminal targeting determinant of the vacuolar thiol protease, proaleurain, and eluted when the pH was lowered to 4. The protein was not retained on a control column prepared with the N-terminal sequence of a homologous, secreted thiol protease, endopeptidase B. The 80-kDa protein also accumulated in a membrane fraction that is less dense than clathrin-coated vesicles. In vitro studies demonstrated a binding constant of 37 nM between the approximately 80 kDa protein and the proaleurain targeting determinant. A peptide with a vacuolar targeting determinant from prosporamin weakly competed for binding to the approximately-80 kDa protein, while a peptide carrying a single amino acid substitution known to abolish prosporamin vacuolar targeting had no measurable binding affinity for the protein. The binding protein is a glycoprotein with a transmembrane orientation in which the C terminus is exposed to the cytoplasm. The binding domain is located in the N-terminal luminal portion of the protein. These properties of the binding protein are consistent with the function of a receptor that would select proteins in the trans-Golgi for sorting to clathrin-coated vesicles and delivery to the vacuole.
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Affiliation(s)
- T Kirsch
- Department of Botany and Microbiology, University of Oklahoma, Norman 73019
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104
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Satiat-Jeunemaitre B, Hawes C. G.A.T.T. (A General Agreement on Traffic and Transport) and Brefeldin A in Plant Cells. THE PLANT CELL 1994; 6:463-467. [PMID: 12244244 PMCID: PMC160448 DOI: 10.1105/tpc.6.4.463] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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105
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Gomez L, Chrispeels MJ. Tonoplast and Soluble Vacuolar Proteins Are Targeted by Different Mechanisms. THE PLANT CELL 1993; 5:1113-1124. [PMID: 12271099 PMCID: PMC160345 DOI: 10.1105/tpc.5.9.1113] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The delivery of proteins to the vacuole and its limiting membrane (the tonoplast) by the secretory system is thought to be a dissociative process in which vesicles bud from one compartment and fuse with another. We studied the transport kinetics of phytohemagglutinin (PHA) and tonoplast intrinsic protein (TIP) in mesophyll protoplasts obtained from transgenic tobacco plants transformed with genes encoding these two proteins. In pulse-chase experiments, arrival of PHA in the vacuole was found to be slower (completed 24 hr after synthesis) than the arrival of TIP in the tonoplast (completed 6 hr after synthesis). Brefeldin A and monensin block protein transport by interfering in specific vesicle transport steps. Brefeldin A prevents anterograde vesicle transport between the endoplasmic reticulum and the Golgi, whereas monensin inhibits correct sorting in the trans-Golgi network by disrupting the proton gradient across the membrane. Both inhibitors blocked the transport of PHA to the vacuole and altered the rate at which its complex glycan is processed by Golgi enzymes. Neither drug stopped the arrival of TIP in the tonoplast, suggesting that the flow of vesicles continues in the presence of these inhibitors. We suggest that soluble proteins like PHA and membrane proteins like TIP reach their vacuolar destinations by different paths.
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Affiliation(s)
- L. Gomez
- Department of Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0116
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106
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Abstract
Although many properties of the targeting of plant endomembrane proteins are similar to mammalian and yeast systems, several clear differences are found that will be stressed in this review. In the past year, significant advances in our understanding of storage protein segregation in the endoplasmic reticulum, compartmentation of Golgi, and the signals for vacuolar protein targeting have been made. This work will form the basis for determining the mechanism of these sorting phenomena.
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Affiliation(s)
- S Gal
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing
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107
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D'Hondt K, Van Damme J, Van Den Bossche C, Leejeerajumnean S, De Rycke R, Derksen J, Vandekerckhove J, Krebbers E. Studies of the role of the propeptides of the Arabidopsis thaliana 2S albumin. PLANT PHYSIOLOGY 1993; 102:425-33. [PMID: 8108508 PMCID: PMC158796 DOI: 10.1104/pp.102.2.425] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To investigate the possible roles of the Arabidopsis thaliana 2S albumin propeptides with respect to sorting, processing, and stability of the protein in plant cells, five gene constructions deleting or modifying the propeptides were made based on one of the genes encoding the Arabidopsis 2S albumin. These constructions were introduced into tobacco (Nicotiana tabacum) plants. Using subcellular fractionation and immunocytochemistry on ripe seeds, it was demonstrated that none of the propeptides was necessary for the sorting of the protein. Detailed protein-chemical analysis of the mature gene products indicated that, for all of the modified 2S albumin precursors made, the proteins were stably folded and correctly processed. However, the latter is less efficient when the internal fragment between the small and the large subunit is missing or when this internal fragment is changed. In an attempt to establish a rapid assay system for modified 2S albumin precursors, yeast cells were transformed with the same gene constructs. It was demonstrated that the processing machinery in yeast cells differs from that in plants, and, in a perhaps related observation, differences in stability of a particular modified protein were observed.
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Affiliation(s)
- K D'Hondt
- Plant Genetic Systems, Gent, Belgium
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108
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Dombrowski JE, Schroeder MR, Bednarek SY, Raikhel NV. Determination of the functional elements within the vacuolar targeting signal of barley lectin. THE PLANT CELL 1993; 5:587-96. [PMID: 8518558 PMCID: PMC160296 DOI: 10.1105/tpc.5.5.587] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
We have previously demonstrated that the carboxyl-terminal propeptide of barley lectin is both necessary and sufficient for protein sorting to the plant vacuole. Specific mutations were constructed to determine which amino acid residues or secondary structural determinants of the carboxyl-terminal propeptide affect proper protein sorting. We have found that no consensus sequence or common structural determinants are required for proper sorting of barley lectin to the vacuole. However, our analysis demonstrated the importance of hydrophobic residues in vacuolar targeting. In addition, at least three exposed amino acid residues are necessary for efficient sorting. Sorting was disrupted by the addition of two glycine residues at the carboxyl-terminal end of the targeting signal or by the translocation of the glycan to the carboxy terminus of the propeptide. These results suggest that some components of the sorting apparatus interact with the carboxy terminus of the propeptide.
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Affiliation(s)
- J E Dombrowski
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing 48824-1312
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109
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Schroeder MR, Borkhsenious ON, Matsuoka K, Nakamura K, Raikhel NV. Colocalization of barley lectin and sporamin in vacuoles of transgenic tobacco plants. PLANT PHYSIOLOGY 1993; 101:451-8. [PMID: 8278507 PMCID: PMC160591 DOI: 10.1104/pp.101.2.451] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Various targeting motifs have been identified for plant proteins delivered to the vacuole. For barley (Hordeum vulgare) lectin, a typical Gramineae lectin and defense-related protein, the vacuolar information is contained in a carboxyl-terminal propeptide. In contrast, the vacuolar targeting information of sporamin, a storage protein from the tuberous roots of the sweet potato (Ipomoea batatas), is encoded in an amino-terminal propeptide. Both proteins were expressed simultaneously in transgenic tobacco plants to enable analysis of their posttranslational processing and subcellular localization by pulse-chase labeling and electron-microscopic immunocytochemical methods. The pulse-chase experiments demonstrated that processing and delivery to the vacuole are not impaired by the simultaneous expression of barley lectin and sporamin. Both proteins were targeted quantitatively to the vacuole, indicating that the carboxyl-terminal and amino-terminal propeptides are equally recognized by the vacuolar protein-sorting machinery. Double-labeling experiments showed that barley lectin and sporamin accumulate in the same vacuole of transgenic tobacco (Nicotiana tabacum) leaf and root cells.
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Affiliation(s)
- M R Schroeder
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing 48824-1312
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110
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Melchers LS, Sela-Buurlage MB, Vloemans SA, Woloshuk CP, Van Roekel JS, Pen J, van den Elzen PJ, Cornelissen BJ. Extracellular targeting of the vacuolar tobacco proteins AP24, chitinase and beta-1,3-glucanase in transgenic plants. PLANT MOLECULAR BIOLOGY 1993; 21:583-93. [PMID: 8448358 DOI: 10.1007/bf00014542] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The Nicotiana tabacum ap24 gene encoding a protein with antifungal activity toward Phytophthora infestans has been characterized. Analysis of cDNA clones revealed that at least three ap24-like genes are induced in tobacco upon infection with tobacco mosaic virus. Amino acid sequencing of the purified protein showed that AP24 is synthesized as a preproprotein from which an amino-terminal signal peptide and a carboxyl-terminal propeptide (CTPP) are cleaved off during post-translational processing. The functional role of the CTPP was investigated by expressing chimeric genes encoding either wild-type AP24 or a mutant protein lacking the CTPP. Plants expressing the wild-type construct resulted in proteins properly sorted to the vacuole. In contrast, the proteins produced in plants expressing the mutant construct were secreted extracellularly, indicating that the CTPP is necessary for targeting of AP24 to the vacuoles. Similar results were obtained for vacuolar chitinases and beta-1,3-glucanases of tobacco. The extracellularly targeted mutant proteins were shown to have retained their biological activity. Together, these results suggest that within all vacuolar pathogenesis-related proteins the targeting information resides in a short carboxyl-terminal propeptide which is removed during or after transport to the plant vacuole.
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111
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Linthorst HJ, van der Does C, van Kan JA, Bol JF. Nucleotide sequence of a cDNA clone encoding tomato (Lycopersicon esculentum) cysteine proteinase. PLANT PHYSIOLOGY 1993; 101:705-6. [PMID: 8278519 PMCID: PMC160628 DOI: 10.1104/pp.101.2.705] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- H J Linthorst
- Department of Biochemistry, Leiden University, The Netherlands
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112
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Linthorst HJ, van der Does C, Brederode FT, Bol JF. Circadian expression and induction by wounding of tobacco genes for cysteine proteinase. PLANT MOLECULAR BIOLOGY 1993; 21:685-94. [PMID: 8448366 DOI: 10.1007/bf00014551] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two sets of clones were isolated from a tobacco cDNA library, utilizing as a probe a PCR fragment obtained from tomato cDNA using a degenerate primer based on the sequence of tomato systemin. Contrary to expectation, the clones did not correspond to tobacco homologues of tomato pro-systemin. However, the cDNAs encoded two highly similar proteins with extensive structural homology to cysteine proteinases from a wide range of plant and animal species. Northern blot analyses showed that in unstressed tobacco leaf the genes for the putative proteinases are expressed according to a circadian rhythm. Furthermore, incision wounding enhances the expression approximately six-fold. Other forms of stress, such as infection with tobacco mosaic virus, treatment with ethephon or UV light do not result in induced expression of the tobacco cysteine proteinase genes.
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Affiliation(s)
- H J Linthorst
- Department of Biochemistry, Leiden University, Netherlands
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113
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Rogers JC, Rogers SW. Definition and functional implications of gibberellin and abscisic acid cis-acting hormone response complexes. THE PLANT CELL 1992. [PMID: 1477557 DOI: 10.2307/3869515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The mechanisms by which cis-acting hormone response elements affect transcription is unclear. In this study, we demonstrated that a second "coupling element," identified as O2S, must be present to allow a single copy of either the gibberellin response element (GARE) or the abscisic acid response element (ABRE) to mediate their hormonal effects in the barley Amy32b alpha-amylase gene promoter. The interactive effects of the O2S and the GARE are constrained positionally and spatially; thus, together they form a gibberellin response complex (GARC). The absolute requirement of the O2S for function of the ABRE demonstrates that these together form an abscisic acid response complex (ABRC). A second copy of the GARE can substitute for the O2S in the GARC, but only in one orientation. By expressing the GARC-containing and ABRC-containing promoters in developing aleurone tissue, we showed that hormonal effects prevent alpha-amylase gene expression during the second half of grain development, but other mechanisms suppress expression earlier. Our results suggest that the specific sequence serving as a coupling element in a given gene promoter will greatly affect where and when the GARE or ABRE will be able to regulate transcription.
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Affiliation(s)
- J C Rogers
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
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114
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Rogers JC, Rogers SW. Definition and functional implications of gibberellin and abscisic acid cis-acting hormone response complexes. THE PLANT CELL 1992; 4:1443-51. [PMID: 1477557 PMCID: PMC160231 DOI: 10.1105/tpc.4.11.1443] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The mechanisms by which cis-acting hormone response elements affect transcription is unclear. In this study, we demonstrated that a second "coupling element," identified as O2S, must be present to allow a single copy of either the gibberellin response element (GARE) or the abscisic acid response element (ABRE) to mediate their hormonal effects in the barley Amy32b alpha-amylase gene promoter. The interactive effects of the O2S and the GARE are constrained positionally and spatially; thus, together they form a gibberellin response complex (GARC). The absolute requirement of the O2S for function of the ABRE demonstrates that these together form an abscisic acid response complex (ABRC). A second copy of the GARE can substitute for the O2S in the GARC, but only in one orientation. By expressing the GARC-containing and ABRC-containing promoters in developing aleurone tissue, we showed that hormonal effects prevent alpha-amylase gene expression during the second half of grain development, but other mechanisms suppress expression earlier. Our results suggest that the specific sequence serving as a coupling element in a given gene promoter will greatly affect where and when the GARE or ABRE will be able to regulate transcription.
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Affiliation(s)
- J C Rogers
- Division of Hematology-Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
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