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  • 1
    ISSN: 1432-1432
    Keywords: Gene evolution ; Seed protein genes ; Legumin ; Vicilin ; Gene family ; Sequence homology ; Intron/exon structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Legumin-like 11S and vicilin-like 7S globulins are the main storage proteins of most angiosperms and gymnosperms. The subunits of the hexameric legumin are synthesized as a precursor comprising a N-terminal acidic α- and a C-terminal basic β-chain. The trimeric vicilin molecule consists of subunits composed of two symmetrical N- and C-terminal structural domains. In a multiple alignment we have compared the N-terminal and C-terminal domains of 11 legumns and seven vicilins of several dicot, monocot, and gymnosperm species. The comparisons using all six possible pairwise combinations reveal that the N-terminal and C-terminal domains of both protein families are similar to each other. These results together with data on the distribution of variable and conserved regions, on the positions of susceptible sites for proteolytic attack, as well as on the published 7S protein tertiary structure suggest that both protein families share a common single-domain ancestor molecule and lead to the hypothesis that a triplication event has occurred during the evolution of a putative legumin/vicilin ancestor gene. Moreover, the comparison of the intron/exon pattern reveals that at least three out of five intron positions are precisely conserved between the genes of both protein families, further supporting the idea of a common evolutionary origin of recent legumin and vicilin encoding genes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Key words: Chitinase  ;  β-1 ; 3-Glucanase ; α-Manno‐sidase ; Nicotiana ; Protein secretion ; Suspension culture ; Vacuolar enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. We have investigated the possibility that vacuolar proteins can be secreted into the medium of cultured cells of Nicotiana tabacum L. Time-course and balance-sheet experiments showed that a large fraction, up to ca. 19%, of vacuolar α-mannosidase (EC 3.2.1.24) and vacuolar class I chitinase (EC 3.2.1.14) in suspension cultures accumulated in the medium within one week after subculturing. This effect was most pronounced in media containing 2,4-dichlorophenoxyacetic acid (2,4-D). Under comparable conditions only a small fraction, 1.8–5.1% of the total protein and ca. 1% of malate dehydrogenase (EC 1.1.1.37), which is localized primarily in the mitochondria and cytoplasm, accumulated in the medium. Pulse-chase experiments showed that newly synthesized vacuolar class I isoforms of chitinase and β-1,3-glucanase (EC 3.2.1.39) were released into the medium. Post-translational processing, but not the release of these proteins, was delayed by the secretion inhibitor brefeldin A. Only forms of the proteins present in the vacuole, i.e. mature chitinase and pro-β-1,3-glucanase and mature β-1,3-glucanase, were chased into the medium of tobacco cell-suspension cultures. Our results provide strong evidence that vacuolar α-mannosidase, chitinase and β-1,3-glucanase can be secreted into the medium. They also suggest that secretion of chitinase and β-1,3-glucanase might be via a novel pathway in which the proteins pass through the vacuolar compartment.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Key words: 2S Globulin ; Narbonin (immunolocalization) ; Seed ; Storage Protein ; Translation (in vitro) ; Vicia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Narbonin is a 2S protein from the globulin fraction of narbon bean (Vicia narbonensis L.) cotyledons. Its amino acid composition and the pattern of its regulated accumulation in developing seeds led to the suggestion that narbonin could be a storage protein. Therefore, it was expected to be present in protein bodies of the storage tissue cells. Comparison of the cDNA-derived amino acid sequence with a directly determined partial N-terminal sequence revealed that the primary translation product of narbonin mRNA lacks a transient N-terminal signal peptide (V.H. Nong et al., 1995, Plant Mol Biol 28: 61–72). Narbonin polypeptides that had been synthesized in a cell-free translation system supplemented with dog pancreas microsomes were not protected against degradation by posttranslationally added proteases (protease protection assay). In accordance with the lack of a signal peptide this indicates that the polypeptide was not cotranslationally sequestered into the microsomes. The protein-body fraction that had been isolated from mature narbon bean cotyledons by a non-aqueous gradient centrifugation procedure was free of narbonin; this was found in the soluble cell fraction. In electron micrographs, narbonin could be localized in the cytoplasm using the immuno gold-labelling technique. Previously, it had already been shown that narbonin is too slowly degraded during narbon bean germination to act as a storage protein. From all these results it has to be concluded that narbonin is a cytoplasmic protein which does not belong to the storage proteins in the restricted sense. Other possible functions are discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-601X
    Keywords: 25.75.+r
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Positively charged pions and protons from collisions of Ne+NaF and Au+Au at 1 GeV/nucleon incident energy were measured near midrapidity. The center-of-mass pion spectra deviate from a Maxwell-Boltzmann distribution. The slope of the high-energy part of the pion spectra varies significantly with the system mass and little with the size of the reaction zone. While the total pion yield rises linearly with the number of participant nucleons, the highenergy component increases more than linearly.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 38 (1998), S. 77-99 
    ISSN: 1573-5028
    Keywords: storage proteins ; intracellular sorting ; secretory pathway ; processing ; deposition ; protein bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants store amino acids for longer periods in the form of specific storage proteins. These are deposited in seeds, in root and shoot tubers, in the wood and bark parenchyma of trees and in other vegetative organs. Storage proteins are protected against uncontrolled premature degradation by several mechanisms. The major one is to deposit the storage proteins into specialized membrane-bounded storage organelles, called protein bodies (PB). In the endosperm cells of maize and rice prolamins are sequestered into PBs which are derived from the endoplasmic reticulum (ER). Globulins, the typical storage proteins of dicotyledonous plants, and prolamins of some cereals are transported from the ER through the Golgi apparatus and then into protein storage vacuoles (PSV) which later become transformed into PBs. Sorting and targeting of storage proteins begins during their biosynthesis on membrane-bound polysomes where an N-terminal signal peptide mediates their segregation into the lumen of the ER. After cleavage of the signal peptide, the polypeptides are glycosylated and folded with the aid of chaperones. While still in the ER, disulfide bridges are formed which stabilize the structure and several polypeptides are joined to form an oligomer which has the proper conformation to be either deposited in ER-derived PB or to be further transferred to the PSV. At the trans-Golgi cisternae transport vesicles are sequestered which carry the storage proteins to the PSV. Several storage proteins are also processed after arriving in the PSVs in order to generate a conformation that is capable of final deposition. Some storage protein precursors have short N- or C-terminal targeting sequences which are detached after arrival in the PSV. Others have been shown to have internal sequence regions which could act as targeting information. In some cases positive targeting information is known to mediate sorting into the PSV whereas in other cases aggregation and membrane association seem to be major sorting mechanisms.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5028
    Keywords: biosynthesis ; gene structure ; narbonin ; recombinant protein ; 2S globulin ; seed storage protein ; Victa narbonensis L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract cDNA and genomic clones encoding narbonin, a 2S globulin from the seed of narbon bean (Vicia narbonensis L.), were obtained using the polymerase chain reaction (PCR) and sequenced. The full-length cDNA as well as genomic clones contain a single open reading frame (ORF) of 873 bp that encodes a protein with 291 amino acids comprising the mature narbonin polypeptide (M r ca. 33 100) and an initiation methionine. The deduced amino acid sequence lacks a transient N-terminal signal peptide. The genomic clones do not contain any intron. No homology was found to nucleic acid and protein sequences so far registered in sequence data libraries. The biosynthesis of narbonin during embryogenesis is developmentally-regulated and its pattern of synthesis closely resembles that of typical seed storage globulins. However, during seed germination narbonin was degraded very slowly, indicating that it may have other function than storage protein. Southern analysis suggests the existence of a small narbonin gene family. Narbonin genes were also found in four different species of the genus Vicia as well as in other legumes such as Canavalia ensiformis and Glycine max. In Escherichia coli a recombinant narbonin was produced which yielded crystals like those prepared from narbonin purified from seeds.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9788
    Keywords: legumin ; methionine ; modification ; nutritional value ; Vicia faba ; vicilin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two different attempts have been undertaken to improve the amino acid composition of storage proteins from field bean (Vicia faba) by genetic engineering. First, legumin was modified to generate a new peptide sequence at the C-terminus containing 4 methionine residues. Second, vicilin was modified by generating 8 single methionine residues distributed over the peptide sequence. The genes were expressed in different systems includingin vitro transcription and translation and stable transformation into tobacco. The modified legumin was found to be unstable when expressed in tobacco seeds. Although specific mRNA was detected on RNA gel blots, no protein could be found by using protein gel blotting and ELISA. Furthermore, a protease preparation able to process the original legumin precursorin vitro degraded the modified legumin precursor. Contrary, the modified vicilin was accumulated in seeds of tobacco transformed with the gene under the control of the seed specific USP promoter. Both the original and the modified vicilin could be detected on protein gel blots at the expected position. Two-dimensional electrophoresis was employed to analyse the expression of original vicilin. Three vicilin-specific products of almost equal size were observed, indicating a slight modification leading to a change of pI. Quantitative determination using competitive ELISA showed that there is no significant difference in accumulation between original and modified vicilin. In both cases, three plants were found with vicilin amounts in the range of 1–3% of total globulin.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9788
    Keywords: Brazil nut protein, grain legumes, leguminB4 promoter ; seed storage protein ; sulphur amino acid deficiency ; transgenic plants ; Vicia narbonensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to evaluate the possibility of enhancing the sulphur amino acids in grain legumes, we have transferred the gene for the methionine-rich 2S albumin from Brazil nut (Bertholletia excelsa) controlled by a seed-specific promoter intoVicia narbonensis. The coding region of the 2S albumin gene that has been completely synthesized was fused to the seed-specific leguminB4 promoter fromVicia faba. Transgenic lines ofV. narbonensis were generated viaAgrobacterium-mediated gene analysis of leaves, stems, roots and seeds of four R0 plants revealed that the expression of the foreign 2S albumin gene occurred in a seed-specific manner and that the foreign protein is present at levels ranging from 1% to 4.8% of total SDS-soluble seed protein. Since the current protocol for transformation ofV. narbonensis has not yet been published, a detailed description of the method is given.
    Type of Medium: Electronic Resource
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