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  • methionine  (2)
  • Gene evolution  (1)
  • Gene transfer  (1)
  • 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: 1617-4623
    Keywords: Gene transfer ; Gene expression ; 2S Brazil nut albumin ; Grain legumes ; Vicia narbonensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coding region of the 2S albumin gene of Brazil nut (Bertholletia excelsa H.B.K.) was completely synthesized, placed under control of the cauliflower mosaic virus (CaMV) 35S promoter and inserted into the binary vector plasmid pGSGLUC1, thus giving rise to pGSGLUC1-2S. This was used for transformation of tobacco (Nicotiana tabacum L. cv. Petit Havanna) and of the grain legume Vicia narbonensis L., mediated by the supervirulent Agrobacterium tumefaciens strain EHA 101. Putative transformants were selected by screening for neomycin phosphotransferase (NPT II) and β-glucuronidase (GUS) activities. Transgenic plants were grown until flowering and fruiting occurred. The presence of the foreign gene was confirmed by Southern analysis. GUS activity was found in all organs of the regenerated transgenic tobacco and legume plants, including the seeds. In the legume, the highest expression levels of the CaMV 35S promoter-controlled 2S albumin gene were observed in leaves and roots. 2S albumin was localized in the vacuoles of leaf mesophyll cells of transgenic tobacco. The Brazil nut protein was present in the 2S fraction after gel filtration chromatography of the legume seed proteins and could be clearly identified by immunoblotting. Analysis of seeds from the R2 progenies of the legume and of transgenic tobacco plants revealed Mendelian inheritance of the foreign gene. Agrobacterium rhizogenes strain RifR 15834 harbouring the binary vector pGSGLUCl2S was also used to transform Pisum sativum L. and Vicia faba L. Hairy roots expressed the 2S albumin-specific gene. Several shoots were raised but they never completely rooted and no fertile plants were obtained from these transformants.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5060
    Keywords: Vicia narbonensis ; gene transfer ; gene expression ; seeds ; 2S albumin ; methionine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Epicotyl explants were co-cultivated with Agrobacterium tumefaciens EHA101 to transfer a chimeric 2S albumin gene construct carried in the binary Ti plasmid vectors pGSGLUC1 or pGA472 into the grain legume Vicia narbonensis. This gene encoding the sulphur-rich Brazil nut albumin was under the control of either the CaMV 35S promoter which permits gene expression in all organs, or the Vicia faba legumin B4 promoter which elicits seed-specific gene expression. After callus formation and selection for kanamycin resistance, somatic embryos were induced which, in the case of transformation with the vector pGSGLUC1, were screened for GUS activity. Embryos that produced GUS were in addition analysed for 2S albumin formation. Selected transgenic embryos were cloned by multiple shoot regeneration. Rooted and fertile plants were obtained by grafting transgenic shoots on the appropriate seedlings. R1 and R2 generations were raised and analysed for GUS as well as 2S albumin gene expression. Expression of the 35S promoter/2S albumin gene fusion took place in all organs of the transgenic plants including the cotyledons of seeds, whereas seed-specific gene expression was found in transformants with the legumin promoter/2S albumin gene fusion. The 2S albumin accumulated in the 2S protein fraction of transgenic seeds and its primary translation product was processed into the 9 and 3 kDa polypeptide chains. The foreign protein was localised in the protein bodies of the grain legume. Analysis of the R2 plants indicated Mendelian inheritance of the 2S albumin gene. In homozygous V. narbonensis plants the amounts of 2S albumin were twice that present in the corresponding heterozygous plants. Whereas only low level formation of the foreign protein was achieved if the gene was under the control of the 35S promoter, approximately 3.0% of the soluble seed protein was 2S albumin if seed-specific gene expression was directed by the legumin B4 promoter. Some of these transformants exhibited a three-fold increase in the methionine content of the salt-soluble protein fraction extracted from seeds.
    Type of Medium: Electronic Resource
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  • 4
    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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