Accumulation, assembly, and digestibility of amarantin expressed in transgenic tropical maize.
An amaranth ( Amaranthus hypochondriacus) 11S globulin cDNA, encoding one of the most important storage proteins (amarantin) of the seed, with a high content of essential amino acids, was used in the transformation of CIMMYT tropical maize genotype. Constructs contained the amarantin cDNA under the control of a tissue-specific promoter from rice glutelin-1 ( osGT1) or a constitutive ( CaMV 35S) promoter with and without the first maize alcohol dehydrogenase intron ( AdH). Southern-blot analysis confirmed the integration of the amarantin cDNA, and copy number ranged from one to more than ten copies per maize genome. Western-blot and ultracentrifugation analyses of transgenic maize indicate that the expressed recombinant amarantin precursors were processed into the mature form, and accumulated stably in maize endosperm. Total protein and some essential amino acids of the best expressing maize augmented 32% and 8-44%, respectively, compared to non-transformed samples. The soluble expressed proteins were susceptible to digestion by simulated gastric and intestinal fluids, and it is suggested that they show no allergenic activity. These findings demonstrate the feasibility of using genetic engineering to improve the amino acid composition of grain crops.
Rascón-Cruz
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Depto. de Biotecnología y Bioquímica, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. Postal 629, 36500, Irapuato, Gto., México.
Sinagawa-García
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Osuna-Castro
J A
JA
Bohorova
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N
Paredes-López
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O
D000426:Alcohol Dehydrogenase / Q000235:genetics; D027721:Amaranthus / Q000737:chemistry; D015139:Blotting, Southern; D018076:DNA, Complementary / Q000235:genetics; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D005818:Genetic Engineering / Q000592:standards; D005983:Glutens / Q000235:genetics; D007438:Introns / Q000235:genetics; D012275:Oryza / Q000737:chemistry / Q000235:genetics*; D037121:Plant Lectins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000737:chemistry; D054788:Ribosome Inactivating Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D014170:Transformation, Genetic; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*
D018076:DNA, Complementary; D037121:Plant Lectins; D054789:Ribosome Inactivating Proteins, Type 1; C061152:amaranthin protein, Amaranthus; D005983:Glutens; D000426:Alcohol Dehydrogenase; D054788:Ribosome Inactivating Proteins