Changes in the zein composition of protein bodies during maize endosperm development.

Lending, Craig R.; Larkins, Brian A.

doi:10.1105/tpc.1.10.1011

Cited by 295 publications

(201 citation statements)

References 11 publications

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“…Protein body biogenesis in corn endosperm is not well understood. However, analysis of the accumulation pattern of the different zeins in the protein bodies in corn endosperm has led to the theory that the synthesis of these protein bodies is a result of interaction among the different zeins (Lending and Larkins, 1989). The formation of distinct protein bodies with just the 15-kD zein in nonseed tissues is consistent with the "self-assembly" hypothesis and further suggests that intramolecular interaction is sufficient for the biogenesis of these ER-derived protein bodies.…”

Section: Discussionsupporting

confidence: 55%

Accumulation of 15-Kilodalton Zein in Novel Protein Bodies in Transgenic Tobacco

et al. 1995

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Zeins, the seed storage proteins of maize, are a group of alcoholsoluble polypeptides of different molecular masses that share a similar amino acid composition but vary i n their sulfur amino acid composition. They are synthesized on the rough endoplasmic reticulum (ER) in the endosperm and are stored in ER-derived protein bodies. Our goal i s to balance the amino acid composition of the methionine-deficient forage legumes by expressing the sulfur amino acid-rich 15-kD zeins in their leaves. However, it is crucial to know whelher this protein would be stable i n nonseed tissues of transgenic plants. The major focus of this paper is to compare the accumulation pattern of the 15-kD zein protein with a vacuolar targeted seed protein, p-phaseolin, in nonseed tissues and to determine the basis for i t s stability/instability. We have introduced the 15-kD zein and bean p-phaseolin-coding sequences behind the 35s cauliflower mosaic virus promoter into tobacco (Nicofiana fabacum) and analyzed the protein's accumulation pattern in different tissues. Our results demonstrate that the 15-kD seed protein i s stable not only i n seeds but in all nonseed tissues tested, whereas the P-phaseolin protein accumulated only i n mid-and postmaturation seeds. Interestingly, zein accumulates in novel protein bodies both in the seeds and in nonseed tissues. We attribute the instability of the p-phaseolin protein i n nonseed tissues to the fact that it is targeted to protease-rich vacuoles. The stability of the 15-kD zein could be attributed to its retention i n the ER or to the proteaseresistant nature of the protein.Seed storage proteins constitute a potentially useful class of proteins for the improvement of forage crops if they can be made to accumulate in leaves. It is a fairly simple genetic engineering feat to introduce a seed protein-coding sequence behind a strong constitutive promoter into transgenic plants and ensure high rates of synthesis of the corresponding protein. However, stability of the protein in an alien environment is still not clearly defined and has to be treated on a case by case basis.Seed proteins are synthesized during seed development and accumulate in protein bodies. These proteins are then utilized by the emerging seedling during germination. The major seed protein in dicotyledonous plants are the saltsoluble globulins, which are stored in vacuole-derived protein bodies. Most monocot seed storage proteins are '

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Section: Discussionsupporting

confidence: 55%

Accumulation of 15-Kilodalton Zein in Novel Protein Bodies in Transgenic Tobacco

et al. 1995

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“…As normal protein bodies mature, aggregates of a-zeins would coalesce within the central region of the p-and y-zein complex. In turn, the p-and y-zeins would become localized at the periphery of the protein bodies (Lending and Larkins, 1989). In contrast, locules of a-zeins would appear not at the center but at the periphery offl2 protein bodies, thereby displacing the p-and 7-zeins into the central region.…”

Section: Discussionmentioning

confidence: 99%

“…The assembly and packaging of different classes of zeins during endosperm development results in highly organized protein bodies (Esen, 1986;Lending and Larkins, 1989). This process might easily be disrupted as a consequence of an a-zein that either is inserted into the membrane or is incapable of folding properly.…”

Section: Discussionmentioning

confidence: 99%

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A Defective Signal Peptide Tethers the floury-2 Zein to the Endoplasmic Reticulum Membrane

et al. 1997

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The maize (Zea mays L.) floury-2 (f/Z) mutation is associated with a general decrease in storage protein synthesis, altered protein body morphology, and the synthesis of a novel 24-kD a-zein storage protein. Unlike storage proteins in normal kernels and the majority of storage proteins in f/Z kernels, the 24-kD a-zein contains a signal peptide that would normally be removed during protein synthesis and processing. The expected processing site of this a-zein reveals a putative mutation alanine-valine (Ala-Val) that is not found at other junctions between signal sequences and mature proteins. To investigate the impact of such a mutation on signal peptide cleavage, we have assayed the 24-kD f/Z a-zein in a co-translational processing system i n vitro. Translation of RNA from f/Z kernels or synthetic RNA encoding the f/Z a-zein in the presence of microsomes yielded a 24-kD polypeptide. A normal signal peptide sequence, generated by site-directed mutagenesis, restored the capacity of the RNA to direct synthesis of a properly processed protein i n a cell-free system. Both the f/Z a-zein and the f/Z a-zein (Val-Ala) were translocated into the lumen of the endoplasmic reticulum. The processed f/Z a-zein (ValbAla) was localized in the soluble portion of the microsomes, whereas the f/Z a-zein co-fractionated with the microsomal membranes. By remaining anchored t o protein body membranes during endosperm maturation, the f/Z zein may thus constrain storage protein packing and perturb protein body morphology.The maize (Zea mays L.) floury-2 fl2) mutation produces pleiotropic effects that include a soft, starchy endosperm, a reduction in the amount of endosperm storage protein, and changes in the arrangement of proteins within protein bodies (Nelson et al., 1965;Lending et al., 1988). The changes in protein packaging are accompanied by an accumulation of aberrant protein bodies near the nuclei of endosperm cells. Coincident with the appearance of the aberrant protein bodies is an increase in the accumulation

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“…Based on their molecular weight and sequence, they are classified into four classes, namely, a, b, g and d 5,6 . Similar to the maize zeins, kafirins are stored in the endoplasmic reticulum (ER) in spherical protein bodies (PBs), in which b-and g-kafirins are located in the peripheral PB region and a-and d-kafirins are encapsulated in the inner region 7,8 . The a-kafirins are the last proteins to be digested in the intestine and, because of their high abundance, the indigestibility reduces their nutritive value.…”

mentioning

confidence: 99%

Mutation in the seed storage protein kafirin creates a high-value food trait in sorghum

Yuan

Guo

et al. 2013

Nat Commun

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Sustainable food production for the earth's fast-growing population is a major challenge for breeding new high-yielding crops, but enhancing the nutritional quality of staple crops can potentially offset limitations associated with yield increases. Sorghum has immense value as a staple food item for humans in Africa, but it is poorly digested. Although a mutant exhibiting high-protein digestibility and lysine content has market potential, the molecular nature of the mutation is previously unknown. Here, building on knowledge from maize mutants, we take a direct approach and find that the high-digestible sorghum phenotype is tightly linked to a single-point mutation, rendering the signal peptide of a seed storage protein kafirin resistant to processing, indirectly reducing lysine-poor kafirins and thereby increasing lysine-rich proteins in the seeds. These findings indicate that a molecular marker can be used to accelerate introduction of this high nutrition and digestibility trait into different sorghum varieties.

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Changes in the zein composition of protein bodies during maize endosperm development.

Cited by 295 publications

References 11 publications

Accumulation of 15-Kilodalton Zein in Novel Protein Bodies in Transgenic Tobacco

Accumulation of 15-Kilodalton Zein in Novel Protein Bodies in Transgenic Tobacco

A Defective Signal Peptide Tethers the floury-2 Zein to the Endoplasmic Reticulum Membrane

Mutation in the seed storage protein kafirin creates a high-value food trait in sorghum

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