Expression of wild‐type and mutant forms of γ‐zein and γ‐gliadin in heterologous systems has demonstrated that the proline‐rich repetitive sequences are required for ER retention (Torrent et al., 1994; Geli et al., 1994; Altschuler et al., 1993; Altschuler and Galili, 1994), and it is possible that these regions form protein:protein interactions leading to the formation of insoluble accretions which accumulate directly in the ER rather than being transported to the Golgi and vacuole (Coleman and Larkins, 1999; Shewry, 1999). Bagga S, Adams H, Kemp JD, Sengupta‐Gopalan C. Bagga S, Adams H, Rodriquez FD, Kemp JD, Sengupta‐Gopalan C. Barro F, Rooke L, Békés F, Gras P, Tatham AS, Fido R, Lazzeri PA, Shewry PR, Barceó P. Bartels D, Altosaar I, Harberd NP, Barker RF, Thompson RD. A regulatory role for the prolamin box itself has been established previously (Müller and Knudsen, 1993; Hammond‐Kosack et al., 1993). (Taken from Bechtel et al., 1991, with permission.) The amounts of sulfate and thiols in seeds were decreased by antisense suppression of SULTR2;1, suggesting the function of this transporter is relevant to delivery of sulfate or sulfur metabolites to seeds. For example, a seed-specific promoter should be employed to change fatty acid synthesis pathways in oil seeds (see later). highly visco‐elastic) doughs contain high proportions of high molecular mass glutenin polymers (Field et al., 1983b). Similarly, sequence similarity is clearly present between the non‐repetitive domains of the S‐rich and HMW prolamins, particularly in positions of conserved cysteine residues and amino acid residues adjacent to these. Bread wheat is currently being transformed with a range of wild‐type and mutant genes encoding HMW subunits and other gluten proteins. This article describes an outline about SSPs, especially classification of SSPs, accumulation of SSPs in seed cells, decomposition of SSPs at seed germination stage, and novel application of SSPs by genetically modified technique. Nevertheless, proteins have major impacts on the end use properties of the grain. An increase in the degree of cross‐linking between gluten proteins in the transgenic lines may have resulted from the presence of a cysteine residue towards the N‐terminal end of the repetitive domain of subunit 1Dx5 (Fig. The conclusion is that some prolamins, principally gliadins, are transported via the Golgi to the protein storage vacuole whereas others, principally glutenins, are retained within the ER. Colot V, Robert LS, Kavanagh TA, Bevan MW, Thompson RD. Developing cotyledons of lupin shows significant rates of sulfate assimilation (Tabe and Droux, 2001). Journal of Molecular Evolution 41, 1070–1075. However, a motif involved in the response of S‐poor and S‐rich prolamin genes of wheat, barley and rye to nitrogen has been identified. The total protein content ranged from 22.4 (HC-3) to 27.9 % (HC-98-64) in 21 genotypes whereas in check Transgene expression also appeared to be restricted to starchy endosperm cells, and this was confirmed by the analysis of transgenic wheat lines in which the HMW subunit 1Dx5 gene promoter was used to drive the UidA reporter gene encoding β‐glucuronidase (Gus) (Lamacchia et al., 2001). The spherical protein bodies store prolamins and the irregular-shaped protein bodies accumulate glutelins. 3a) (Yamagata and Tanaka, 1986; Krishnan et al., 1986). A major class of seed storage proteins, the 2S albumins are usually synthesized in the seed as single chains of 10–15 kDa which may be post-translationally processed to give small and large subunits which usually remain joined by disulfide bonds. Thus, in addition to being identified in many different fruits and seeds, they have also been characterized as allergens in the pollen of several plant species such as olive and Parietaria judaica as well as inhalant allergens involved in occupational allergies to dusts such as wheat flour in Baker's asthma. These proteins accumulate within membrane-bound organelles called protein bodies (Figure 1). The N motif is at the 3′ end of the box and has the consensus sequence G(A/G)TGAGTCAT in S‐rich prolamin genes. The impact of the HMW subunit transgenes on dough strength has been determined on selected lines grown in the glasshouse (Barro et al., 1997; Rooke et al., 1999) and field plots (Popineau et al., 2001) using the Mixograph which measures the energy input during dough mixing. It has similarity with the binding site of the GCN4 transcription factor, which is a component of the nitrogen signalling pathway in yeast, and is sometimes called the GCN4‐like motif (GLM). β-Conglycinin is a soybean seed storage protein that accumulates under low-sulfur conditions and exhibits sulfur deficiency responses when expressed heterologously in Arabidopsis (Awazuhara et al., 2002; Hirai et al., 1995). Furthermore, the reactions are only induced by fresh fruits and the processed fruits and vegetables, such as commercial fruit juices, peach in syrup or cooked foods are tolerated. As described previously, SULTR2;1 is regulated by the sulfur status, displaying contrasting patterns of mRNA accumulation between roots and shoots (Takahashi et al., 2000). 2B). About 60% of plant-derived food allergens belong to just four protein families: cupins, prolamins, profilins, and pathogenesis-related proteins of the plant defense system (Jenkins et al., 2005). Bet v 1 is correlated with symptoms restricted to the mouth. It is also responsible for maintaining the three-dimensional structure of many of these proteins even after heating, which is associated with their retaining their allergenic properties after cooking and may contribute to their resistance to proteolysis. (c) Wheat at 11 d after flowering showing inclusions of triticin (dark staining, labelled I) within a matrix of prolamin (M). This revealed the presence of the conserved sequence, which is approximately 30 bp long, around 300 bp upstream of the transcription start site (it was first called the −300 element). Sequences corresponding to parts of the N and E motifs are present in HMW prolamin promoters upstream from the major enhancer (Lamacchia et al., 2001). Thus, they are synthesized on rough endoplasmic reticulum (ER) membranes, transported co‐translationally into the lumen and then pass via the Golgi apparatus into a specific population of protein storage vacuoles, which differ from the lytic vacuoles that are also present in developing seeds. Prolamins are a group of seed storage proteins and the main storage proteins in cereals and other members of the grass family. It is clear, therefore, that prolamin storage proteins are much more variable in structure than the 7S and 11/12S globulins, and it is possible that the major groups of prolamins in the Triticeae (wheat, barley, rye) and the Panicoideae (maize, sorghum, millets) have separate evolutionary origins. This association has been confirmed in many laboratories worldwide and has led to detailed studies of HMW subunit structure and properties. These low molecular weight proteins are cysteine rich and their three-dimensional structures are rich in α-helices (Breiteneder and Radauer, 2004). Prolamin genes are subject to tissue‐specific and developmental regulation, being expressed exclusively in the starchy endosperm during mid‐ and late‐development, and nutritional regulation, responding sensitively to the availability of nitrogen and sulphur in the grain (Duffus and Cochrane, 1992; Giese and Hopp, 1984). The expression of storage proteins is also regulated by nutrition. Understanding the structures of these proteins, their biophysical and functional properties, and the biological mechanisms which determine their synthesis, trafficking and deposition in the grain is important to underpin future attempts to improve the end use quality of grain by genetic engineering. We use cookies to help provide and enhance our service and tailor content and ads. Bäumlein, H., Braun, H., Kakhovskaya, I.A. The name of these proteins derives from the fact they were originally identified in plants because of their ability to transfer lipids in vitro, but their actual biological function in plants is unclear. Rice is one of the major staple cereal foods and is an important source of total protein in human food. The biological significance of the biophysical properties of gluten is unknown, as the proteins function essentially as grain storage proteins and have no known biological requirement to exhibit visco‐elasticity. Four laboratories have so far reported the expression of HMW subunit transgenes in bread wheat, in each case using either the gene's own promoter or that of another HMW subunit gene (Blechl and Anderson, 1996; Altpeter et al., 1996; Barro et al., 1997; Alvarez et al., 2000). Consequently, these cells contain high proportions of proteins, although the total protein content per cell varies little across the whole wheat endosperm (Evers, 1970). (b) Schematic structures of the Mr 19 000 (Z19) and Mr 22 000 (Z22) α‐zeins of maize. Oral feeding of GluB-1 to mice resulted in the induction of oral tolerance to pollen allergens.36 Furthermore, transgenic rice expressing CT-B using GluB-1 promoter successfully induced CT-B- specific immunity when orally immunized.36a. The major consideration is the impact of the grain proteins on functional properties for food processing, since the bulk of all cereals, except rice, are consumed in processed foods. Discussions of prolamin structure and properties can be confusing for the non‐expert because of the complexity of the fractions and their specialized nomenclature. Torrent M, Geli MI, Ruiz‐Avila L, Canals J, Puigdomènech P, Ludevid MD. Therefore, SSPs are closely related to our life. 33 000 in oats, 28–31 000 in rice) and basic (Mr approx. Oxford University Press is a department of the University of Oxford. This control of gene expression is exerted primarily at the transcriptional level (Bartels and Thompson, 1986; Sørensen et al., 1989). Rice SSPs are encoded by 15 glutelin and 34 prolamin genes and are mainly deposited in the endosperm, with glutelins being dominant. histidine, glycine, methionine, phenylalanine) in some prolamin groups. Anna Pomés, ... Martin D. Chapman, in Encyclopedia of Immunobiology, 2016. PB‐II are amorphous, derived from vacuolar deposition and contain globulins/glutelins. Seed Storage Proteins; Strategies for Deve loping Crops Promoting Human Health 245 Total protein was extracted from each of the transgenic seeds with SDS buffer. Cereal seed storage proteins are produced by the secretory pathway and deposited in discrete protein bodies. Seed storage proteins: structures and biosynthesis. Most of the wheat consumed by humans is processed from white flour, which is produced by milling to remove the germ (embryo) and bran (pericarp, testa, nucellar layer, and aleurone layer). To whom correspondence should be addressed. A second putative transcription factor, ESBF‐II, bound the N motif prior to maximum expression of the gene. Certain SSPs are also posttranslationally modified by glycosylation and phosphorylation (Lin et al., 2005; Onda et al., 2011). This results in nutritional deficiencies in these amino acids when the whole grain are fed to monogastric livestock such as pigs and poultry. However, to achieve optimum utilization of this crop for human and animal nutrition, both protein content and quality have to be improved. These experiments confirmed that the E and N motifs are separate elements and showed that the N motif exerts a negative effect on gene expression at low nitrogen levels and interacts with the E motif and other upstream elements to give high expression when nitrogen levels are adequate. Conclusion: The reduced coconut protein at 35 kd was previously shown to be immunologically similar to soy glycinin (legumin group of seed storage proteins). Premium Heirloom Seeds. The seeds of higher plants accumulate large quantities of storage protein. The cysteine skeleton and α-helical structure generally characteristic of the prolamin superfamily has been disrupted in the seed storage prolamins as a consequence of the insertion of a repetitive domain rich in the amino acids proline and glutamine. In addition, transport of sulfate or sulfur-containing compounds to seeds through the funiculus can be affected under both low- and high-sulfur conditions as apparent insensitivity of SULTR2;1 transcript control mechanisms to sulfur conditions was indicated for the siliques (Awazuhara et al., 2005). These proteins are characteristically insoluble in dilute salt solutions, either in the native state or after reduction of interchain disulfide bonds, being instead soluble in aqueous alcohols. The effect of seed storage proteins (SSPs) on seed longevity and seed dormancy. It has been claimed that proteins with >70% sequence identity are often cross-reactive, whereas those with <50% sequence identity rarely cross-react, although there are a few exceptions. Storage proteins account for about 50% of the total protein in mature cereal grains and have important impacts on their nutritional quality for humans and livestock and on their functional properties in food processing. subunits 1Dx5+1Dy10). SH denotes the positions of cysteine residues in the HMW prolamins. 1) because cysteine residues are not present in equivalent positions in other 1Dx subunits. used in vivo footprinting and gel retardation assays to show that E motifs within the prolamin box and further upstream in the promoter of a wheat low molecular weight (LMW) subunit gene bound a putative transcription factor, ESBF‐1 (Hammond‐Kosack et al., 1993). Results from a range of studies are consistent with the hypothesis that the HMW subunits form an elastomeric polymer network which provides a ‘backbone’ for interactions with other glutenin subunits and with gliadins. Globulin storage proteins do not contain cleavable pro‐domains which confer vacuolar targeting, but non‐cleavable segments within the mature protein sequence may be important (Kermode and Bewley, 1999). This confers visco‐elastic properties that allow the dough to be expanded by fermentation and baked into leavened bread or processed into pasta, noodles and a range of other foods. These groups do not correspond directly to the polymeric and monomeric fractions in wheat (glutenins and gliadins, respectively) recognized by cereal chemists, as both monomeric and polymeric forms of S‐rich and S‐poor prolamins occur. This repetitive domain dominates their physicochemical properties of the seed storage prolamins and is thought to adopt a loose spiral structure formed from a dynamic ensemble of unfolded and secondary structures comprising overlapping β-turns or poly-L-proline II structures. References The molecular basis for the visco‐elastic properties of wheat gluten has fascinated cereal scientists for many years as a phenomenon of fundamental interest as well as in relation to improving the end use properties of wheat flours. 3c) may result from the initial deposition of these components in separate populations of protein bodies (as in rice), which subsequently fuse. Krishnan, E.H. CoeJr, in Encyclopedia of Genetics, 2001. The gluten proteins form a continuous matrix in the mature dry endosperm cells, as discussed above. Rice has the lowest protein content among cereal grains, but net protein utilization is highest (Juliano, 1992). Popineau Y, Deshayes G, Lefebvre J, Fido RJ, Tatham AS, Shewry PR. Sensitization to LTPs has also been reported in patients with no pollen allergies, which supports their role as a sensitizing food allergen. ButardoJr., Nese Sreenivasulu, in International Review of Cell and Molecular Biology, 2016. 2). (Taken from Lending et al., 1989, with permission.) This motif (the N motif or nitrogen element) (Hammond‐Kosack et al., 1993; Muller and Knudsen, 1993) is present within a highly conserved sequence called the prolamin box. Hammond‐Kosack MCU, Holdsworth MJ, Bevan MW. For full access to this pdf, sign in to an existing account, or purchase an annual subscription. This comprises a bundle of four α-helices stabilized by disulfide bonds which are arranged in such a way as to create a lipid-binding tunnel in the nsLTPs which is collapsed in the 2S albumin structures. With the development and progress of protein separation technology, more and more non-prolamins have been studied. They are sorted into separate intracellular compartments depending on localization signals (Choi et al., 2000). However, it could also result from phase separation of the prolamin and globulin proteins due to their different structures and properties. Cell-specific gene expression in plants and a description of the different tissue-specific plant promoters are reviewed in detail by Edwards and Coruzzi (1990). In wheat, the prolamins form the major components of the gluten protein fraction which forms a viscoelastic network in doughs and is largely responsible for the ability to process wheat to form bread, pasta and many other food products. Because the aleurone cells continue to divide periclinally in the developing cereal endosperm the youngest cells are present in the sub‐aleurone layer and the oldest cells in the central part of the endosperm. aC‐type LMW subunits are essentially polymeric forms of α‐ and γ‐gliadins and D‐type LMW subunits polymeric ω‐gliadins. The storage proteins of cereals are of immense importance in determining the quality and end use properties of the grain. DuPont FM, Hurkman WJ, Tanaka CK, Chan R. Field JM, Shewry PR, Burgess SR, Forde J, Parmar S, Miflin BJ. The ribulose–1,5-bisphosphate carboxylase small subunit (rbcS) gene promoter (Fluhr et al., 1986) and the chlorophyll a/b binding protein (Cab) gene promoter (Fluhr et al., 1986; Simpson et al., 1985) confer leaf-specific and light-dependent expression of genes. The review also includes some recent achievements in modifying soybean seed composition. PubMed CrossRef Google Scholar Hammond‐Kosack et al. (Taken from Coleman et al., 1999, with permission. The nutritional quality of cereals is not generally an important consideration for human diets in the developed world, although it is still important in some developing countries. The seed storage proteins are made as large precursors, then hydrolyzed to smaller products for the seedling’s use during growth. Andreas E. Voloudakis, ... N. Beachy, in Gene Expression Systems, 1999. A 10-year-old girl reported tingling and pruritus of the lips, mouth and oropharynx after ingestion of peach, carrot, apple, cherry and tomato. Most SSP transcripts are exclusively expressed in the developing seeds at 7–14 days postanthesis (Nie et al., 2013; Venu et al., 2011). Whether you are growing for market, or your own home, MIgardener is pleased to provide over 700 rare and unique vegetable, fruit, and flower seeds. The type of this processing depends on the plant species,those in sunflower being single-chain albumins and those in Brazil nut being two-chain albumins. However, recent work carried out with different gliadin fractions indicates that separation could occur, resulting in the formation of microphases. Mature 11S globulins or legumins are hexameric proteins. In vitro specific IgE tests show the following results: Prick-by-prick test with fresh fruits and vegetables was positive for peach, cherry and carrot, but negative for tomato as evaluated in mm wheal/erythema. 2). Processing quality is particularly important for wheat where the gluten proteins are the major determinant of end use quality. CS-88 and V-240 of cowpea [Vigna unguiculata (L.) Walp. ] Most recently, T-cell epitope peptides of allergens of Japanese cedar pollen have been expressed under the control of the rice seed storage protein glutelin (GluB-1) promoter. Thus, co‐expression of γ‐zein was required for the accumulation of α‐zein in transgenic tobacco (Coleman et al., 1996) while β‐ and δ‐zeins formed abnormal protein bodies when expressed alone in tobacco, but apparently normal protein bodies when expressed together (Bagga et al., 1995, 1997). The high content of globulin storage proteins in oat grain may contribute to the high nutritional value when compared with other cereals, such as barley and wheat, an important factor in view of the widespread use of oats for livestock feed (Lockhard and Hurt, 1986; Cuddeford, 1995). In the developing siliques of Arabidopsis, the expression of SULTR2;1 was found in the vasculatures and the base of seed pods, and in the funiculus connected to seeds. 5). Storage globulins The embryo and outer aleurone layer of the endosperm contain globulin storage proteins, and those from maize embryos have been characterized in some detail ( Kriz, 1989 , 1999 ; Kriz and Schwartz, 1986 ; Kriz and Wallace, 1991 ; Wallace and Kriz, 1991 ). Zein gene promoters, for example, contain a highly conserved 15 bp element that has been suggested to act as a tissue‐specific enhancer (Quayle and Feix, 1992). Plant LTPs have a total number of amino acids varying from 91 to 95 residues and exhibit strong structural homologies.18 Nevertheless, no sequence homology has been found between LTPs from mammalian and plant LTPs. The rice proteins are not readily soluble in dilute salt solutions and hence are classically defined as glutelins, but they clearly belong to the 11–12S globulin family. The major seed storage proteins of common bean are phaseolin (vicilin-like 7S globulin) and phytohemagglutinins (PHA). It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. Seed storage proteins of grain crops meet the major dietary protein requirement of over half of the world population. However, they do not appear to be absolutely required for normal seed function, at least in maize, where a null mutant behaves normally in terms of development and germination (Kriz and Wallace, 1991). This is particularly important in wheat, which is largely consumed by humans after processing into bread and other foods. Apart from the seed storage prolamins, which are characterized by the insertion of an extensive repetitive domain, members of this superfamily share a common three-dimensional structure. sorghum and many millets) are comprised of one major group of proteins (α‐zeins) and several minor groups (β, γ, δ‐zeins) (Coleman and Larkins, 1999; Leite et al., 1999) (Fig. The sub‐aleurone cells of both species are rich in proteins, but immunocytochemical and pearling studies of barley show that they contain mainly S‐rich and S‐poor prolamins (principally B and C hordeins), with the HMW prolamin (D hordein) only occurring in significant amounts below the sub‐aleurone (Shewry et al., 1996; Tecsi et al., 2000). The prolamin box in its entirety is also not present in HMW prolamin gene promoters (Shewry et al., 1999). LTPs are characterized by a conserved pattern of 6–8 cysteines, forming three to four disulfide bridges. The element contains the sequence TGCAAAG, which is similar to the E motif sequence TGTAAAG that is also present in zein genes, but it does not contain anything resembling the N motif. In general, seed storage proteins do not carry out any enzymatic functions. For resistance breeding, it is interesting to see that in a few cases, gene silencing can induce durable resistance against pathogens, as shown earlier with the recessive natural mlo loss-of-function mutations in barley, causing broad spectrum mildew resistance. They are the major seed storage proteins of the related cereals wheat, barley and rye, those from wheat being able to form large disulfide-linked polymers that comprise the viscoelastic protein fraction known as gluten. Structures of typical S‐rich, S‐poor and HMW prolamins of wheat are summarized in Fig. Müller and Knudsen used an homologous, transient expression system, involving particle bombardment of cultured barley endosperms with C hordein promoter/β‐glucuronidase (GUS) constructs. Because their expression is regulated by abiotic stress, belonging to pathogenesis-related protein group 14, they may have a role in plant protection. Meaning of SEED STORAGE PROTEINS. Together, the results of these experiments suggest that the N motif is an important component of the nitrogen regulatory mechanism for S‐rich and S‐poor prolamin genes. In the last 15 years, several studies have shown an immunologic cross-reactivity within LTPs from Rosaceae17 and between LTPs from Rosaceae and botanically unrelated plant-derived foods.21 The spectrum of foods in which the role of LTP as an allergen is being studied is increasing rapidly.
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