Disulphide structure of a sunflower seed albumin: conserved and variant disulphide bonds in the cereal prolamin superfamily

Through a twin-screw extrusion process the native structure of sunflower oil cake was completely transformed (globular protein denaturation/texturization and husk fiber defibration) into a simpler matrix-fiber structure, as could be seen on SEM micrographs. Further chemical reduction of protein disulfide bridges greatly reduced the melt viscosity of the moistened composite that it could be injection-molded. The molded specimens were tested and their tensile and flexural properties and water absorption calculated. Their water resistance appeared to be particularly high, and could be enhanced further after a thermal treatment (N 2 , 200°C). The proteic matrix seemed to behave like a natural thermoset resin. Sunflower oil cake could be used without any additives to make biodegradable, water resistant and exceptionally cheap materials.

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“…Cysteine bridges of sunflower albumins have been mapped (Egorov et al, 1996) (Kalapathy et al, 1996).…”

Section: Resultsmentioning

confidence: 99%

New natural injection-moldable composite material from sunflower oil cake

Rouilly

Orliac

Silvestre

et al. 2006

Bioresource Technology

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“…Cysteine residues corresponding to cysteine 134 and cysteine 169 can be identified in plant proteins sharing little sequence homology, such as sunflower SFA8, lupin conglutin ␦, and cereal ␣-amylase/trypsin inhibi-tors (11). It would be now interesting to check whether the specific role played by these residues has been conserved throughout the evolution of seed proteins.…”

Section: Discussionmentioning

confidence: 99%

“…Intrachain and interchain disulfide bonds cannot be unequivocally distinguished by these chemical mapping studies, but the presence of three intrachain disulfide bonds in LMW glutenin subunits can be inferred by analogy with the situation found in monomeric gliadins (6 -9) and on the basis of in vitro refolding studies (10). The position of some of the cysteine residues that are involved in these intrachain disulfide bonds is conserved not only in gliadin polypeptides but also in cereal ␣-amylase/trypsin inhibitors and in 2S albumin storage proteins (11). This suggests that all these proteins may share a common fold in which disulfide bonds play an important and perhaps essential role.…”

mentioning

confidence: 99%

Role of Individual Disulfide Bonds in the Structural Maturation of a Low Molecular Weight Glutenin Subunit

Orsi¹,

Sparvoli²,

Ceriotti³

2001

Journal of Biological Chemistry

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Gliadins and glutenins are the major storage proteins that accumulate in wheat endosperm cells during seed development. Although gliadins are mainly monomeric, glutenins consist of very large disulfide-linked polymers made up of high molecular weight and low molecular weight subunits. These polymers are among the largest protein molecules known in nature and are the most important determinants of the viscoelastic properties of gluten. As a first step toward the elucidation of the folding and assembly pathways that lead to glutenin polymer formation, we have exploited an in vitro system composed of wheat germ extract and bean microsomes to examine the role of disulfide bonds in the structural maturation of a low molecular weight glutenin subunit. When conditions allowing the formation of disulfide bonds were established, the in vitro synthesized low molecular weight glutenin subunit was recovered in monomeric form containing intrachain disulfide bonds. Conversely, synthesis under conditions that did not favor the formation of disulfide bonds led to the production of large aggregates from which the polypeptides could not be rescued by the post-translational generation of a more oxidizing environment. These results indicate that disulfide bond formation is essential for the conformational maturation of the low molecular weight glutenin subunit and suggest that early folding steps may play an important role in this process, allowing the timely pairing of critical cysteine residues. To determine which cysteines were important to maintain the protein in monomeric form, we prepared a set of mutants containing selected cysteine to serine substitutions. Our results show that two conserved cysteine residues form a critical disulfide bond that is essential in preventing the exposure of adhesive domains and the consequent formation of aberrant aggregates.Gliadins and glutenins are the major storage proteins that accumulate in wheat endosperm cells and are largely responsible for the unique suitability of wheat flour for bread-making. Because of their nutritional and technological importance, these proteins have been the target of a variety of studies concerning their biochemical features, their synthesis and intracellular transport (1).The polymerization state is a critical feature distinguishing gliadins from glutenins. Although gliadins (which are divided into ␣, ␥, and types) are largely recovered in monomeric form, glutenins consist of large polymers whose building blocks are the high molecular weight (HMW) 1 and the low molecular weight (LMW) glutenin subunits. High molecular weight glutenin subunits are constituted by a central repetitive domain flanked by two nonrepetitive regions containing cysteine residues critical for glutenin cross-linking. Two regions can instead be recognized in the primary structure of LMW glutenin subunits; one region is an N-terminal domain largely made up of repeated sequences, and the other is a C-terminal domain of unique sequence, where all the intrachain disulfide bonds are located (Fi...

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“…38 Therefore, determination of the disulphide connectivities is an essential experimental first step towards modelling and elucidating the full protein structure. In order to confirm the CD results and ascertain whether the Ber e 1, despite being glycosylated, is properly folded, disulphide mapping was undertaken.…”

Section: Disulphide Mappingmentioning

confidence: 99%

The Disulphide Mapping, Folding and Characterisation of Recombinant Ber e 1, an Allergenic Protein, and SFA8, Two Sulphur-rich 2S Plant Albumins

Alcocer

Murtagh

Bailey

et al. 2002

Journal of Molecular Biology

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We have cloned and expressed genes encoding the allergenic brazil nut 2 S albumin (Ber e 1) and the sunflower albumin 8 (SFA8) in the methylotrophic yeast Pichia pastoris. We show that both proteins were secreted at high levels and that the purified proteins were properly folded. We also showed that Ber e 1 is glycosylated during secretion and that the glycan does not interfere with the folding or immunoreactivity. The disulphide map of the Ber e 1 protein was experimentally established and is in agreement with the conserved disulphide structure of other members of the 2 S albumin family. A model three-dimensional structure of the allergen was generated. During the expression studies and through mutation we have also shown that alteration of the sequences around the Kex2 endoproteolytic processing site in the expressed fusion protein can compromise the secretion by targeting part of the protein for possible degradation. The secreted production of these properly folded sulphurrich plant albumins presents an opportunity to delineate the attributes that make an allergen and to facilitate the diagnosis and therapy of type I allergy.

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Disulphide structure of a sunflower seed albumin: conserved and variant disulphide bonds in the cereal prolamin superfamily

Cited by 35 publications

References 12 publications

New natural injection-moldable composite material from sunflower oil cake

New natural injection-moldable composite material from sunflower oil cake

Role of Individual Disulfide Bonds in the Structural Maturation of a Low Molecular Weight Glutenin Subunit

The Disulphide Mapping, Folding and Characterisation of Recombinant Ber e 1, an Allergenic Protein, and SFA8, Two Sulphur-rich 2S Plant Albumins

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