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2S Albumin Storage Proteins: What Makes them Food Allergens?

Moreno FJ, Clemente A - Open Biochem J (2008)

Bottom Line: This review describes the main biochemical, structural and functional properties of these proteins thought to play a role in determining their potential allergenicity. 2S albumins are considered to sensitize directly via the gastrointestinal tract (GIT).The flexible and solvent-exposed hypervariable region of these proteins is immunodominant and has the ability to bind IgE from allergic patients sera.Finally, the interaction of these proteins with other components of the food matrix might influence the absorption rates of immunologically reactive 2S albumins but also in their immune response.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Fermentaciones Industriales (CSIC), C/ Juan de la Cierva 3, 28006 Madrid, Spain.

ABSTRACT
2S albumin storage proteins are becoming of increasing interest in nutritional and clinical studies as they have been reported as major food allergens in seeds of many mono- and di-cotyledonous plants. This review describes the main biochemical, structural and functional properties of these proteins thought to play a role in determining their potential allergenicity. 2S albumins are considered to sensitize directly via the gastrointestinal tract (GIT). The high stability of their intrinsic protein structure, dominated by a well-conserved skeleton of cysteine residues, to the harsh conditions present in the GIT suggests that these proteins are able to cross the gut mucosal barrier to sensitize the mucosal immune system and/or elicit an allergic response. The flexible and solvent-exposed hypervariable region of these proteins is immunodominant and has the ability to bind IgE from allergic patients sera. Several linear IgE-binding epitopes of 2S albumins spanning this region have been described to play a major role in allergenicity; the role of conformational epitopes of these proteins in food allergy is far from being understood and need to be investigated. Finally, the interaction of these proteins with other components of the food matrix might influence the absorption rates of immunologically reactive 2S albumins but also in their immune response.

No MeSH data available.


Related in: MedlinePlus

Multiple primary sequence alignment of allergenic 2S albumins from different species (Ara h 6, peanut; Ber e 1, Brazil nut; Bra j 1, oriental mustard; BnIa and Bra n 1, rapeseed; Gly m 2S albumin, soya; Mat5-D, upland cotton; SFA-8, sunflower seed; Lup a 2S albumin, lupin; Ric c 1 and Ric c 3, castor bean; Ses i 1 and Ses i 2, sesame seed; Sin a 1, yellow mustard) by using T-COFFEE (slow pair method) [140]. Numbers indicate the sequence position. Asterisks represent residue conservation among all the sequences.
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Figure 2: Multiple primary sequence alignment of allergenic 2S albumins from different species (Ara h 6, peanut; Ber e 1, Brazil nut; Bra j 1, oriental mustard; BnIa and Bra n 1, rapeseed; Gly m 2S albumin, soya; Mat5-D, upland cotton; SFA-8, sunflower seed; Lup a 2S albumin, lupin; Ric c 1 and Ric c 3, castor bean; Ses i 1 and Ses i 2, sesame seed; Sin a 1, yellow mustard) by using T-COFFEE (slow pair method) [140]. Numbers indicate the sequence position. Asterisks represent residue conservation among all the sequences.

Mentions: Despite the skeleton of cysteine residues of 2S albumins being highly conserved, a relatively low amino acid sequence homology, within and among plant species, can be observed. Figs. (2 and 3) illustrate the alignment of the primary structure and the generated dendrogram based on amino acid sequence similarity of major allergens of the 2S protein family. As expected, regions spanning the cysteine residues showed the highest amino acid sequence homology whereas the regions showing the lowest amino acid sequence homology corresponded to i) the C-terminal of the small subunit, ii) the NH2-terminal of the large subunit and iii) that contained between the sixth and seventh cysteine residues within the large subunit. Overall, the degree of sequence homology of 2S allergens is low, ranging from 14 to 40 %, and does not reflect phylogenetic relationships, with the exception of 2S albumins belonging to the Brassicaceae family (i.e., Bra j 1, BnIa, Bra n 1 and Sin a 1) (Table 2). A high amino acid sequence polymorphism has been also found in 2S albumins belonging to the same specie, as occur with allergens from sesame (Ses i 1 and Ses i 2) or castor bean (Ric c 1 and Ric c 3) (Table 2).


2S Albumin Storage Proteins: What Makes them Food Allergens?

Moreno FJ, Clemente A - Open Biochem J (2008)

Multiple primary sequence alignment of allergenic 2S albumins from different species (Ara h 6, peanut; Ber e 1, Brazil nut; Bra j 1, oriental mustard; BnIa and Bra n 1, rapeseed; Gly m 2S albumin, soya; Mat5-D, upland cotton; SFA-8, sunflower seed; Lup a 2S albumin, lupin; Ric c 1 and Ric c 3, castor bean; Ses i 1 and Ses i 2, sesame seed; Sin a 1, yellow mustard) by using T-COFFEE (slow pair method) [140]. Numbers indicate the sequence position. Asterisks represent residue conservation among all the sequences.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2570561&req=5

Figure 2: Multiple primary sequence alignment of allergenic 2S albumins from different species (Ara h 6, peanut; Ber e 1, Brazil nut; Bra j 1, oriental mustard; BnIa and Bra n 1, rapeseed; Gly m 2S albumin, soya; Mat5-D, upland cotton; SFA-8, sunflower seed; Lup a 2S albumin, lupin; Ric c 1 and Ric c 3, castor bean; Ses i 1 and Ses i 2, sesame seed; Sin a 1, yellow mustard) by using T-COFFEE (slow pair method) [140]. Numbers indicate the sequence position. Asterisks represent residue conservation among all the sequences.
Mentions: Despite the skeleton of cysteine residues of 2S albumins being highly conserved, a relatively low amino acid sequence homology, within and among plant species, can be observed. Figs. (2 and 3) illustrate the alignment of the primary structure and the generated dendrogram based on amino acid sequence similarity of major allergens of the 2S protein family. As expected, regions spanning the cysteine residues showed the highest amino acid sequence homology whereas the regions showing the lowest amino acid sequence homology corresponded to i) the C-terminal of the small subunit, ii) the NH2-terminal of the large subunit and iii) that contained between the sixth and seventh cysteine residues within the large subunit. Overall, the degree of sequence homology of 2S allergens is low, ranging from 14 to 40 %, and does not reflect phylogenetic relationships, with the exception of 2S albumins belonging to the Brassicaceae family (i.e., Bra j 1, BnIa, Bra n 1 and Sin a 1) (Table 2). A high amino acid sequence polymorphism has been also found in 2S albumins belonging to the same specie, as occur with allergens from sesame (Ses i 1 and Ses i 2) or castor bean (Ric c 1 and Ric c 3) (Table 2).

Bottom Line: This review describes the main biochemical, structural and functional properties of these proteins thought to play a role in determining their potential allergenicity. 2S albumins are considered to sensitize directly via the gastrointestinal tract (GIT).The flexible and solvent-exposed hypervariable region of these proteins is immunodominant and has the ability to bind IgE from allergic patients sera.Finally, the interaction of these proteins with other components of the food matrix might influence the absorption rates of immunologically reactive 2S albumins but also in their immune response.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Fermentaciones Industriales (CSIC), C/ Juan de la Cierva 3, 28006 Madrid, Spain.

ABSTRACT
2S albumin storage proteins are becoming of increasing interest in nutritional and clinical studies as they have been reported as major food allergens in seeds of many mono- and di-cotyledonous plants. This review describes the main biochemical, structural and functional properties of these proteins thought to play a role in determining their potential allergenicity. 2S albumins are considered to sensitize directly via the gastrointestinal tract (GIT). The high stability of their intrinsic protein structure, dominated by a well-conserved skeleton of cysteine residues, to the harsh conditions present in the GIT suggests that these proteins are able to cross the gut mucosal barrier to sensitize the mucosal immune system and/or elicit an allergic response. The flexible and solvent-exposed hypervariable region of these proteins is immunodominant and has the ability to bind IgE from allergic patients sera. Several linear IgE-binding epitopes of 2S albumins spanning this region have been described to play a major role in allergenicity; the role of conformational epitopes of these proteins in food allergy is far from being understood and need to be investigated. Finally, the interaction of these proteins with other components of the food matrix might influence the absorption rates of immunologically reactive 2S albumins but also in their immune response.

No MeSH data available.


Related in: MedlinePlus