Mal d 1 (Bet-v-1-homologue Protein)

Allergen Data Collection - Update: Apple (Malus domestica)
Internet Symposium on Food Allergens 2(Suppl.4): 1-23 (2000) [http://www.food-allergens.de]

6.2 Properties of Bet v 1 - homologous Protein (Mal d 1)

6.2.1 Molecular Biological Properties

Bet-v-1-homologous Protein References

Allergen Nomenclature Mal d 1 (1) Larsen & Lowenstein 1999

Molecular Mass
18 kDa (1), 17 kDa (2) (SDS-PAGE) (1) Vieths et al. 1994c, Hsieh et al. 1995
(2) Ebner et al. 1995

Isoelectric Point pI 5.5 (2D-PAGE)
(1) Vieths et al. 1994c

Amino Acid Sequence, mRNA, and cDNA

Mal d 1 a) b) c)

SWISS-PROT: P43211 P43211

GenBank: X83672 L42952 Z48969

Amino Acids 158 160 158

mRNA 813 bp 778 bp 824 bp

cDNA

(a) Granny Smith, (b, c) Golden Delicious (1) Vanek-Krebitz et al. 1995
(2) Atkinson et al. 1996
(3) Hoffmann-Sommergruber et al. 1996
(4) Schöning et al. 1996

Genetic Variants
2 different isoforms from Golden Delicious and Granny Smith. Sequences from other strains (Jamba, Gloster, Royal Gala, Jonagold, and Idared) are identical to one of these isoallergens (1) (1) Son et al. 1999

recombinant Protein
Expression in Escherichia coli:
rMal d 1 from Golden Delicious (1)
rMal d 1 from Granny Smith (2)
rMal d 1 isoallergens and mutants from Golden Delicious and Granny Smith (4)
Expression in cDNA library:
rMal d 1 expressed sequence tags (ESTs) generated from selected clones of cDNA libraries prepared from Fuji apple (Malus domestica Borkh.) (3)
(1) Vanek-Krebitz et al. 1995
(2) Schöning et al. 1996
(3) Sung et al. 1998
(4) Son et al. 1999

Biological Function
Bet v 1 family of pathogenisis-related proteins (1) (1) SWISS-PROT

Sequence Homology
Bet v 1, major birch pollen allergen: aa 64.5% identity (1), mRNA 55.6% identity (1)
Pollen allergens from Alder (Aln g 1), Hazel (Cor a 1), and Hornbeam (Car b 1): aa 54%, 54%, and 52% identity (2)
Stress induced protein from soybean (GMH4): aa 49% identity (2)
Pea pathogenesis related protein (PEADRRA): aa 48% identiy (2)
5 Bet v 1 isoforms and 3 Mal d 1 isoforms share 55.6-58.8% aa identity (3) (1) Vanek-Krebitz et al. 1995
(2) Vieths et al. 1996
(3) Son et al. 1999

Localization
Expression of Mal d 1 in fruits, peels, and mature flowers from Fuji apple (Malus domestica Borkh.) (expressed sequence tags (ESTs) from randomly selected clones of cDNA libraries) (1) (1) Sung et al. 1998

6.2.2 Allergenic Properties

Bet v 1 - homologous Protein References

Frequency of Sensitization
IgE-binding to Mal d 1 in 73 % and 76 % of patients (1) (1) see 6.1 Sensitization to Apple Allergens

Allergenic Potencies
No significant differences in IgE binding potencies between 3 recombinant Mal d 1 isoforms and native Mal d 1 from 7 apple strains, divergent allergenicity of apple strains depends mainly on different expression levels; highest IgE-binding capacity for 2 isoforms from Golden Delicious and Granny Smith (EAST, immunoblot) (1) (1) Son et al. 1999

IgE-Binding: Critical Amino Acids
Strong reduction of IgE binding to 2 mutants S111P (single aa substitution) of recombinant Mal d 1 from Golden Delicious and Granny Smith as compared to non-mutated rMal d 1; only weak reduction of IgE-binding observed for S111C mutants (EAST, immunoblot) (1) (1) Son et al. 1999

T-Cell Epitopes
Specific T-cell proliferation with:
Mal d 1 aa 141-155 (synthetic peptide) (1)
T-cell proliferation after stimulation with Mal d 1 weaker than with Bet v 1 (1) (1) Fritsch et al. 1998

Cross-reative T-Cell Epitopes from Bet v 1
Specific proliferation of rMal d 1 induced T-cell clones:
Bet v 1 aa 4-18, 13-27, 55-66, 76-90, 109-123, 142-156 (synthetic peptides) (1) (1) Fritsch et al. 1998

T-Cells / Cytokines
69% of Mal d 1 / Bet v 1 cross-reactive T-cell clones revealed a Th2-like cytokine production pattern (26% Th0- and 5% Th1-like), none of the non-cross-reactive Mal d 1 specific T-cell clones was Th2-like (1) (1) Fritsch et al. 1998

Bet v 1 - homologous Protein	References
*Frequency of Sensitization* IgE-binding to Mal d 1 in 73 % and 76 % of patients (1)	(1) see 6.1 Sensitization to Apple Allergens
*Allergenic Potencies* No significant differences in IgE binding potencies between 3 recombinant Mal d 1 isoforms and native Mal d 1 from 7 apple strains, divergent allergenicity of apple strains depends mainly on different expression levels; highest IgE-binding capacity for 2 isoforms from Golden Delicious and Granny Smith (EAST, immunoblot) (1)	(1) Son et al. 1999
*IgE-Binding: Critical Amino Acids* Strong reduction of IgE binding to 2 mutants S111P (single aa substitution) of recombinant Mal d 1 from Golden Delicious and Granny Smith as compared to non-mutated rMal d 1; only weak reduction of IgE-binding observed for S111C mutants (EAST, immunoblot) (1)	(1) Son et al. 1999
*T-Cell Epitopes* Specific T-cell proliferation with: Mal d 1 aa 141-155 (synthetic peptide) (1) T-cell proliferation after stimulation with Mal d 1 weaker than with Bet v 1 (1)	(1) Fritsch et al. 1998
*Cross-reative T-Cell Epitopes from Bet v 1* Specific proliferation of rMal d 1 induced T-cell clones: Bet v 1 aa 4-18, 13-27, 55-66, 76-90, 109-123, 142-156 (synthetic peptides) (1)	(1) Fritsch et al. 1998
*T-Cells / Cytokines* 69% of Mal d 1 / Bet v 1 cross-reactive T-cell clones revealed a Th2-like cytokine production pattern (26% Th0- and 5% Th1-like), none of the non-cross-reactive Mal d 1 specific T-cell clones was Th2-like (1)	(1) Fritsch et al. 1998