Sequence from Haliotis asinina, Haliotis diversicolor and Haliotis rufescens are available but only that from Haliotis diversicolor has been identified as an allergen.
The allergenicity of tropomyosins can survive cooking, possibly because tropomyosin have a very simple helical structure which can rapidly refold after denaturation. Extracts from cooked abalone give similar immunoblots to extracts from raw abalone.
Nature of main cross-reacting proteins:
The immunoblotting results of Lopata et al (1997) [1188] suggest that there is IgE cross-reactivity for tropomyosins between abalone and snail, white mussel, black mussel, oyster, and squid.
More generally, Leung et al (1996) [1557] demonstrated cross-reactivity between tropomyosins from arthropods (crustacea and insects), tropomyosins from gastropods: abalone (Haliotis diveriscolor) and whelk (Hemifusus ternatana), bivalves: mussel (Perna viridis), pen shell (Pinna atropupurea), scallop, oyster (Crassostrea gigas) and clam (Lutraria philipinarum) and cephalopods: cuttlefish (Sepia madokai), squid (Loligo edulis) and octopus ((Octopus luteus).
Chu et al (2000) [1189] also demonstrate IgE cross-reactivity by using recombinant tropomyosins from the abalone Haliotis diversicolor, the scallop Chlamys nobilis, and the mussel Perna viridis to inhibit IgE binding of shrimp allergic sera to shrimp extracts.
Allergen properties & biological function:
Tropomyosins bind to actin in muscle increasing thin filament stability and rigidity. Depolymerization from the pointed end is inhibited, without affecting elongation (Broschat, 1990 [1589]). As tropomyosin prevents the binding of myosin, it may play an important role with troponin in controlling muscle contraction. The sequence exhibits a prominent seven-residues periodicity and this is reflected in the interactions of the 2 polypeptide chains which form a coiled coil structure of two alpha-helices as originally proposed by Crick in 1952 (see the porcine structure 1C1G). Some tropomyosins are N-acetylated modifying the structure of the N terminal region and increasing the affinity for the thin filaments (Greenfield & Fowler, 2002 [1590]).
Allergen purification:
Production of recombinant abalone, Haliotis diversicolor, tropomyosin as a fusion protein has been reported (Chu et al. 2000 [1189]).
Other biochemical information:
The sequences of tropomyosins from abalone are rather similar to each other with sequences from Haliotis asinina Q7YZR4, Haliotis diversicolorQ9GZ71 and Haliotis rufescensQ25145 being 97-98% identical. A second sequence from Haliotis asininaQ7YZR3 is approximately 94% identical with these. The sequence from another gastropod, the snail Helix aspersa, O97192, is 86% identical. The bivalues show slightly lower levels of identity with oysters, scallops, mussels and clams having 70-80% sequence identity. Arthropod sequences are typically 57-63% identical and vertebrate sequences approximately 55% identical.
Lu et al. (2004) [1190] report a single monoclonal antibody against Japanese abalone (Haliotis discus) tropomyosin which distinguishes abalone from other mollusks.
References (7)
Broschat KO.
Tropomyosin prevents depolymerization of actin filaments from the pointed end.
J Biol Chem. 265(34):21323-21329. 1990
PUBMED ID:
2250026
Chu KH, Wong SH, Leung PS.
Tropomyosin Is the Major Mollusk Allergen: Reverse Transcriptase Polymerase Chain Reaction, Expression and IgE Reactivity.
Mar Biotechnol (NY). 2(5):499-509.
2000
PUBMED ID:
11246417
Jeoung BJ, Reese G, Hauck P, Oliver JB, Daul CB, Lehrer SB.
Quantification of the major brown shrimp allergen Pen a 1 (tropomyosin) by a monoclonal antibody-based sandwich ELISA.
J Allergy Clin Immunol. 100(2):229-234. 1997
PUBMED ID:
9275145
Leung PS, Chow WK, Duffey S, Kwan HS, Gershwin ME, Chu KH.
IgE reactivity against a cross-reactive allergen in crustacea and mollusca: evidence for tropomyosin as the common allergen.
J Allergy Clin Immunol. 98(5 Pt 1):954-961.
1996
PUBMED ID:
8939159
Lopata AL, Zinn C, Potter PC.
Characteristics of hypersensitivity reactions and identification of a unique 49 kd IgE-binding protein (Hal-m-1) in abalone (Haliotis midae).
J Allergy Clin Immunol. 100(5):642-648. 1997
PUBMED ID:
9389294
Lu Y, Oshima T, Ushio H, Shiomi K.
Preparation and characterization of monoclonal antibody against abalone allergen tropomyosin.
Hybrid Hybridomics. 23(6):357-361.
2005
PUBMED ID:
15684662
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