Purification, Characterization, and Three-Dimensional Structure Prediction of Paramyosin, a Novel Allergen of Rapana venosa

Abstract

Paramyosin (PM) is an important structural protein in molluscan muscles. However, as an important allergen, there is a little information on PM in the molluscs. In this study, a 99 kDa molecular weight allergen protein was purified from Rapana venosa and confirmed as PM by mass spectrometry. The results of immunoglobulin E (IgE)-binding activity and physicochemical characterization showed that R. venosa PM could react with a specific IgE of the sera from sea snail-allergic patients, and the IgE-binding activity could be reduced by thermal treatment. The full-length cDNA of R. venosa PM was cloned, which encodes 859 amino acid residues, and it has a higher homology among molluscan species. According to the circular dichroism results, Fourier transform infrared, and 2D and 3D structure analysis, both PM and tropomyosin are conserved proteins, which are mainly composed of the α-helix structure. These results are significant for better understanding the anaphylactic reactions in sea snail-allergic patients and allergy diagnosis.

Effects of Extraction Buffer on the Solubility and Immunoreactivity of the Pacific Oyster Allergens

“…Moreover, the structural stability of this protein is susceptible to heat treatment, further affecting its IgE-binding capacity. A recent study by Yu et al confirmed our finding that paramyosin is not heat stable, and we verified this using different buffers [31]. Nonetheless, it was observed in the Carbonate-10 extract that paramyosin content was relatively high and its IgE-binding capacity was still maintained following heat treatment.…”

“…One of the very prominent IgE-reactive bands is paramyosin, observed at 100 kDa. Paramyosin is a major structural component of the invertebrate muscle thick filament and was identified as an additional major allergen in abalone (Haliotis discus discus) [7,30] and recently in sea snail (Rapana venosa) [31]. The discovery of allergenic paramyosin in mollusc species was not surprising since this protein has been confirmed as a major allergen in other invertebrates such as house dust-mite [32] and anisakis [33].…”

Seafood Allergy in Asia: Geographical Specificity and Beyond

“…This protein reacted with 16 of the 18 Japanese sera from allergic subjects being studied. They also reported IgE reactivity against paramyosins from turban shell, mussel, scallop, squid and octopus, which was subsequently found in the Asian rapa whelk Rapana venosa (71). Interestingly, paramyosin is a heat-labile protein so the clinical relevance of paramyosin would be limited to some Asian populations such as Japanese and Koreans where mollusks and abalone are served as sashimi.…”

Newly defined allergens in the WHO/IUIS Allergen Nomenclature Database during 01/2019‐03/2021

“…Although being the first to describe an allergenic paramyosin in molluscs, this study included a small number of subjects and did not use any functional test to confirm this allergen's clinical relevance. 13 Several allergens with enzymatic activity were recently discovered from animal food sources. Fructose-bisphosphate aldolase class I (aldolase A) and beta-enolases are known fish allergen.…”

“…Yu et al identified Rap v 2, a paramyosin from veined rapa whelk, a sea snail, as an allergen and reduction in its IgE‐binding was demonstrated upon heating. Although being the first to describe an allergenic paramyosin in molluscs, this study included a small number of subjects and did not use any functional test to confirm this allergen's clinical relevance 13 …”