Sequence analysis and expression of a cDNA clone encoding tropomysin in Sinonovacula constricta.

Shellfish can cause severe anaphylactic reactions. Tropomyosin has been assumed partly responsible for the cross-reactivity among shellfish and other invertebrates. In this study, cDNA of Sinonovacula constricta was amplified by RT-PCR and 3'-RACE from total RNA. The obtained tropomyosin cDNA included an open reading frame coding for 284 amino acids. The deduced amino acid sequence of the corresponding protein shared high identity with other allergenic tropomyosins. Expression of the recombinant tropomyosin was carried out in Escherichia coli BL21(DE3) using vector PET28a and the purification of the recombinant protein was performed via affinity chromatography. IgE reactivity of recombinant tropomyosin was investigated by immunoblot and the sensized precentage was 36% which indicated that tropomyosin was the minor allergens in S. constricta. Moreover, the character of the purified protein was analyzed by MALDI-TOF-MS.