Computational analysis of thaumatin-II allergenicity and prediction of antigenic elements of thaumatin-like family proteins

Abstract

Thaumatin-II is an intense sweet tasting protein isolated from fruits of Thaumatococcus daniellii. Thaumatin is a member of the pathogenesis-related protein family referred to as thaumatinlike proteins (TLPs). Expression of thaumatin-II in plants was associated with an enhanced resistance against pathogens. In addition, thaumatin was used to provide the sweet taste quality to plant products. Thus, TLP proteins have a potential application for improving plant stress resistance and taste qualities using the recombinant DNA technology. However, several members of the TLP family were characterized as food allergens. The allergenic properties of thaumatin-II have not been characterized. In this study, a putative allergenicity of thaumatin-II was established using computational analysis of sequence similarity with known human allergens. Antigenicity analysis and multiple sequence alignment of related TLP sequences identified six putative allergenic epitopes. The residues Thr12, Leu74, Gln133 and Thr161 of thaumatin-II or equivalent residues of other TLPs were proposed as a target for mutagenesis aimed to develop protein isoforms with reduced allergenicity. Keywords: thaumatin-II, thaumatin-like proteins, allergenicity, antigenicity, computational analysis