Identification of non-specific Lipid Transfer Protein gene family members in Solanum lycopersicum and insights into the features of Sola l 3 protein

Non-specific lipid transfer proteins (nsLTPs) are characterized by an eight-cysteine motif backbone that is stabilized by four disulphide bonds. The strong interest towards this protein family is mainly due to the fact that nsLTPs are involved in many biological processes and have been identified as major human allergens. Since tomato (Solanum lycopersicum L.) is one of the most consumed and allergenic vegetables, a full characterization of this family is needed. In this study, hidden Markov model profiles were used to identify nsLTPs within the tomato protein complement. Following manual curation, 64 nsLTP genes were classified into six sub-families. Furthermore, nsLTP gene structure, distribution and arrangement along tomato chromosomes were investigated. Available RNA-seq expression profile data and Real-Time PCR analyses were used to derive expression patterns of tomato nsLTPs in different tissues/organs. Non-specific LTP genes with high level of expression in tomato fruits were filtered out since they could play a key role in tomato allergenicity. Among these genes was Solyc10g075090 that encodes the allergen Sola l 3. Finally, cloning, heterologous expression, purification and biochemical characterization of the recombinant protein Sola l 3 was performed.