Identification and in silico bioinformatics analysis of PR10 proteins in cashew nut.

Shanna Bastiaan‐Net,Antoine H P America,Renata M C Ariëns,Maria C Pina‐Pérez,Harry J Wichers,Bas J W Dekkers,Jurriaan J Mes,Nicolette W De Jong,Adrie H Westphal

doi:10.1002/pro.3856

Abstract

Proteins from cashew nut can elicit mild to severe allergic reactions. Three allergenic proteins have already been identified, and it is expected that additional allergens are present in cashew nut. pathogenesis‐related protein 10 (PR10) allergens from pollen have been found to elicit similar allergic reactions as those from nuts and seeds. Therefore, we investigated the presence of PR10 genes in cashew nut. Using RNA‐seq analysis, we were able to identify several PR10‐like transcripts in cashew nut and clone six putative PR10 genes. In addition, PR10 protein expression in raw cashew nuts was confirmed by immunoblotting and liquid chromatography–mass spectrometry (LC–MS/MS) analyses. An in silico allergenicity assessment suggested that all identified cashew PR10 proteins are potentially allergenic and may represent three different isoallergens.

Highlights

The cashew tree (Anacardium occidentale L.) is a tropical perennial tree native to South America.[1]
Ara h 8, the Bet v 1-homolog in peanut, is most likely responsible for the cross-reactivity observed between birch and peanut and its associated oral allergy syndrome (OAS) symptoms,[24] while the protein 10 (PR10) protein Jug r 5 is associated with the manifestation of a birch pollenassociated walnut allergy.[25]
Two approaches have been applied to demonstrate the presence of PR10 proteins in cashew nut: immunoblotting using commercial IgG antibodies against Bet v 1 and Ara h 8 (PR10 protein from peanut35), and LC–MS/MS peptide identification using the identified cashew PR10 RNA-seq contig sequences as well as the cloned PR10 gene variances as database-query (Figure 5)

Summary

| INTRODUCTION

The cashew tree (Anacardium occidentale L.) is a tropical perennial tree native to South America.[1]. Bet v 1 from birch pollen is a main elicitor of pollen allergy symptoms and the first identified allergenic member of the family 10 of pathogenesis-related proteins (PR10).[21] Bet v 1 cross-reactive homolog that act as elicitors of a food-mediated OAS allergic immune response have been found in various fruits, vegetables, nuts (hazelnut, walnut, almond, and peanut) and seeds.[20,21,22,23] For instance, Ara h 8, the Bet v 1-homolog in peanut, is most likely responsible for the cross-reactivity observed between birch and peanut and its associated OAS symptoms,[24] while the PR10 protein Jug r 5 is associated with the manifestation of a birch pollenassociated walnut allergy.[25]. Subsequent cloning and sequence analysis enabled us to identify multiple PR10 genes in cashew nut and allowed us to perform an in silico prediction analysis for allergenic potency of the identified putative cashew PR10 proteins

| RESULTS

| DISCUSSION

Findings

| MATERIALS AND METHODS