Correlating Low-Similarity Peptide Sequences and Allergenic Epitopes

Abstract

Although a high number of allergenic peptide epitopes has been experimentally identified and defined, the molecular basis and the precise mechanisms underlying peptide allergenicity are unknown. This issue was analyzed exploring the relationship between peptide allergenicity and sequence similarity to the human proteome. The structured analysis of the data reported in literature put into evidence that the most part of IgE-binding epitopes are (or harbor) pentapeptide unit(s) with no/low similarity to the human proteome, this way suggesting that no or low sequence similarity to the host proteome might represent a minimum common denominator identifying allergenic peptides. The present literature analysis might be of relevance in devising and designing short amino acid modules to be used for blocking pathogenic IgE.

The self/nonself issue: A confrontation between proteomes

“…The data add to and support experimental results from our laboratory [21][22][23][24][25][26][27]31 and reported meta-analyses. [28][29][30] Theoretically, proteomic similarity analyses might elucidate the regulatory mechanisms/factors that dictate peptide immunogenicity assessment. From a clinical perspective, low-similarity peptides may have strong repercussions affecting the rational development of peptide-based treatments in cancer, infection and autoimmunity.…”

The Occurrence of Sequences Identical with Epitopes from the Allergen Pen a 1.0102 Among Food and Non-Food Proteins

“…Pentapeptides as fragments of epitopes interacting with IgE and originating from various allergens have previously been found in human protein sequences [Kanduc, 2008]. The fragments of tropomyosin from Farfantepenaeus aztecus were among them.…”

“…Rare pentapeptides are considered as basic motifs responsible for stimulation of the immune system [Kanduc, 2008[Kanduc, , 2012. Pentapeptide may be considered as rare if it only occurs in hundreds of protein sequences.…”

“…The presence of a local sequence identity suggests potential cross-reactions between proteins [Kleter & Peijnenburg, 2002;Marti et al, 2007;Kanduc, 2008;2012;Minkiewicz et al, 2011]. Examples of invertebrate tropomyosins with common epitopes can be found in the BIOPEP database of allergenic proteins [Dziuba et al, 2013].…”

“…In further studies [Minkiewicz et al, 2011;2012] protein fragments possessing 100% identity with entire epitopes were considered. Pentapeptides are the shortest fragments recognised by the immune system [Kanduc, 2008]. The existence of a common fragment containing at least 6-8 amino acid residues is a recommended bioinformatics criterion defi ning protein as an allergen cross-reacting with previously-known allergenic proteins [Goodman, 2006].…”