Identification of Proteases and Protease Inhibitors in Allergenic and Non-Allergenic Pollen

Abstract

Pollen is one of the most common causes of allergy worldwide, making the study of their molecular composition crucial for the advancement of allergy research. Despite substantial efforts in this field, it is not yet clear why some plant pollens strongly provoke allergies while others do not. However, proteases and protease inhibitors from allergen sources are known to play an important role in the development of pollen allergies. In this study, we aim to uncover differences in the transcriptional pattern of proteases and protease inhibitors in Betula verrucosa and Pinus sylvestris pollen as models for high and low allergenic potential, respectively. We applied RNA sequencing to Betula verrucosa and Pinus sylvestris pollen. After de-novo assembly we derived general functional profiles of the protein coding transcripts. By utilization of domain based functional annotation we identified potential proteases and protease inhibitors and compared their expression in the two types of pollen. Functional profiles are highly similar between Betula verrucosa and Pinus sylvestris pollen. Both pollen contain proteases and inhibitors from 53 and 7 Pfam families, respectively. Some of the members comprised within those families are implicated in facilitating allergen entry, while others are known allergens themselves. Our work revealed several candidate proteins which, with further investigation, represent exciting new leads in elucidating the process behind allergic sensitization.

Keywords: allergenicity; pollen transcriptome; protease; protease inhibitor.

Figure 1

Analysis workflow. Two strategies were implemented: (i) De-novo assembly and mapping the transcript to SwissProt sequences split into Pfam domains. (ii) Direct read mapping to the Arabidopsis thaliana reference proteome with subsequent Pfam based assessment. An example of a multi-domain protease is given by the cartoon of Der p 1, which includes a protease domain (green) and a propeptide domain (blue).