Structural characterization of the Pet c 1.0201 PR-10 protein isolated from roots of Petroselinum crispum (Mill.) Fuss.

The native dimeric Petroselinum crispum (Mill.) Fuss protein Pet c 1.0201 and a monomeric xyloglucan endotransglycosylase enzyme (Garajova et al., 2008) isolated from the root cells co-purify and share similar molecular masses and acidic isoelectric points. In this work, we determined the complete primary structure of the parsley Pet c 1.0201 protein, based on tryptic and chymotryptic peptides followed by the manual micro-gradient chromatographic separation coupled with offline MALDI-TOF/TOF mass spectrometry. The bioinformatics approach enabled us to include the parsley protein into the PR-10 family, as it exhibited the highest protein sequence identity with the Apium graveolens Api g 1.0201 allergen and the major Daucus carota allergen Dau c 1.0201. Hence, we designated the Petroselinum crispum protein as Pet c 1.0201 and deposited it in the UniProt Knowledgebase under the accession C0HKF5. 3D protein homology modelling and molecular dynamics simulations of the Pet c 1.0201 dimer confirmed the typical structure of the Bet v 1 family allergens, and the potential of the Pet c 1.0201 protein to dimerize in water. However, the behavioural properties of Pet c 1.0201 and the celery allergen Api g 1.0101 differed in the presence of salts due to transiently and stably formed dimeric forms of Pet c 1.0201 and Api g 1.0101, respectively.