Three-dimensional structure and IgE-binding properties of mature fully active Der p 1, a clinically relevant major allergen.
BACKGROUND
Der p 1 is a 25-kd allergen with cysteine protease activity. Sensitization to Der p 1 affects a large proportion of individuals with allergy, resulting in rhinitis, asthma, and/or atopic dermatitis.


OBJECTIVE
We determined the Der p 1 crystallographic structure to understand the relationships among structure, function, and allergenicity.


METHODS
Recombinant pro-Der p 1 was produced in Pichia pastoris and allowed to mature spontaneously before purification by a 2-step procedure. Protease activity was checked by using a fluorogenic peptide substrate. Allergenicity was analysed by IgE binding assays and basophil activation test. The determination of the 3-dimensional structure was obtained by X-ray crystallography at 1.9 A resolution.


RESULTS
The recombinant protein is fully active and expresses an allergenicity equivalent to its natural counterpart. Der p 1 exhibits a cysteine protease fold typical of the papain family, has a magnesium binding site, and forms dimers with a large interface. The crystal lattice shows that the dimers are tightly packed in a compact double layer of proteins. Such an assembly likely exists in dry fecal pellets, the natural form of allergen exposure, and appears ideal to interact with cell surface and trigger allergic inflammation.


CONCLUSIONS
We present here the 3-dimensional structural features of mature fully active Der p 1, one of the main allergens involved in human allergic diseases. This opens the possibility to evaluate the importance of enzymatic activity in pathology and possible new therapeutic interventions.
de Halleux
Sonia
S
Center for Molecular and Vascular Biology, University of Leuven, Belgium.
Stura
Enrico
E
VanderElst
Luc
L
Carlier
Vincent
V
Jacquemin
Marc
M
Saint-Remy
Jean-Marie
JM
D000485:Allergens / Q000096:biosynthesis / Q000276:immunology* / Q000648:ultrastructure*; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000096:biosynthesis / Q000276:immunology* / Q000648:ultrastructure*; D060829:Arthropod Proteins; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D010843:Pichia; D011485:Protein Binding; D011487:Protein Conformation; D039981:Pyroglyphidae / Q000276:immunology; D011994:Recombinant Proteins / Q000096:biosynthesis; D013329:Structure-Activity Relationship
D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D003546:Cysteine Endopeptidases; C451162:Dermatophagoides pteronyssinus antigen p 1