Identification of serine protease as a major allergen of Curvularia lunata.
BACKGROUND
Several proteins from Curvularia lunata have been identified as important fungal allergens. It will be worthwhile to study the functional aspects of these allergens. The present study aimed at purifying a major allergen and determining its biological function.


METHODS
Concanavalin A and Superdex 75 were used to purify Cur l 1 major allergen from C. lunata. Cur l 1 activity was determined qualitatively and quantitatively. Serine protease inhibitors and specific substrate was used to determine the biological function of the protein.


RESULTS
Concanavalin A-bound fraction showed five allergenic proteins, which on Superdex G-75 purification gave a homogenous Cur l 1 protein. Cur l 1 showed IgE reactivity with 80% of the C. lunata hypersensitive patient's sera indicating it to be a major allergen. It showed protease activity on different substrates. Cur l 1's amino terminal sequence, GLTQKSAPWGLGADTIVAVELDSY, showed homology with the alkaline serine protease precursor. Phenylmethylsulfonylfluoride, pefabloc, aprotinin and leupeptin inhibited 70-80% enzymatic activity of Cur l 1 and no inhibition was observed with ethylenediaminetetraacetic acid (EDTA). A dose-dependent hydrolysis of Nalpha-benzoyl-l-arginine ethyl ester-hydrochloride, a specific serine protease substrate was obtained with Cur l 1.


CONCLUSIONS
A major glycoprotein allergen Cur l 1 was purified to homogeneity from C. lunata. Amino terminal sequence and biochemical assays identified it as a serine protease.
Institute of Genomics and Integrative Biology, Delhi, India.
R
R
Gupta
V
V
Sharma
S
S
Sridhara
B P
BP
Singh
N
N
Arora
D000485:Allergens / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D007073:Immunoglobulin E / Q000378:metabolism; D003904:Mitosporic Fungi / Q000276:immunology*; D008969:Molecular Sequence Data; D012697:Serine Endopeptidases / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*
D000485:Allergens; D007073:Immunoglobulin E; D012697:Serine Endopeptidases