Identification of methionine synthase (Sal k 3), as a novel allergen of Salsola kali pollen.
Salsola kali pollen is a common cause of pollinosis during summer and early fall in desert and semi-desert regions. The aim of this study was the identification and characterization of Sal k 3, a new allergen from S. kali pollen. S. kali pollen extract was fractionated by SDS-PAGE and the allergenic profile was determined by IgE-immunoblotting using twelve S. kali allergic patients. Protein identification was carried out by the means of mass spectrometry. Using degenerated primers, two DNA fragments encoding N- and C-terminal domain of Sal k 3 were amplified by PCR, then cloned into the PTZ57R/T vector and sequenced. The open reading frame of Sal k 3 fragments were subcloned in the pET-32b(+) vector, expressed in E. coli, and purified by Ni2+ affinity chromatography. The IgE-binding capacity of rSal k 3 fragments was then studied by IgE-immunoblotting, inhibition assays, and skin prick tests. A 45-kDa allergen was identified as a fragment of the cobalamin-independent methionine synthase (MetE) by mass spectrometry and was detected in the sera of 8/12 (66.6%) of S. kali allergic patients. Moreover, inhibition assays demonstrated that the purified rSal k 3 fragments were similar to their counterparts in the crude extract. Sal k 3 represents a new allergen of S. kali pollen and seems to be an important allergenic compound in S. kali pollen.
Department of Immunology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. assarehzadeganma831@mums.ac.ir
Mohammad Ali
MA
Assarehzadegan
Mojtaba
M
Sankian
Farahzad
F
Jabbari
Mohsen
M
Tehrani
Reza
R
Falak
Abdolreza
A
Varasteh
D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate; D007073:Immunoglobulin E / Q000276:immunology; D008297:Male; D008780:Methyltransferases / Q000737:chemistry / Q000276:immunology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis / Q000737:chemistry; D010936:Plant Extracts / Q000276:immunology; D010940:Plant Proteins / Q000032:analysis / Q000737:chemistry; D011058:Pollen / Q000201:enzymology* / Q000276:immunology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification; D031248:Salsola / Q000201:enzymology* / Q000276:immunology*; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D040681:Structural Homology, Protein
D000485:Allergens; D010455:Peptides; D010936:Plant Extracts; D010940:Plant Proteins; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D008780:Methyltransferases; C022725:5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase