Crystal structure and epitope analysis of house dust mite allergen Der f 21
Crystal structure and epitope analysis of house dust mite allergen Der f 21
复制标题
DOI：
10.1038/s41598-019-40879-x
复制
发表时间：
2019-03-20
影响因子：
4.6
通讯作者：
Ng, Chyan Leong
中科院分区：
文献类型：
--
作者：
Pang, Sze Lei;Ho, Kok Lian;Ng, Chyan Leong
第21组和第5组过敏原是被称为中级过敏原的同源屋尘螨蛋白质。为揭示21族变应原的生物学功能，进一步了解粉尘螨rDer f 21变应原的致敏性，测定了粉尘螨rDer f 21变应原的1.5A晶体结构。rDer f 21蛋白由三螺旋束组成，类似于第21组和同源第5组过敏原的可用结构。rDer f 21二聚体形成了一个与Der p 5过敏原中的疏水结合口袋类似的疏水结合口袋，这表明两个同源基团可能具有相似的功能。通过进行结构指导突变，我们对rDer f 21过敏原的所有38个表面暴露的极性残基进行了突变，并使用24种特应性血清进行了免疫斑点印迹分析。位于rDer f 21 N端与第1环之间的6个残基K10、K26、K42、E43、K46和K48被鉴定为rDer f 21的主要IgE表位。rDer f 21晶体结构表面上所有潜在IgE表位的表位作图揭示了特应性个体中过敏原表位的sIgE识别的异质性。个体的过敏原-sIgE水平越高，在过敏原中发现的表位残基的数量越高。结果表明，过敏原中特异性主要表位残基的数量与特应性人群的sIgE水平之间存在明确的相关性。
Group 21 and 5 allergens are homologous house dust mite proteins known as mid-tier allergens. To reveal the biological function of group 21 allergens and to understand better the allergenicity of the rDer f 21 allergen, we determined the 1.5 A crystal structure of rDer f 21 allergen from Dermatophagoides farinae. The rDer f 21 protein consists of a three helical bundle, similar to available structures of group 21 and homologous group 5 allergens. The rDer f 21 dimer forms a hydrophobic binding pocket similar to the one in the Der p 5 allergen, which indicates that both of the homologous groups could share a similar function. By performing structure-guided mutagenesis, we mutated all 38 surface-exposed polar residues of the rDer f 21 allergen and carried out immuno-dot blot assays using 24 atopic sera. Six residues, K10, K26, K42, E43, K46, and K48, which are located in the region between the N-terminus and the loop 1 of rDer f 21 were identified as the major IgE epitopes of rDer f 21. Epitope mapping of all potential IgE epitopes on the surface of the rDer f 21 crystal structure revealed heterogeneity in the sIgE recognition of the allergen epitopes in atopic individuals. The higher the allergen-sIgE level of an individual, the higher the number of epitope residues that are found in the allergen. The results illustrate the clear correlation between the number of specific major epitope residues in an allergen and the sIgE level of the atopic population.