Laboratory of Structural Biology, National Institute of Environmental Health Sciences, Research Triangle Park, NC.
J Allergy Clin Immunol. 2013 Dec;132(6):1420-6. doi: 10.1016/j.jaci.2013.06.014. Epub 2013 Jul 31.
Sensitization to cockroach allergens is a major risk factor for asthma. The cockroach allergen Bla g 1 has multiple repeats of approximately 100 amino acids, but the fold of the protein and its biological function are unknown.
We sought to determine the structure of Bla g 1, investigate the implications for allergic disease, and standardize cockroach exposure assays.
nBla g 1 and recombinant constructs were compared by using ELISA with specific murine IgG and human IgE. The structure of Bla g 1 was determined by x-ray crystallography. Mass spectrometry and nuclear magnetic resonance spectroscopy were used to examine the ligand-binding properties of the allergen.
The structure of an rBla g 1 construct with comparable IgE and IgG reactivity to the natural allergen was solved by x-ray crystallography. The Bla g 1 repeat forms a novel fold with 6 helices. Two repeats encapsulate a large and nearly spherical hydrophobic cavity, defining the basic structural unit. Lipids in the cavity varied depending on the allergen origin. Palmitic, oleic, and stearic acids were associated with nBla g 1 from cockroach frass. One unit of Bla g 1 was equivalent to 104 ng of allergen.
Bla g 1 has a novel fold with a capacity to bind various lipids, which suggests a digestive function associated with nonspecific transport of lipid molecules in cockroaches. Defining the basic structural unit of Bla g 1 facilitates the standardization of assays in absolute units for the assessment of environmental allergen exposure.
对蟑螂过敏原的致敏是哮喘的一个主要危险因素。蟑螂过敏原 Bla g 1 含有多个约 100 个氨基酸的重复序列，但该蛋白质的折叠及其生物学功能尚不清楚。
我们旨在确定 Bla g 1 的结构，探讨其对过敏性疾病的影响，并标准化蟑螂暴露测定。
通过 ELISA 比较 nBla g 1 和重组构建体与特异性鼠 IgG 和人 IgE 的反应。通过 X 射线晶体学确定 Bla g 1 的结构。质谱和核磁共振波谱用于研究过敏原的配体结合特性。
通过 X 射线晶体学解决了具有与天然过敏原相当的 IgE 和 IgG 反应性的 rBla g 1 构建体的结构。Bla g 1 重复形成具有 6 个螺旋的新型折叠。两个重复包封一个大的几乎球形的疏水性腔，定义了基本的结构单元。腔内的脂质因过敏原来源而异。棕榈酸、油酸和硬脂酸与来自蟑螂粪便的 nBla g 1 相关。一个 Bla g 1 单位相当于 104ng 过敏原。
Bla g 1 具有一种新型折叠，能够结合各种脂质，这表明它具有与蟑螂中非特异性脂质分子转运相关的消化功能。定义 Bla g 1 的基本结构单元有助于以绝对单位标准化测定，以评估环境过敏原暴露。
