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J Allergy Clin Immunol. 2013 Dec;132(6):1420-6. doi: 10.1016/j.jaci.2013.06.014. Epub 2013 Jul 31.

The novel structure of the cockroach allergen Bla g 1 has implications for allergenicity and exposure assessment.

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Laboratory of Structural Biology, National Institute of Environmental Health Sciences, Research Triangle Park, NC. Electronic address:



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.


Allergen; Bla g 1; GFP; GST; Glutathione-S-transferase; Green fluorescent protein; MS; Mass spectrometry; NMR; NSP; Nitrile-specifier protein; Nuclear magnetic resonance spectroscopy; PC; PE; PG; PI; Phosphatidylcholine; Phosphatidylethanolamine; Phosphatidylglycerol; Phosphatidylinositol; Recombinant Bla g 1 expressed in Escherichia coli; Recombinant Bla g 1 expressed in Pichia pastoris; Recombinant Bla g 1 with an N-terminal GFP; TEV; TLR; Tobacco etch virus; Toll-like receptor; asthma; cockroach; exposure assessment; ligand-binding proteins; rBla g 1–EC; rBla g 1–GFP; rBla g 1–PP; structure

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