| Title: | Crystal structure of Sol I 2: a major allergen from fire ant venom |
| Author(s): | Borer AS; Wassmann P; Schmidt M; Hoffman DR; Zhou JJ; Wright C; Schirmer T; Markovic-Housley Z; |
| Address: | "Department of Structural Biology, Biozentrum, University of Basel, Basel, Switzerland" |
| DOI: | 10.1016/j.jmb.2011.10.009 |
| ISSN/ISBN: | 1089-8638 (Electronic) 0022-2836 (Linking) |
| Abstract: | "Sol i 2 is a potent allergen from the venom of red imported fire ant, which contains allergens Sol i 1, Sol i 2, Sol i 3, and Sol i 4 that are known to be powerful triggers of anaphylaxis. Sol i 2 causes IgE antibody production in about one-third of individuals stung by fire ants. Baculovirus recombinant dimeric Sol i 2 was crystallized as a native and selenomethionyl-derivatized protein, and its structure has been determined by single-wavelength anomalous dispersion at 2.6 A resolution. The overall fold of each subunit consists of five helices that enclose a central hydrophobic cavity. The structure is stabilized by three intramolecular disulfide bridges and one intermolecular disulfide bridge. The nearest structural homologue is the sequence-unrelated odorant binding protein and pheromone binding protein LUSH of the fruit fly Drosophila, which may suggest a similar biological function. To test this hypothesis, we measured the reversible binding of various pheromones, plant odorants, and other ligands to Sol i 2 by the changes in N-phenyl-1-naphthylamine fluorescence emission upon binding of ligands that compete with N-phenyl-1-naphthylamine. The highest binding affinity was observed for hydrophobic ligands such as aphid alarm pheromone (E)-beta-farnesene, analogs of ant alarm pheromones, and plant volatiles decane, undecane, and beta-caryophyllene. Conceivably, Sol i 2 may play a role in capturing and/or transporting small hydrophobic ligands such as pheromones, odors, fatty acids, or short-living hydrophobic primers. Molecular surface analysis, in combination with sequence alignment, can explain the serological cross-reactivity observed between some ant species" |
| Keywords: | "Allergens/*chemistry/metabolism Amino Acid Sequence Animals Ant Venoms/*chemistry/immunology/metabolism Binding Sites Binding, Competitive Crystallography, X-Ray Insect Proteins/*chemistry/metabolism Ligands Models, Biological Models, Molecular Molecular;" |
| Notes: | "MedlineBorer, Aline S Wassmann, Paul Schmidt, Margit Hoffman, Donald R Zhou, Jing-Jiang Wright, Christine Schirmer, Tilman Markovic-Housley, Zora eng Research Support, Non-U.S. Gov't Netherlands 2011/11/22 J Mol Biol. 2012 Jan 27; 415(4):635-48. doi: 10.1016/j.jmb.2011.10.009. Epub 2011 Nov 12" |
