title: Binding properties of pheromone-binding protein 1 from the common cutworm Spodoptera litura.
abstract: Pheromone-binding proteins (PBPs) were formerly thought to act as passive pheromone carriers. However, recent studies, particularly in Drosophila melanogaster, suggest that PBPs are involved in the recognition of semiochemicals, thus making ligand-binding studies more meaningful. Previously, we cloned three PBPs from Spodoptera litura (Slit), and showed that SlitPBP1 is much more abundant than the other two, particularly in male antennae. To investigate the ligand specificity of SlitPBP1, we expressed the protein in a bacterial system and performed binding experiments with the three components of the specific sex pheromones (Z9-14:Ac, Z9,E11-14:Ac and Z9,E12-14:Ac), as well as with 26 volatile ligands. The results indicated that SlitPBP1 bound all three sex pheromone components with dissociation constants between 0.6 and 1.1 μM. The same protein also bound with comparable affinities several pheromone analogs, but not plant volatiles. The presence of a double bond was the most important element for a strong binding, while its position and configuration also affected the affinity. Finally, the binding of pheromone components is strongly affected by pH, showing a critical pH value corresponding to isoelectric point of the protein. This suggests that a pH-dependent conformational mechanism might exist in SlitPBP1 for pheromone binding and release.
authors.affiliation: Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Nai-Yong
authors.initials: NY
authors.lastname: Liu
authors.forename: Peng
authors.initials: P
authors.lastname: He
authors.forename: Shuang-Lin
authors.initials: SL
authors.lastname: Dong
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000378:metabolism*; D007526:Isoelectric Point; D008958:Models, Molecular; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011487:Protein Conformation; D012724:Sex Attractants / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D018411:Spodoptera / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D019476:Insect Proteins; D012724:Sex Attractants