title: Coil-to-helix transition and ligand release of Bombyx mori pheromone-binding protein.
abstract: The transport of hydrophobic insect pheromones through the aqueous medium surrounding their receptors is assisted by pheromone-binding proteins (PBPs). The protein from the silkworm moth Bombyx mori, BmorPBP, exhibits a pH-dependent conformational change postulated to trigger the release of the pheromone bombykol to its receptor. At low pH, an alpha-helix occupies the same binding pocket that houses the pheromone in the BmorPBP-bombykol complex at high pH. We have determined the crystal structure of apo BmorPBP at a resolution of 2.3 angstroms and pH 7.5, which has surprisingly a structure similar to the A-form. These data suggest that BmorPBP undergoes a ligand-dependent conformational change in addition to the previously described pH-dependent conformational change. Analysis of the alpha-helix occupying the binding pocket reveals an amphipathic helix with three acidic residues along one face that are conserved among lepidopteran PBPs and may be involved in a conformational transition of BmorPBP at the receptor membrane.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lautenschlager
authors.forename: Walter S
authors.initials: WS
authors.lastname: Leal
authors.forename: Jon
authors.initials: J
authors.lastname: Clardy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D012831:Bombyx / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis* / Q000737:chemistry*; D003198:Computer Simulation; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000032:analysis* / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009038:Motion; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
chemical_list: D002352:Carrier Proteins; D019476:Insect Proteins; D008024:Ligands; C403713:pheromone binding protein, insect