title: Structure-activity studies with pheromone-binding proteins of the gypsy moth, Lymantria dispar.
abstract: Pheromone olfaction in the gypsy moth, Lymantria dispar, involves accurate distinction of compounds with similar structure and polarity. The identified sex pheromone is (7R,8S)-2-methyl-7,8-epoxyoctadecane, 1a, and a known antagonist is (7Z)-2-methyloctadec-7-ene, 4a. The first step in pheromone olfaction is binding of odorants by small, soluble pheromone-binding proteins (PBPs), found in the pheromone-sensing hairs. We have studied the molecular determinants recognized by the two PBPs found in the gypsy moth, using three pheromone/PBP binding assays. Results indicate that (i) PBPs bind analogs of the pheromone with some discrimination; (ii) PBPs experience enhancement of binding when presented with 1a or its enantiomer and 4a simultaneously; and (iii) the binding enhancement is also seen at high ligand:PBP ratios. We found no evidence of allostery, so the synergistic binding effects and the concentration effect may only be explained by multimerization of PBPs with each other, which leads to more than one population of binding sites. We suggest that the enhanced ligand binding at high ligand:PBP ratios may serve to sequester excess ligand and thereby attenuate very strong signals.
authors.affiliation: Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby BC, Canada V5A 1S6.
authors.forename: Nicolette
authors.initials: N
authors.lastname: Honson
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Johnson
authors.forename: James E
authors.initials: JE
authors.lastname: Oliver
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Prestwich
authors.forename: Erika
authors.initials: E
authors.lastname: Plettner
mesh_terms: D000473:Alkanes / Q000737:chemistry / Q000378:metabolism; D000475:Alkenes / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D019476:Insect Proteins / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D009036:Moths / Q000378:metabolism* / Q000502:physiology; D011869:Radioligand Assay; D012724:Sex Attractants / Q000737:chemistry / Q000378:metabolism*; D012903:Smell; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: C466019:2-methyl-7-octadecene; D000473:Alkanes; D000475:Alkenes; D002352:Carrier Proteins; D019476:Insect Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; C111001:PBP1 protein, Lymantria dispar; C111000:PBP2 protein, Lymantria dispar; D012724:Sex Attractants; C001150:disparlure