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Pheromone-binding proteins of scarab beetles
W S Leal1, H Wojtasek, M Miyazawa
1Laboratory of Chemical Prospecting, National Institute of Sericultural and Entomological Science, Tsukuba, Japan. leal@nises.affrc.go.jp
Annals of the New York Academy of Sciences
|February 27, 1999
Summary
Scarab beetle pheromone binding proteins (PBPs) can recognize both the attractant and repellent forms of japonilure. This suggests that PBPs may have broader ligand specificities than previously understood in insect chemical communication.
Area of Science:
- Insect biochemistry and molecular biology
- Chemical ecology and semiochemistry
- Evolutionary biology of insect communication
Background:
- Pheromone binding proteins (PBPs) are crucial for insect olfaction, particularly in detecting airborne chemical signals like pheromones.
- Scarab beetles, like Anomala osakana and Popillia japonica, rely on specific chemical cues for mating and other social behaviors.
- Japonilure, a key pheromone component in some scarab beetles, exists as enantiomers with distinct biological roles (attractant vs. antagonist).
Purpose of the Study:
- To characterize the pheromone binding proteins (PBPs) in the antennae of various scarab beetle species.
- To investigate the ligand-binding specificities of these PBPs, particularly concerning the enantiomers of japonilure.
- To compare PBP characteristics and binding capabilities across different insect taxa, including moths.
Main Methods:
- Biochemical characterization of PBPs isolated from scarab beetle antennae.
- Analysis of PBP expression patterns in both male and female beetles.
- Binding assays using purified Anomala osakana PBP and both japonilure enantiomers.
- Comparative analysis with known moth PBPs and their pheromone ligands.
Main Results:
- A single class of PBP was identified in most studied scarab beetle species, with homologous PBPs found in Anomala osakana and Popillia japonica.
- The PBP from Anomala osakana demonstrated binding to both japonilure enantiomers, which serve as attractant and antagonist signals.
- Binding affinity for both enantiomers by the Anomala osakana PBP was low, and surprisingly, moth PBPs also bound these ligands despite unrelated pheromone structures.
Conclusions:
- Scarab beetle PBPs exhibit a capacity to bind both attractant and antagonist enantiomers of japonilure, challenging previous assumptions.
- The observed low-affinity binding suggests a potentially less stringent ligand specificity for PBPs than widely postulated.
- Cross-species binding, even between distantly related insects like beetles and moths, indicates conserved or convergent PBP functions.