Pheromone binding to general odorant-binding proteins from the navel orangeworm

Area of Science:

• Insect olfaction
• Molecular biology
• Biochemistry

Background:

• General odorant-binding proteins (GOBPs) are hypothesized to detect non-pheromone semiochemicals in moths.
• Two GOBPs, AtraGOBP1 and AtraGOBP2, were isolated from the antennae of the navel orangeworm, Amyelois transitella.

Purpose of the Study:

• To investigate the binding properties of recombinant AtraGOBP1 and AtraGOBP2.
• To determine if these GOBPs interact with known moth attractants or pheromones.

Main Methods:

• Recombinant expression and purification of AtraGOBP1 and AtraGOBP2.
• Circular dichroism analysis to confirm protein folding.
• Ligand binding assays to assess interactions with various odorants.
• Electroantennography (EAG) to measure antennal sensitivity to attractants and pheromones.

Main Results:

• AtraGOBP1 and AtraGOBP2 did not bind known female attractants.
• Both GOBPs exhibited pH-dependent binding of nonanal.
• AtraGOBP2 showed significant binding affinity for the sex pheromone component Z11Z13-16Ald.
• Antennal sensitivity to female attractants and male pheromones decreased with moth age.

Conclusions:

• The function of AtraGOBP1 and AtraGOBP2 in detecting general odorants remains uncertain.
• AtraGOBP2 may play a role in pheromone reception, challenging the traditional view of GOBP function.
• Age-dependent changes in antennal sensitivity suggest developmental regulation of olfactory responses.