Journal article
Extrusion of the C-terminal helix in navel orangeworm moth pheromone-binding protein (AtraPBP1) controls pheromone binding
Biochemical and Biophysical Research Communications, Vol.404(1), pp.335-338
2011
Abstract
The navel orangeworm, Amyelois transitella (Walker), is an agricultural insect pest that can be controlled by disrupting male–female communication with sex pheromones, a technique known as mating disruption. Insect pheromone-binding proteins (PBPs) provide fast transport of hydrophobic pheromones through aqueous sensillar lymph and promote sensitive delivery of pheromones to receptors. Here we present a mutational analysis on a PBP from A. transitella (AtraPBP1) to evaluate how the C-terminal helix in this protein controls pheromone binding as a function of pH. Pheromone binds tightly to AtraPBP1 at neutral pH, but the binding is much weaker at pH below 5. Deletion of the entire C-terminal helix (residues 129–142) causes more than 100-fold increase in pheromone-binding affinity at pH 5 and only a 1.5-fold increase at pH 7. A similar pH-dependent increase in pheromone binding is also seen for the H80A/H95A double mutant that promotes extrusion of the C-terminal helix by disabling salt bridges at each end of the helix. The single mutants (H80A and H95A) also exhibit pheromone binding at pH below 5, but with ∼2-fold weaker affinity. NMR and circular dichroism data demonstrate a large overall structural change in each of these mutants at pH 4.5, indicating an extrusion of the C-terminal helix that profoundly affects the overall structure of the low pH form. Our results confirm that sequestration of the C-terminal helix at low pH as seen in the recent NMR structure may serve to block pheromone binding. We propose that extrusion of these C-terminal residues at neutral pH (or by the mutations in this study) exposes a hydrophobic cleft that promotes high affinity pheromone binding.
Details
- Title
- Extrusion of the C-terminal helix in navel orangeworm moth pheromone-binding protein (AtraPBP1) controls pheromone binding
- Authors/Creators
- W. Xu (Author/Creator)X. Xu (Author/Creator)W.S. Leal (Author/Creator)J.B. Ames (Author/Creator)
- Publication Details
- Biochemical and Biophysical Research Communications, Vol.404(1), pp.335-338
- Publisher
- Academic Press
- Identifiers
- 991005541761707891
- Copyright
- © 2010 Elsevier Inc.
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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- 3 Agriculture, Environment & Ecology
- 3.220 Smell & Taste Science
- 3.220.701 Olfactory Systems
- Web Of Science research areas
- Biochemistry & Molecular Biology
- Biophysics
- ESI research areas
- Biology & Biochemistry