| Title: | Extrusion of the C-terminal helix in navel orangeworm moth pheromone-binding protein (AtraPBP1) controls pheromone binding |
| Author(s): | Xu W; Xu X; Leal WS; Ames JB; |
| Address: | "Department of Entomology, University of California, Davis, CA 95616, USA" |
| Journal Title: | Biochem Biophys Res Commun |
| DOI: | 10.1016/j.bbrc.2010.11.119 |
| ISSN/ISBN: | 1090-2104 (Electronic) 0006-291X (Print) 0006-291X (Linking) |
| 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 approximately 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" |
| Keywords: | "Animals Carrier Proteins/*chemistry/genetics Circular Dichroism DNA Mutational Analysis Female Hydrogen-Ion Concentration Insect Proteins/*chemistry/genetics Male Moths/*metabolism Mutation Nuclear Magnetic Resonance, Biomolecular Pheromones/*chemistry Pr;" |
| Notes: | "MedlineXu, Wei Xu, Xianzhong Leal, Walter S Ames, James B eng R01 NS059969/NS/NINDS NIH HHS/ R01 NS059969-04/NS/NINDS NIH HHS/ R01 EY012347-14/EY/NEI NIH HHS/ R01 EY012347/EY/NEI NIH HHS/ EY012347/EY/NEI NIH HHS/ S10 RR011973/RR/NCRR NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2010/12/07 Biochem Biophys Res Commun. 2011 Jan 7; 404(1):335-8. doi: 10.1016/j.bbrc.2010.11.119. Epub 2010 Dec 3" |
