ORCID Profile
0000-0002-6800-1240
Current Organisation
University of California Davis
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Publisher: Springer Science and Business Media LLC
Date: 26-06-2009
Publisher: Proceedings of the National Academy of Sciences
Date: 18-10-2010
Abstract: Culex mosquitoes introduce the pathogens responsible for filariasis, West Nile virus, St. Louis encephalitis, and other diseases into humans. Currently, traps baited with oviposition semiochemicals play an important role in detection efforts and could provide an environmentally friendly approach to controlling their populations. The odorant binding proteins (OBPs) in the female's antenna play a crucial, if yet imperfectly understood, role in sensing oviposition cues. Here, we report the X-ray crystallography and NMR 3D structures of OBP1 for Culex quinquefasciatus (CquiOBP1) bound to an oviposition pheromone ( 5R,6S )-6-acetoxy-5-hexadecanolide (MOP). In both studies, CquiOBP1 had the same overall six-helix structure seen in other insect OBPs, but a detailed analysis revealed an important previously undescribed feature. There are two models for OBP-mediated signal transduction: ( i ) direct release of the pheromone from an internal binding pocket in a pH-dependent fashion and ( ii ) detection of a pheromone-induced conformational change in the OBP·pheromone complex. Although CquiOBP1 binds MOP in a pH-dependent fashion, it lacks the C terminus required for the pH-dependent release model. This study shows that CquiOBP binds MOP in an unprecedented fashion using both a small central cavity for the lactone head group and a long hydrophobic channel for its tail.
Publisher: American Chemical Society (ACS)
Date: 29-01-2010
DOI: 10.1021/BI9020132
Publisher: Public Library of Science (PLoS)
Date: 22-10-2010
Publisher: Public Library of Science (PLoS)
Date: 22-08-2008
Publisher: Public Library of Science (PLoS)
Date: 26-11-2009
Publisher: Public Library of Science (PLoS)
Date: 30-09-2009
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.STR.2006.08.013
Abstract: Pheromone-binding proteins are postulated to contribute to the exquisite specificity of the insect's olfactory system, acting as a filter by preferentially binding only one of the components of the natural pheromone. Here, we investigated the possible discrimination of the two very similar components of the natural pheromone gland from the silk moth, Bombyx mori, bombykol and bombykal, by the only pheromone-binding protein (BmorPBP) known to be expressed in the pheromone-detecting sensilla. Free-energy calculations and virtual docking indicate that both bombykol and bombykal bind to BmorPBP with similar affinity. In addition, in vitro competitive binding assays showed that both bombykol and bombykal were bound by BmorPBP with nearly the same high affinity. While BmorPBP might filter out other physiologically irrelevant compounds hitting the sensillar lymph, discrimination between the natural pheromone compounds must be achieved by molecular interactions with their cognate receptors.
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.BBRC.2008.05.087
Abstract: Pheromone-binding proteins (PBPs) are involved in the uptake of pheromones from pores on the antennae, transport through an aqueous environment surrounding the olfactory receptor neurons, and fast delivery to pheromone receptors. We tested the hypothesis that a C-terminal segment and a flexible loop are involved in the release of pheromones to membrane-bound receptors. We expressed in Escherichia coli 11 mutants of the PBP from the silkworm moth, BmorPBP, taking into consideration structural differences between the forms with high and low binding affinity. The N-terminus was truncated and His-69, His-70 and His-95 at the base of a flexible loop, and a cluster of acidic residues at the C-terminus were mutated. Binding assays and circular dichroism analyses support a mechanism involving protonation of acidic residues Asp-132 and Glu-141 at the C-terminus and histidines, His-70 and His-95, in the base of a loop covering the binding pocket. The former leads to the formation of a new alpha-helix, which competes with pheromone for the binding pocket, whereas positive charge repulsion of the histidines opens the opposite side of the binding pocket.
No related grants have been discovered for Walter Leal.