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Crystal and solution structures of an odorant-binding protein from the southern house mosquito complexed with an oviposition pheromone.

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.

SUBMITTER: Mao Y

PROVIDER: S-EPMC2973904 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Crystal and solution structures of an odorant-binding protein from the southern house mosquito complexed with an oviposition pheromone.

Mao Yang Y Xu Xianzhong X Xu Wei W Ishida Yuko Y Leal Walter S WS Ames James B JB Clardy Jon J

Proceedings of the National Academy of Sciences of the United States of America 20101018 44

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 cr ...[more]

PMID: 20956299

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Project description:Olfactory-based behaviors in mosquitoes are mediated by odorant-binding proteins (OBPs). They form a multigenic family involved in the peripheral events in insect olfaction, specifically the transport of odorants to membrane-bound odorant receptors. OBPs contribute to the remarkable sensitivity of the insect's olfactory system and may be involved in the selective transport of odorants.We have employed a combination of bioinformatics and molecular approaches to identify and characterize members of the "classic" OBP family in the Southern House mosquito Culex pipiens quinquefasciatus ( = Cx. quinquefasciatus), a vector of pathogens causing several human diseases. By taking advantage of the recently released genome sequences, we have identified fifty-three putative Cx. quinquefasciatus OBP genes by Blast searches. As a first step towards their molecular characterization, expression patterns by RT-PCR revealed thirteen genes that were detected exclusively and abundantly in chemosensory tissues. No clear differences were observed in the transcripts levels of olfactory-specific OBPs between antennae of both sexes using semi-quantitative RT-PCR. Phylogenetic and comparative analysis revealed orthologous of Cx. quinquefasciatus OBPs in Anopheles gambiae and Aedes aegypti. The identification of fifty-three putative OBP genes in Cx. quinquefasciatus highlights the diversity of this family. Tissue-specificity study suggests the existence of different functional classes within the mosquito OBP family. Most genes were detected in chemosensory as well as non chemosensory tissues indicating that they might be encapsulins, but not necessarily olfactory proteins. On the other hand, thirteen "true" OBP genes were detected exclusively in olfactory tissues and might be involved specifically in the detection of "key" semiochemicals. Interestingly, in Cx. quinquefasciatus olfactory-specific OBPs belong exclusively to four distinct phylogenetic groups which are particularly well conserved among three mosquito species.

Dataset Information

Crystal and solution structures of an odorant-binding protein from the southern house mosquito complexed with an oviposition pheromone.

Publications

Crystal and solution structures of an odorant-binding protein from the southern house mosquito complexed with an oviposition pheromone.

Similar Datasets

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