Molecular evolution of Odorant-binding proteins gene family in two closely related Anastrepha fruit flies

Abstract

BackgroundOdorant-binding proteins (OBPs) are of great importance for survival and reproduction since they participate in initial steps of the olfactory signal transduction cascade, solubilizing and transporting chemical signals to the olfactory receptors. A comparative analysis of OBPs between closely related species may help explain how these genes evolve and are maintained under natural selection and how differences in these proteins can affect olfactory responses. We studied OBP genes in the closely related species Anastrepha fraterculus and A. obliqua, which have different host preferences, using data from RNA-seq cDNA libraries of head and reproductive tissues from male and female adults, aiming to understand the speciation process occurred between them.ResultsWe identified 23 different OBP sequences from Anastrepha fraterculus and 24 from A. obliqua, which correspond to 20 Drosophila melanogaster OBP genes. Phylogenetic analysis separated Anastrepha OBPs sequences in four branches that represent four subfamilies: classic, minus-C, plus-C and dimer. Both species showed five plus-C members, which is the biggest number found in tephritids until now. We found evidence of positive selection in four genes and at least one duplication event that preceded the speciation of these two species. Inferences on tertiary structures of putative proteins from these genes revealed that at least one positively selected change involves the binding cavity (the odorant binding region) in the plus-C OBP50a.Conclusions A. fraterculus and A. obliqua have a bigger OBP repertoire than the other tephritids studied, though the total number of Anastrepha OBPs may be larger, since we studied only a limited number of tissues. The contrast of these closely related species reveals that there are several amino acid changes between the homologous genes, which might be related to their host preferences. The plus-C OBP that has one amino acid under positive selection located in the binding cavity may be under a selection pressure to recognize and bind a new odorant. The other positively selected sites found may be involved in important structural and functional changes, especially ones in which site-specific changes would radically change amino acid properties.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0775-0) contains supplementary material, which is available to authorized users.

Odorant Binding Proteins and Chemosensory Proteins in Episyrphus balteatus (Diptera: Syrphidae): Molecular Cloning, Expression Profiling, and Gene Evolution

“…Positive selection between putatively homologous copies was analyzed in two commonly predatory hoverflies, E. balteatus and E. corollae . Because OBPs share low sequence similarity, similar to what has been done in other insects ( Campanini et al 2016 , Jiang et al 2017 ), we performed independent evolutionary analyses on each of the three OBP subfamilies identified (data not shown).…”

Identification of olfactory genes of a forensically important blow fly, Aldrichina grahami (Diptera: Calliphoridae)

“…Notably, many OBPs have binding preference or higher affinity to specific odor compounds (Maida, Ziegelberger & Kaissling, 2003;Pophof, 2004). Based on the literature, OBPs can be divided into four sub-types according to sequence feature: "Classical" OBPs, "Dimer" OBPs, "Minus-C" OBPs and "Plus-C" OBPs (Campanini & De Brito, 2016;Zhou et al, 2004). In 2011, there is a study further classified the classical OBPs into three sub-families, as pheromone-binding proteins (PBPs), general odorant-binding proteins (GOBPs) and antennal-binding protein X homologs (ABPXs) (Zhang et al, 2011).…”

Peer Review #1 of "Identification of olfactory genes of a forensically important blow fly, Aldrichina grahami (Diptera: Calliphoridae) (v0.1)"

“…Notably, many OBPs have binding preference or higher affinity to specific odor compounds (Maida et al 2003;Pophof 2004). Based on the literature, OBPs can be divided into four sub-types according to sequence feature: 'Classical' OBPs, 'Dimer' OBPs, 'Minus-C' OBPs and 'Plus-C' OBPs (Campanini & de Brito 2016;Jing-JiangcZhou 2004). In 2011, there is a study further classified the classical OBPs into three subfamilies, as pheromone-binding proteins (PBPs), general odorant-binding proteins (GOBPs) and antennal-binding protein X homologs (ABPXs) (Zhang et al 2011).…”