Identification and expression of odorant-binding proteins of the malaria-carrying mosquitoesAnopheles gambiae andAnopheles arabiensis

Abstract

Host preference and blood feeding are restricted to female mosquitoes. Olfaction plays a major role in host-seeking behaviour, which is likely to be associated with a subset of mosquito olfactory genes. Proteins involved in olfaction include the odorant receptors (ORs) and the odorant-binding proteins (OBPs). OBPs are thought to function as a carrier within insect antennae for transporting odours to the olfactory receptors. Here we report the annotation of 32 genes encoding putative OBPs in the malaria mosquito Anopheles gambiae and their tissue-specific expression in two mosquito species of the Anopheles complex; a highly anthropophilic species An. gambiae sensu stricto and an opportunistic, but more zoophilic species, An. arabiensis. RT-PCR shows that some of the genes are expressed mainly in head tissue and a subset of these show highest expression in female heads. One of the genes (agCP1588) which has not been identified as an OBP, has a high similarity (40%) to the Drosophila pheromone-binding protein 4 (PBPRP4) and is only expressed in heads of both An. gambiae and An. arabiensis, and at higher levels in female heads. Two genes (agCP3071 and agCP15554) are expressed only in female heads and agC15554 also shows higher expression levels in An. gambiae. The expression profiles of the genes in the two members of the Anopheles complex provides the first step towards further molecular analysis of the mosquito olfactory apparatus.

Odorant-Binding Proteins of the Malaria Mosquito Anopheles funestus sensu stricto

“…However, their respective orthologous genes in An. gambiae , AgamOBP11 and AgamOBP29, were classified as “classic” OBPs in previous studies [17].…”

Organization and function of Drosophila odorant binding proteins

“…In this regard, we found that the most abundant Obp transcript in the antenna, Obp19d , is expressed in epidermal cells and not accessory cells, consistent with the findings of (Park et al, 2000), and is thus unlikely to be secreted into sensillar lymph. It seems plausible that Obp19a binds ligands other than odorants, as may other Obps that are expressed outside the olfactory system (Arya et al, 2010; Li et al, 2005; Pitts et al, 2014). Not only are Obps highly diverse, but sensilla also are diverse in structure and function, as illustrated by the lack of visible pore tubules in trichoid sensilla of Drosophila (Shanbhag et al, 1999).…”

Characterisations of odorant-binding proteins in the tsetse fly Glossina morsitans morsitans

“…There are a large number of OBPs present within a variety of insect species [13] and identification of genes encoding OBPs has been mainly by means of bioinformatic approaches based on the characteristic features of the protein families [24–30]. These features include the six-cysteine OBPs signature, a size of 15–20 kDa, the α-helix pattern, the globular water-soluble nature and the presence of a signal peptide.…”