(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > cellular organisms: NE > Eukaryota: NE > Opisthokonta: NE > Metazoa: NE > Eumetazoa: NE > Bilateria: NE > Protostomia: NE > Ecdysozoa: NE > Panarthropoda: NE > Arthropoda: NE > Mandibulata: NE > Pancrustacea: NE > Hexapoda: NE > Insecta: NE > Dicondylia: NE > Pterygota: NE > Neoptera: NE > Holometabola: NE > Diptera: NE > Brachycera: NE > Muscomorpha: NE > Eremoneura: NE > Cyclorrhapha: NE > Schizophora: NE > Acalyptratae: NE > Ephydroidea: NE > Drosophilidae: NE > Drosophilinae: NE > Drosophilini: NE > Drosophila [fruit fly, genus]: NE > Sophophora: NE > melanogaster group: NE > melanogaster subgroup: NE > Drosophila melanogaster: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA MWKLCQPRSRSRIKCFRFLILRCCPGFKRFSCQSAGDADSKVVKLSVGSV KGRRLSGIYGDEFYSFEGIPFAKPPLGKSRFVASQLADPWNSELDARQER PIPLQMDRRSGKVVGSEDCLYLNVYTKHFNESEPPLPVMVYIYGGAFRTG GAVKSKYGPDYLMSRDVVYVLFNYRLCSLGFLSMPSGKLDVPGNAGLHDQ LLALQWVSQHIRNFNGDPQNITLFGESAGAASVHFMMCLPHRFPLFHKAI MMSGSMLSPWVNAPDSDDIFCRLATSAGYEGPAEEVPILEFLRNVNAEKL IGHDFISPRDRCFGFLNPFAPVVGGLVAAPFQHLMKEAWSCEVPLLLGGT SFEGLVYYPFCQLDNGYMLELLKHEPAMVLPHELYQSMSVEERNTAADVL VKYHYGPRGITKSNITQILDLFSYKLFWHGIHRVVLSRLSHAQAPTYLYR FDFDSPKLNLMRNQLCGDDIKRGVCHADDLGYIFHKQAQAKQSLDSPEFL TIQRMVGILTTFARTGDPNCPETGPDLWMPVSTKSPFKALNIGQQVECVT QVEKDGLKVWNRLYSDLK
BACKGROUND: Insects respond to the spatial and temporal dynamics of a pheromone plume, which implies not only a strong response to 'odor on', but also to 'odor off'. This requires mechanisms geared toward a fast signal termination. Several mechanisms may contribute to signal termination, among which odorant-degrading enzymes. These enzymes putatively play a role in signal dynamics by a rapid inactivation of odorants in the vicinity of the sensory receptors, although direct in vivo experimental evidences are lacking. Here we verified the role of an extracellular carboxylesterase, esterase-6 (Est-6), in the sensory physiological and behavioral dynamics of Drosophila melanogaster response to its pheromone, cis-vaccenyl acetate (cVA). Est-6 was previously linked to post-mating effects in the reproductive system of females. As Est-6 is also known to hydrolyze cVA in vitro and is expressed in the main olfactory organ, the antenna, we tested here its role in olfaction as a putative odorant-degrading enzyme. RESULTS: We first confirm that Est-6 is highly expressed in olfactory sensilla, including cVA-sensitive sensilla, and we show that expression is likely associated with non-neuronal cells. Our electrophysiological approaches show that the dynamics of olfactory receptor neuron (ORN) responses is strongly influenced by Est-6, as in Est-6 degrees null mutants (lacking the Est-6 gene) cVA-sensitive ORN showed increased firing rate and prolonged activity in response to cVA. Est-6 degrees mutant males had a lower threshold of behavioral response to cVA, as revealed by the analysis of two cVA-induced behaviors. In particular, mutant males exhibited a strong decrease of male-male courtship, in association with a delay in courtship initiation. CONCLUSIONS: Our study presents evidence that Est-6 plays a role in the physiological and behavioral dynamics of sex pheromone response in Drosophila males and supports a role of Est-6 as an odorant-degrading enzyme (ODE) in male antennae. Our results also expand the role of Est-6 in Drosophila biology, from reproduction to olfaction, and highlight the role of ODEs in insect olfaction.
Title: Duplication and divergence of the genes of the alpha-esterase cluster of Drosophila melanogaster Robin C, Russell RJ, Medveczky KM, Oakeshott JG Ref: Journal of Molecular Evolution, 43:241, 1996 : PubMed
The alpha-esterase cluster of D. melanogaster contains 11 esterase genes dispersed over 60 kb. Embedded in the cluster are two unrelated open reading frames that have sequence similarity with genes encoding ubiquitin-conjugating enzyme and tropomyosin. The esterase amino acid sequences show 37-66% identity with one another and all but one have all the motifs characteristic of functional members of the carboxyl/cholinesterase multigene family. The exception has several frameshift mutations and appears to be a pseudogene. Patterns of amino acid differences among cluster members in relation to generic models of carboxyl/cholinesterase protein structure are broadly similar to those among other carboxyl/cholinesterases sequenced to date. However the alpha-esterases differ from most other members of the family in: their lack of a signal peptide; the lack of conservation in cysteines involved in disulfide bridges; and in four indels, two of which occur in or adjacent to regions that align with proposed substrate-binding sites of other carboxyl/cholinesterases. Phylogenetic analyses clearly identify three simple gene duplication events within the cluster. The most recent event involved the pseudogene which is located in an intron of another esterase gene. However, relative rate tests suggest that the pseudogene remained functional after the duplication event and has become inactive relatively recently. The distribution of indels also suggests a deeper node in the gene phylogeny that separates six genes at the two ends of the cluster from a block of five in the middle.
Drosophila melanogaster (Fruit fly) acetylcholinesterase H subunit