Genomic and phylogenetic analysis of insect carboxyl/cholinesterase genes

Abstract

The carboxyl/cholinesterase (CCE) superfamily is composed of functionally diverse proteins that hydrolyze carboxylic esters. CCEs are responsible not only for physiological regulation of particular endogenous compounds, such as hormones, pheromones, and acetylcholine, but also for the detoxification of exogenous compounds, such as those in the diet and in the environment. In some instances, CCEs are associated with insecticide resistance, 1) and the gene identification of CCEs is significant not only for elucidation of the mechanisms of insecticide resistance but also for the development of novel insecticidal compounds pesticides. Recent completion of genome projects and the availability of expressed sequence tag (EST) clones has enabled the identification of multiple CCEs in each insect species. 2-4) Here we describe the genomic and phylogenetic analyses of 425 insect CCEs found in eight insect species whose genomes have been completely sequenced, and discuss the implications of the constructed phylogenetic tree. Construction of the Phylogenetic TreeClustalW software was used to perform multiple sequence alignment prior to phylogenetic analysis. MEGA 4.0 5) was used to construct the phylogenetic tree using the neighborjoining method with the JTT matrix. To evaluate branch strength in the phylogenetic tree, bootstrap analysis of 500 replicates was performed. The amino acid sequences of genes used for phylogenetic analysis were retrieved from the National Center for Biotechnological Information site (http:// www.ncbi.nih.gov/). The accession number of each gene is listed in Supplemental Table S1. Potential signal peptides were predicted by the SignalP 3.0 program (http://www.cbs. dtu.dk/services/SignalP). Phylogenetic Analysis of Insect CCEsThe database search revealed 425 insect CCEs, including those from insects whose genomes have been completely sequenced, namely the dipterans Drosophila melanogaster, 1) Anopheles gambiae, 6) and Aedes aegypti; 7) the hymenopterans Apis mellifera 8) and Nasonia vitripennis; 9) lepidopteran Bombyx mori; 10,11) and the coleopteran Tribolium castaneum; 9) hemipteran Acyrthosiphon pisum. 12) The identified insect CCEs also included those of the lepidopterans Helicoverpa armigera and Spodoptera littoralis, in which EST clone analysis has been conducted, 13,14) and several other CCEs. Using these CCE amino acid sequences, a phylogenetic tree The complete genome sequence data of insects in five orders are now available. In this commentary we provide recent genomic and phylogenetic analyses of insect carboxyl/cholinesterases (CCEs). Multiple CCEs are found in each insect species, and at present the silkworm Bombyx mori has the largest number and diversity of CCEs. Phylogenetic analyses of the 425 CCE sequences identified species or order specific clustering, but for some CCEs 1:1 orthologous relationships were apparent. Phylogenetic analyses will be useful for further functional analysis of CCEs and the development of species-specific insecticides and/or synergists.

Rhodnius prolixus supergene families of enzymes potentially associated with insecticide resistance

“…A similar pattern of evolution is observed mostly for genes of the detoxification/dietary class in other insect species (Friedman, 2011). Support values for lower branches of the tree are always small when CCEs are analyzed (Oakeshott et al, 2005(Oakeshott et al, , 2010Tsubota and Shiotsuki, 2010a;Tsubota and Shiotsuki, 2010b). It is possible that the grouping of the 22 R. prolixus genes within the pheromone/ hormone processing class is an artifact and they are, in fact, from the detoxification/dietary class.…”

“…Based on their function and phylogenetic relationships, insect CCEs have been divided into three broad classes named detoxification/dietary, pheromone/hormone processing and neuro/developmental that in turn are divided into smaller, more specific clades (Montella et al, 2012;Oakeshott et al, 2005Oakeshott et al, , 2010Tsubota and Shiotsuki, 2010b). Of the three classes, only the neuro/developmental one seems to be consistently monophyletic but always with low bootstrap support.…”

An antennae‐enriched carboxylesterase from Spodoptera exigua displays degradation activity in both plant volatiles and female sex pheromones

“…The 13 clades of carboxylesterases are (A) mitochondrial, cytosolic and secreted esterases; (B) and (C) H igher and L ower dipteran microsomal α‐esterases; (D) cuticular/antennal esterases; (E) β‐esterases and pheromone esterases; (F, nonlepidopteran juventile hormone esterases; (G) Lepidopteran juventile hormone esterases; (H) glutactin; (I) uncharacterized clade; (J) acetylcholinesterases; (K) gliotactins; (L) neuroligins; and (M) neurotactins. This nomenclature is that used in the literature (Oakeshott et al ., ; T subota & S hiotsuki, ; D urand et al ., ).…”

Genomic adaptation to polyphagy and insecticides in a major East Asian noctuid pest

“…COE genes, which play an important role in the metabolism of a wide range of xenobiotics associated with plants and insecticides 22,[28][29][30] , also showed large expansions of lepidopteran and α classes ( Table 1, Supplementary Fig. 6a and Supplementary Table 15).…”