Comparative analysis of the UDP-glycosyltransferase multigene family in insects

Department of Entomology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany.
Insect biochemistry and molecular biology (Impact Factor: 3.45). 12/2011; 42(2):133-47. DOI: 10.1016/j.ibmb.2011.11.006
Source: PubMed


UDP-glycosyltransferases (UGT) catalyze the conjugation of a range of diverse small lipophilic compounds with sugars to produce glycosides, playing an important role in the detoxification of xenobiotics and in the regulation of endobiotics in insects. Recent progress in genome sequencing has enabled an assessment of the extent of the UGT multigene family in insects. Here we report over 310 putative UGT genes identified from genomic databases of eight different insect species together with a transcript database from the lepidopteran Helicoverpa armigera. Phylogenetic analysis of the insect UGTs showed Order-specific gene diversification and inter-species conservation of this multigene family. Only one family (UGT50) is found in all insect species surveyed (except the pea aphid) and may be homologous to mammalian UGT8. Three families (UGT31, UGT32, and UGT305) related to Lepidopteran UGTs are unique to baculoviruses. A lepidopteran sub-tree constructed with 40 H. armigera UGTs and 44 Bombyx mori UGTs revealed that lineage-specific expansions of some families in both species appear to be driven by diversification in the N-terminal substrate binding domain, increasing the range of compounds that could be detoxified or regulated by glycosylation. By comparison of the deduced protein sequences, several important domains were predicted, including the N-terminal signal peptide, UGT signature motif, and C-terminal transmembrane domain. Furthermore, several conserved residues putatively involved in sugar donor binding and catalytic mechanism were also identified by comparison with human UGTs. Many UGTs were expressed in fat body, midgut, and Malpighian tubules, consistent with functions in detoxification, and some were expressed in antennae, suggesting a role in pheromone deactivation. Transcript variants derived from alternative splicing, exon skipping, or intron retention produced additional UGT diversity. These findings from this comparative study of two lepidopteran UGTs as well as other insects reveal a diversity comparable to this gene family in vertebrates, plants and fungi and show the magnitude of the task ahead, to determine biochemical function and physiological relevance of each UGT enzyme.

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    • "). UGTs in insects constitute multiple gene families, and many UGTs are highly expressed in the fat body, midgut, and Malpighian tubules (Ahn et al. 2012). Insect UGTs use UDP-glucose as the main donor of glucose in order to catalyze the glucosylation of small lipophilic compounds (Ahn et al. 2012). "
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    • "In addition , we found plastic and evolved differential regulation of a number of glutathione S-transferases and glycosyltransferaes (Fig. 5a,b), major constituents of the 'drug metabolism' class of genes enriched in category H3 (Fig. 3). Both glutathione S-transferases and glycosyltransferaes are gene families with well-known functions in insect detoxification responses (Despres et al. 2007;Ahn et al. 2012;Fang 2012;Heckel 2014). Finally, we also found enrichment of proteasome-relatedteins in plastic transcripts (Fig. 3, H1), and ubiquitintargeted protein degradation mediated by the proteasome is commonly associated with response to oxidative stressors such as those related to toxin metabolism (Halliwell 2006). "
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    • "In the tobacco hornworm, Manduca sexta, a GST restricted to pheromone sensilla called GST-msolf1 plays a significant role in sex pheromone detection by inactivating the aldehyde component of the sex pheromone blend (Rogers et al., 1999). UGTs are another group of enzymes linked to odorant and xenobiotic degradation (Ahn et al., 2012). In insects UGTs are known to assist in enzymatic detoxification by catalyzing the glycosylation of lipophilic compounds (Despres et al., 2007). "
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