Expression Patterns of Drosophila Melanogaster Glutathione Transferases

SIMPLE SUMMARY: Glutathione transferases are key enzymes found in all living species. In insects, two classes of these enzymes are specific: the Delta and Epsilon classes. These classes of glutathione transferases are generally considered supports during the evolution for the adaptability of the species of an insect. We measured the expression levels of the 25 enzymes forming these two classes in different organs of Drosophila melanogaster. Some glutathione transferases are tissue-specific, others are specifically underexpressed in some tissues, and some appear expressed at the same level in all the tested tissues. All glutathione transferases present a specific pattern that does not depend on their sequence proximity. This study allows us to better understand the potential role of these enzymes by analyzing their expression profile and evolutionary links. ABSTRACT: Glutathione transferases (GSTs) are ubiquitous enzymes that catalyze the conjugation of glutathione to various molecules. Among the 42 GSTs identified in Drosophila melanogaster, Delta and Epsilon are the largest classes, with 25 members. The Delta and Epsilon classes are involved in different functions, such as insecticide resistance and ecdysone biosynthesis. The insect GST number variability is due mainly to these classes. Thus, they are generally considered supports during the evolution for the adaptability of the insect species. To explore the link between Delta and Epsilon GST and their evolution, we analyzed the sequences using bioinformatic tools. Subgroups appear within the Delta and Epsilon GSTs with different levels of diversification. The diversification also appears in the sequences showing differences in the active site. Additionally, amino acids essential for structural stability or dimerization appear conserved in all GSTs. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the transcripts corresponding to these two classes are heterogeneously expressed within D. melanogaster. Some GSTs, such as GSTD1, are highly expressed in all tissues, suggesting their general function in detoxification. Conversely, some others, such as GSTD11 or GSTE4, are specifically expressed at a high level specifically in antennae, suggesting a potential role in olfaction.