Antenna-Specific Glutathione S-Transferase in Male Silkmoth Bombyx mori

Abstract

Glutathione S-transferases (GSTs) are multifunctional enzymes that are widely distributed in different species. GSTs detoxify exogenous and endogenous substances by conjugation to reduced glutathione. We characterized BmGSTD4, an antenna-specific GST, in male silkmoths. The full-length mRNA of Bmgstd4 was cloned by RACE-PCR and contained an open reading frame of 738 bp encoding a 245 amino acid protein. The antenna specificity of BmGSTD4 was validated at the mRNA and protein levels and BmGSTD4 was shown to localize in the sensillum of male silkmoth antennae. Homology modeling and multi-sequence alignment suggested that BmGSTD4 was a typical GST belonging to the δ class and had a canonical GST fold with a conserved N-terminus, including a glutathione-binding site and a C-terminal domain harboring a hydrophobic substrate-binding site. Restricted expression of BmGSTD4 in silkmoth antennae combined with GST activity suggested that BmGSTD4 was involved in the detoxification of harmful chemicals.

Glutathione-S-Transferases in the Olfactory Organ of the Noctuid Moth Spodoptera littoralis, Diversity and Conservation of Chemosensory Clades

“…As seen previously, SlitGSTd2 clusters in a conserved subgroup which includes BmGSTd4 and CpomGSTd2 for which predicted signal peptide (SP) sequences have been identified (Tan et al, 2014; Huang et al, 2017). SlitGSTd2 possesses also a predicted 22 amino acid SP at the N-terminus of the protein sequence, and its presence was confirmed by using RT-PCR with specific primers (Figure S1).…”

“…Moreover, all the delta GSTs from moths known to have an antennal specific expression, such as MsexGST-msolf from M. sexta (Robertson et al, 1999; Rogers et al, 1999), BmGSTd4 from B. mori (Tan et al, 2014), GST-haolf (Wang et al, 2004) from H. armigera and CpomGSTd2 (Huang et al, 2017) from C. pomonella fall within this clade.…”

“…However, as far as expression information is available, the second one with SlitGSTd2 is only composed of antennal-specific enzymes, such as B. mori, M. sexta , and A. transitella and C. pomonella GSTs (Rogers et al, 1999; Leal et al, 2009; Tan et al, 2014; Huang et al, 2017). MsexGST-msolf has been shown to degrade odorants in vitro and may have a role of ODE, especially toward aldehyde odorants, whereas CpomGSTd2 is active toward insecticides.…”

“…However, the expression of GSTs as well as their activities have been also highlighted in the olfactory organs of several insect species. Antennal expressed GSTs have been indeed identified in various moth species, such as Manduca sexta (Rogers et al, 1999), Helicoverpa armigera (Wang et al, 2004), Amyelois transitella (Leal et al, 2009), Bombyx mori (Tan et al, 2014), Chilo suppressalis (Liu et al, 2015a), Epiphyas postvittana (Corcoran et al, 2015), Cnaphalocris medinalis (Liu et al, 2015b), and Cydia pomonella (Huang et al, 2017), but also in the fruit fly Drosophila melanogaster (Younus et al, 2014) or in the beetles Agrilus planipennis (Mamidala et al, 2013), Dendroctonus valens (Gu et al, 2015), and Phyllotreta striolata (Wu et al, 2016). This particular localization led to the hypothesis of a possible dual function of GSTs in antennae where, besides their original implication in xenobiotic metabolism, they could play a role in the signal termination and in odorant clearance, as Odorant-Degrading Enzymes (ODEs, Vogt and Riddiford, 1981; Chertemps, 2017).…”

GLUTATHIONE S‐TRANSFERASE Genes IN THE RICE LEAFFOLDER, Cnaphalocrocis medinalis (LEPIDOPTERA: PYRALIDAE): IDENTIFICATION AND EXPRESSION PROFILES

“…In addition, GSTs are usually involved in stress‐activated signal pathways such as immune responses caused by bacterial infection (Huang et al., ; Huang et al., ). Moreover, antennal‐specific GSTs are believed to function as odorant‐degrading enzymes responsible for olfactory signal termination (Rogers et al., ; Tan et al., ).…”