Structure–activity analysis suggests an olfactory function for the unique antennal delta glutathione transferase of Apis mellifera

• Published in: FEBS letters Vol. 597; no. 24; pp. 3038 - 3048
• Main Authors: Schwartz, Mathieu, Boichot, Valentin, Muradova, Mariam, Fournier, Pablo, Senet, Patrick, Nicolai, Adrien, Canon, Francis, Lirussi, Frederic, Ladeira, Ruben, Maibeche, Martine, Chertemps, Thomas, Aubert, Emmanuel, Didierjean, Claude, Neiers, Fabrice
• Format: Journal Article
• Language: English
• Published: England Wiley 01.12.2023
• Subjects: Animals; antennae; Apis mellifera GSTD1; Bees; Biochemistry, Molecular Biology; Catalysis; Food and Nutrition; Glutathione - metabolism; glutathione transferase; Glutathione Transferase - metabolism; Life Sciences; odorant; stability; Sulfur; sulfur sandwich; glutathione transferase; Apis mellifera GSTD1; sulfur sandwich; antennae; odorant; stability
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.14770

Glutathione transferases (GST) are detoxification enzymes that conjugate glutathione to a wide array of molecules. In the honey bee Apis mellifera, AmGSTD1 is the sole member of the delta class of GSTs, with expression in antennae. Here, we structurally and biochemically characterized AmGSTD1 to elucidate its function. We showed that AmGSTD1 can efficiently catalyse the glutathione conjugation of classical GST substrates. Additionally, AmGSTD1 exhibits binding properties with a range of odorant compounds. AmGSTD1 has a peculiar interface with a structural motif we propose to call ‘sulfur sandwich’. This motif consists of a cysteine disulfide bridge sandwiched between the sulfur atoms of two methionine residues and is stabilized by CH…S hydrogen bonds and S…S sigma‐hole interactions. Thermal stability studies confirmed that this motif is important for AmGSTD1 stability and, thus, could facilitate its functions in olfaction. Here, we structurally and biochemically characterized the only member of the delta and epsilon glutathione transferase (GST) family found in the honey bee antennae—AmGSTD1. We found that AmGSTD1 is active towards odorants. We uncovered a unique new structural motif in AmGSTD1 termed the ‘sulfur sandwich’, which plays a pivotal role in thermal stabilization of the protein and could facilitate its putative olfactory functions.