Is acyl-CoA cholesterol acyltransferase 2 the enzyme responsible for the esterification of okadaic acid in bivalves?

Harmful algal blooms of Dinophysis species produce diarrhetic shellfish poisoning toxins like okadaic acid (OA) that accumulate in shellfish, posing health risks and economic losses. This study investigated the enzymes involved in OA esterification, a key detoxification process in shellfish. Experiments using enzyme inhibitors and quantification of acyltransferases in mussels with varying OA levels suggest that one homolog of human acyl-CoA cholesterol acyltransferase 2 (ACAT2) is the main enzyme responsible for OA esterification. Mammal ACAT2 inhibitors reduced OA esterification in mussel digestive gland tissue. Additionally, immunoreactivity to human antibodies (ELISA) correlated positively with OA concentrations in naturally contaminated mussels. The tissue distribution and subcellular localization of the ACAT2 homolog also support its role in OA detoxification. These findings provide new insights into the mechanism of OA depuration in shellfish and may inform strategies to enhance detoxification rates.