Abstract
Bee venom is a complex mixture composed of peptides, proteins with enzymatic properties, and low-molecular-weight compounds. Although the carboxylesterase in bee venom has been identified as an allergen, the enzyme’s role as a venom component has not been previously elucidated. Here, we show the lipolytic activity of a bumblebee (Bombus ignitus) venom carboxylesterase (BivCaE). The presence of BivCaE in the venom secreted by B. ignitus worker bees was confirmed using an anti-BivCaE antibody raised against a recombinant BivCaE protein produced in baculovirus-infected insect cells. The enzymatic activity of the recombinant BivCaE protein was optimal at 40 °C and pH 8.5. Recombinant BivCaE protein degrades triglycerides and exhibits high lipolytic activity toward long-chain triglycerides, defining the role of BivCaE as a lipolytic agent. Bee venom phospholipase A2 binds to mammalian cells and induces apoptosis, whereas BivCaE does not affect mammalian cells. Collectively, our data demonstrate that BivCaE functions as a lipolytic agent in bee venom, suggesting that BivCaE will be involved in distributing the venom via degradation of blood triglycerides.
Highlights
Carboxylesterases have a broad substrate specificity and are involved in energy homeostasis and lipid metabolism [1]
We show the lipolytic activity of a bumblebee (Bombus ignitus) venom carboxylesterase (BivCaE)
Bee venom is a complex mixture of bioactive substances, including various enzymes [9,10,13,14,26]
Summary
Carboxylesterases have a broad substrate specificity and are involved in energy homeostasis and lipid metabolism [1]. Carboxylesterases catalyze the hydrolysis of esters and thioesters, including lipids. Lipases catalyze the reactions of long-chain triacylglycerols, whereas carboxylesterases catalyze the hydrolysis of short-chain triacylglycerols [2,3]. Carboxylesterases have been demonstrated to play detoxifying roles against drugs and toxicants [1]. Carboxylesterases reportedly mediate physiological activities owing to their involvement in the detoxification or metabolism of insecticides [4] as well as the processing of dietary nicotine [5] and regulation of oxidative stress [6]. Carboxylesterases are identified as major enzymes responsible for detoxifying xenobiotics [4,5,7,8]. Carboxylesterases are present in bee venom [9,10] and wasp venom [11]
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