Department of Bioscience and Biotechnology, Kyushu University Graduate School, Fukuoka, Japan.
Laboratory of Biochemistry, Gifu Pharmaceutical University, Gifu, Japan.
PLoS One. 2022 Aug 4;17(8):e0270804. doi: 10.1371/journal.pone.0270804. eCollection 2022.
Polyphenols in plants are important for defense responses against microorganisms, insect herbivory, and control of feeding. Owing to their antioxidant, anti-cancer, and anti-inflammatory activities, their importance in human nutrition has been acknowledged. However, metabolism of polyphenols derived from mulberry leaves in silkworms (Bombyx mori) remains unclear. Sulfotransferases (SULT) are involved in the metabolism of xenobiotics and endogenous compounds. The purpose of this study is to investigate the metabolic mechanism of polyphenols mediated by B. mori SULT. Here, we identified a novel SULT in silkworms (herein, swSULT ST3). Recombinant swSULT ST3 overexpressed in Escherichia coli effectively sulfated polyphenols present in mulberry leaves. swSULT ST3 showed high specific activity toward genistein among the polyphenols. Genistein-7-sulfate was produced by the activity of swSULT ST3. Higher expression of swSULT ST3 mRNA was observed in the midgut and fat body than in the hemocytes, testis, ovary, and silk gland. Polyphenols inhibited the aldo-keto reductase detoxification of reactive aldehydes from mulberry leaves, and the most noticeable inhibition was observed with genistein. Our results suggest that swSULT ST3 plays a role in the detoxification of polyphenols, including genistein, and contributes to the effects of aldo-keto reductase in the midgut of silkworms. This study provides new insight into the functions of SULTs and the molecular mechanism responsible for host plant selection in lepidopteran insects.
植物中的多酚对于防御微生物、昆虫取食和控制摄食等具有重要作用。由于其具有抗氧化、抗癌和抗炎活性，因此其在人类营养中的重要性已得到认可。然而，蚕（Bombyx mori）对桑叶中多酚的代谢仍不清楚。硫酸转移酶（SULT）参与了外源化合物和内源性化合物的代谢。本研究旨在探讨 B. mori SULT 介导的多酚代谢机制。在这里，我们鉴定了一种新型的蚕 SULT（swSULT ST3）。在大肠杆菌中过表达的重组 swSULT ST3 可有效硫酸化桑叶中的多酚。swSULT ST3 对多酚中的染料木黄酮表现出较高的特异性活性。swSULT ST3 的活性产生了染料木黄酮-7-硫酸盐。swSULT ST3 mRNA 在中肠和脂肪体中的表达水平高于血细胞、睾丸、卵巢和丝腺。多酚抑制了来自桑叶的醛酮还原酶对反应性醛的解毒作用，而对染料木黄酮的抑制作用最为明显。我们的结果表明，swSULT ST3 在多酚（包括染料木黄酮）的解毒中发挥作用，并有助于中肠中醛酮还原酶的作用。本研究为 SULT 功能以及鳞翅目昆虫对宿主植物选择的分子机制提供了新的见解。
