Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka, Japan.
Biosci Biotechnol Biochem. 2022 Jul 22;86(8):974-984. doi: 10.1093/bbb/zbac089.
Glycolipids are important components of cell membranes in several organisms. The major glycolipids in mammals are glycosphingolipids (GSLs), which are composed of ceramides. In mammals, GSLs are degraded stepwise from the non-reducing end of the oligosaccharides via exo-type glycosidases. However, endoglycoceramidase (EGCase), an endo-type glycosidase found in actinomycetes, is a unique enzyme that directly acts on the glycosidic linkage between oligosaccharides and ceramides to generate intact oligosaccharides and ceramides. Three molecular species of EGCase, namely EGCase I, EGCase II, and endogalactosylceramidase, have been identified based on their substrate specificity. EGCrP1 and EGCrP2, which are homologs of EGCase in pathogenic fungi, were identified as the first fungal glucosylceramide- and sterylglucoside-hydrolyzing glycosidases, respectively. These enzymes are promising targets for antifungal drugs against pathogenic fungi. This review describes the functions and properties of these microbial glycolipid-degrading enzymes, the molecular basis of their differential substrate specificity, and their applications.
糖脂是几种生物细胞膜的重要组成部分。哺乳动物中的主要糖脂是糖鞘脂（GSLs），由神经酰胺组成。在哺乳动物中，GSL 通过外切型糖苷酶从寡糖的非还原端逐步降解。然而，放线菌中存在的内切型糖苷酶——神经酰胺糖苷酶（EGCase）是一种独特的酶，它直接作用于寡糖和神经酰胺之间的糖苷键，生成完整的寡糖和神经酰胺。根据其底物特异性，已鉴定出三种分子种类的 EGCase，即 EGCase I、EGCase II 和内半乳糖基神经酰胺酶。EGCrP1 和 EGCrP2 是致病真菌中 EGCase 的同源物，分别被鉴定为第一种真菌葡萄糖神经酰胺和甾基葡萄糖苷水解糖苷酶。这些酶是针对致病真菌的抗真菌药物的有前途的靶标。本文综述了这些微生物糖脂降解酶的功能和性质、它们差异底物特异性的分子基础及其应用。
