Unique catabolic pathway of glycosphingolipids in a hydrozoan, Hydra magnipapillata, involving endoglycoceramidase.
Endoglycoceramidase (EGCase; EC 3.2.1.123) is an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides of various glycosphingolipids. We detected strong EGCase activity in animals belonging to Cnidaria, Mollusca, and Annelida and cloned the enzyme from a hydra, Hydra magnipapillata. The hydra EGCase, consisting of 517 amino acid residues, showed 19.2% and 50.2% identity to the Rhodcoccus and jellyfish EGCases, respectively. The recombinant hydra enzyme, expressed in CHOP (Chinese hamster ovary cells expressing polyoma LT antigen) cells, hydrolyzed [14C]GM1a to produce [14C]ceramide with a pH optimum at 3.0-3.5. Whole mount in situ hybridization and immunocytochemical analysis revealed that EGCase was widely expressed in the endodermal layer, especially in digestive cells. GM1a injected into the gastric cavity was incorporated and then directly catabolized by EGCase to produce GM1a-oligosaccharide and ceramide, which were further degraded by exoglycosidases and ceramidase, respectively. However, hydra exoglycosidases did not hydrolyze GM1a directly. These results indicate that the EGCase is indispensable for the catabolic processing of dietary glycosphingolipids in hydra, demonstrating the unique catabolic pathway for glyosphingolipids in the animal.
Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
Yasuhiro
Y
Horibata
Keishi
K
Sakaguchi
Nozomu
N
Okino
Hiroshi
H
Iida
Masanori
M
Inagaki
Toshitaka
T
Fujisawa
Yoichiro
Y
Hama
Makoto
M
Ito
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002518:Ceramides / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D005677:G(M1) Ganglioside / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism*; D006829:Hydra / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection
D002518:Ceramides; D006028:Glycosphingolipids; D009844:Oligosaccharides; D005677:G(M1) Ganglioside; D006026:Glycoside Hydrolases; C050427:endoglycoceramidase