Demonstration of an oligosaccharide-diphosphodolichol diphosphatase activity whose subcellular localization is different than those of dolichyl-phosphate-dependent enzymes of the dolichol cycle

Journal of Lipid Research

Michaël Bosco¹  Patricia Busca¹  Christine Gravier-Pelletier¹  Soria Iatmanen-Harbi²  Ahmad Massarweh³  Isabelle Chantret³  Nicolas Auberger³  Clarice Tessier⁴  Stuart E.H. Moore⁴ 

[1] Université Denis Diderot, Paris 7, Paris, France;Université Pierre et Marie Curie, Paris 6, Paris, France;INSERM U1149, Paris, France;Université Paris Descartes, CICB-Paris, CNRS UMR8601, LCBPT, Paris, France;

关键词: oligosaccharide-diphosphodolichol;    endoplasmic reticulum;    Golgi apparatus;    isoprenoids;    phosphatases;    phospholipids/trafficking;   

DOI  :  

来源: DOAJ

【 摘 要 】

Oligosaccharyl phosphates (OSPs) are hydrolyzed from oligosaccharide-diphosphodolichol (DLO) during protein N-glycosylation by an uncharacterized process. An OSP-generating activity has been reported in vitro, and here we asked if its biochemical characteristics are compatible with a role in endoplasmic reticulum (ER)-situated DLO regulation. We demonstrate a Co2+-dependent DLO diphosphatase (DLODP) activity that splits DLO into dolichyl phosphate and OSP. DLODP has a pH optimum of 5.5 and is inhibited by vanadate but not by NaF. Polyprenyl diphosphates inhibit [3H]OSP release from [3H]DLO, the length of their alkyl chains correlating positively with inhibition potency. The diphosphodiester GlcNAc2-PP-solanesol is hydrolyzed to yield GlcNAc2-P and inhibits [3H]OSP release from [3H]DLO more effectively than the diphosphomonoester solanesyl diphosphate. During subcellular fractionation of liver homogenates, DLODP codistributes with microsomal markers, and density gradient centrifugation revealed that the distribution of DLODP is closer to that of Golgi apparatus-situated UDP-galactose glycoprotein galactosyltransferase than those of dolichyl-P-dependent glycosyltransferases required for DLO biosynthesis in the ER. Therefore, a DLODP activity showing selectivity toward lipophilic diphosphodiesters such as DLO, and possessing properties distinct from other lipid phosphatases, is identified. Separate subcellular locations for DLODP action and DLO biosynthesis may be required to prevent uncontrolled DLO destruction.

【 授权许可】

Unknown