Glycobiology Advance Access originally published online on September 21, 2005
Glycobiology 2006 16(2):155-164; doi:10.1093/glycob/cwj043
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The N-glycosylation defect of cwh8
yeast cells causes a distinct defect in sphingolipid biosynthesis
2 Department of Medicine, University of Fribourg, Fribourg, Switzerland; and 3 Department of Biology, Institute of Microbiology, ETHZ, Zurich, Switzerland
1 To whom correspondence should be addressed; e-mail: andreas.conzelmann{at}unifr.ch
Received on August 19, 2005; revised on September 15, 2005; accepted on September 17, 2005
CWH8/YGR036c of Saccharomyces cerevisiae has been identified as a dolichylpyrophosphate (Dol-PP) phosphatase that removes a phosphate from the Dol-PP generated by the oligosaccharyltransferase (OST), while it adds N-glycans to nascent glycoproteins in the endoplasmic reticulum (ER). Lack of CWH8 was proposed to interrupt the so called dolichol (Dol) cycle by trapping Dol in the form of Dol-PP in the ER lumen. Indeed, cwh8D mutants display a severe deficiency in N-glycosylation. We find that cwh8D mutants have strongly reduced levels of inositolphosphorylceramide (IPC), whereas its derivative, mannosyl-(inositol-P)2-ceramide (M(IP)2C) is not affected. Microsomes of cwh8D contain normal ceramide synthase and IPC synthesis activities. Within a large panel of mutants affecting Dol dependent pathways such as N- or O-glycosylation, or glycosylphosphatidyl inositol (GPI)-anchoring, only the mutants having a deficiency of N-glycan addition show the defect in IPC biosynthesis. By mutating genes required for the addition of N-glycans or by treating cells with tunicamycin (Tm) one can similarly reduce the steady state level of IPC and exactly reproduce the phenotype of cwh8D cells. Some potential mechanisms by which the lack of N-glycans could lead to the sphingolipid abnormality were further explored.
Key words: AUR1 / dolichol / Golgi / unfolded protein response
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  W. Fei, G. Alfaro, B.-P. Muthusamy, Z. Klaassen, T. R. Graham, H. Yang, and C. T. Beh Genome-Wide Analysis of Sterol-Lipid Storage and Trafficking in Saccharomyces cerevisiae Eukaryot. Cell, February 1, 2008; 7(2): 401 - 414. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Sarkar, P. A. Leventis, C. I. Silvescu, V. N. Reinhold, H. Schachter, and G. L. Boulianne Null Mutations in Drosophila N-Acetylglucosaminyltransferase I Produce Defects in Locomotion and a Reduced Life Span J. Biol. Chem., May 5, 2006; 281(18): 12776 - 12785. [Abstract] [Full Text] [PDF]
|
|