Yeast Sphingolipid Metabolism - AOCS Lipid Library
Figure 2. Hypothetical pathway of sphingolipid biosynthesis in plants. Functionally characterized enzymes are framed by a continuous line. Enzymes identified by sequence similarity alone are indicated by a different typeface (experimental data are missing). Hypothetical enzymes whose existence is predicted based on the presence of sphingolipid metabolites are framed by dotted lines. Some sphingolipid classes have been indicated as pool(s), since it is not known whether they represent a biochemical entity or different spatially separated pools. In the case of ceramide the existence of several different possible molecular species are indicated by LCB/FA combinations. Almost nothing is known about degradation of complex sphingolipids. No homolog of the yeast IPCase Isclp can be found in the Arabidopsis genome. GIPC glycosylinositolphosphoryl ceramide, GlcCer glycosylceramide, SM sphingomyeline, Cer ceramide, LCB long-chain base, LCB-1-P long-chain base-1-phosphate.
Yeast Sphingolipid Metabolism ..
Our knowledge of plant sphingolipid metabolism and function has significantly increased over the past years. This applies mainly to the identification and the functional characterization of genes and enzymes involved in sphingolipid biosynthesis. In addition a number of plant mutants have provided new insights into sphingolipid functions. Very little is still known about intracellular transport, spatial distribution, degradation and signaling functions of sphingolipids. However, combination ofArabidopsis genetics with lipidomics and cell biology will soon bring our understanding of these issues to a new level.
Therefore, this review will report on the progress of plant sphingolipids in an old-fashioned style: We will give an overview of plant sphingolipid pathways and describe gene by gene novel identifications, functional characterizations and plant mutants. If known, biological functions will be given for each gene. We are convinced that during the next years our knowledge will significantly increase and that future reviews will focus on specific biological functions of plant sphingolipid metabolites.
MetaCyc sphingolipid biosynthesis (yeast)
N2 - Studies in budding yeast, Saccharomyces cerevisiae, have established an important role for the target of rapamycin (TOR) signaling network in regulating cell growth and cell architecture through the control of gene expression, protein biosynthesis, protein trafficking, as well as organization of the actin cytoskeleton. The central component of this network is the TOR kinase, which assembles into two distinct membrane associated protein complexes, termed TORC1 and TORC2, where TORC1 is uniquely inhibited by rapamycin. A novel role for this network, in particular involving TORC2, has emerged recently with respect to the regulation of the biosynthesis of sphingolipids. Complex sphingolipids are integral components of cell membranes and their biosynthesis involves the production of important bioactive intermediates, including sphingoid long-chain bases (LCBs) and ceramides, which play distinct signaling roles crucial for cell growth and survival. Here, we review recent results demonstrating a role for TORC2 in the balanced production of these intermediates and discuss how this regulation appears to involve two distinct downstream effector branches of TORC2, namely, the plextrin homology (PH) domain containing proteins SLM1 and SLM2, as well as the AGC kinases YPK1 and YPK2. We describe how these components interact with other effectors of sphingolipid metabolism and impinge on actin cytoskeletal organization, stress response, and cell survival. Finally, we discuss the likely relevance of these findings for mammalian cells.
Sphingolipid biosynthesis pathway yeast
By sequence comparisons with closely related other yeasts and deducing degenerated primers eleven genes of the sphingolipid biosynthesis pathway of Pichia ciferrii could be isolated and sequenced: LCB1 (encodes a subunit of serine palmitoyltransferase), TSC10 (3-ketosphinganine reductase), LAG1 and LAF1 (ceramide synthases), LIP1 (subunit of ceramide synthases), DES1 (dihydroceramide-delta4-desaturase), YXC1 (ceramidase), 8DES (sphingolipid-delta8-desaturase), 9MTR (sphingolipid-C9-methyltransferase), GCS1 (ceramide glycosyltransferase) and LCB4 (LCB kinase).