Involvement of mitochondrial contact sites in the subcellular compartmentalization of phospholipid biosynthetic enzymes
| Autor: | Françoise Gasnier, Cédric Simonot, Odile Gateau-Roesch, D. Ardail, Pierre Louisot, F. Lerme |
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| Rok vydání: | 1993 |
| Předmět: |
Carboxy-Lyases
Phosphatidylethanolamine N-Methyltransferase Submitochondrial Particles Phospholipid CDPdiacylglycerol-Serine O-Phosphatidyltransferase Mitochondria Liver Biology Cell Fractionation Endoplasmic Reticulum Biochemistry Mice chemistry.chemical_compound Phosphatidylcholine Centrifugation Density Gradient Animals Molecular Biology Phospholipids Phosphatidylethanolamine Binding Sites Cell-Free System Endoplasmic reticulum Biological membrane Intracellular Membranes Methyltransferases Cell Biology Phosphatidylserine Microscopy Electron Membrane Liver chemistry Microsomes Liver Mitochondrial Swelling Biomarkers Phosphatidylserine decarboxylase |
| Zdroj: | Journal of Biological Chemistry. 268:25985-25992 |
| ISSN: | 0021-9258 |
| Popis: | The concerted synthesis of phospholipids derived from serine involving two microsomal enzymes (phosphatidylserine synthase and phosphatidylethanolamine N-methyltransferase) and a mitochondrial one (phosphatidylserine decarboxylase) occurs in reconstituted cell-free systems. Subfractionation of crude mitochondria after swelling and separating on a sucrose density gradient resulted in the isolation of two contact site-enriched fractions from total outer membranes and inner membranes, respectively. Estimation of marker enzyme activities shows a high recovery of glucose-6-phosphate phosphatase (a marker for the endoplasmic reticulum) associated with contact site-enriched fractions. Accordingly, the linked synthesis of phosphatidylserine, phosphatidylethanolamine, and at a lesser extent phosphatidylcholine can occur. This biosynthetic pathway was absent from purified contact site-enriched fractions correlative with the absence of glucose-6-phosphate phosphatase activity. Reconstitution experiments, including contact site-enriched fractions incubated with endoplasmic reticulum-rich fraction, led to the restoration of the linked synthesis of phospholipids, thereby demonstrating that a reversible association between these two fractions can occur. These functional interactions between the endoplasmic reticulum and mitochondria are confirmed at the ultrastructural level using either chemical or physical fixation before resin embedding. These results show that the interorganelle trafficking of lipids may involve only highly specialized microdomains of both membranes, thereby allowing the maintenance of a specific lipid composition and distribution within membranes. |
| Databáze: | OpenAIRE |
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