Sphingolipids Containing Very-Long-Chain Fatty Acids Define a Secretory Pathway for Specific Polar Plasma Membrane Protein Targeting in Arabidopsis

• Published in: The Plant cell 2011-06, Vol.23 (6), p.2362-2378
• Main Authors: Markham, Jonathan E., Molino, Diana, Gissot, Lionel, Bellec, Yannick, Hématy, Kian, Marion, Jessica, Belcram, Katia, Palauqui, Jean-Christophe, Satiat-JeuneMaître, Béatrice, Faure, Jean-Denis
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Arabidopsis; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Auxins; Brefeldin A; Brefeldin A - metabolism; Cell aggregates; Cell Membrane; Cell Membrane - metabolism; Cell membranes; Cell Polarity; Ceramides; Ceramides - chemistry; Ceramides - metabolism; Endosomes; Endosomes - metabolism; Enzyme Inhibitors; Enzyme Inhibitors - metabolism; Fatty acids; Fumonisins; Fumonisins - metabolism; Humans; Indoleacetic Acids; Indoleacetic Acids - metabolism; Intracellular Membranes; Intracellular Membranes - metabolism; Intracellular Membranes - ultrastructure; Isoenzymes; Isoenzymes - genetics; Isoenzymes - metabolism; Life Sciences; Lipids; Membrane Proteins; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membranes; Molecular Sequence Data; Oxidoreductases; Oxidoreductases - antagonists & inhibitors; Oxidoreductases - genetics; Oxidoreductases - metabolism; Plant cells; Plants; Protein Synthesis Inhibitors; Protein Synthesis Inhibitors - metabolism; Recombinant Fusion Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Secretory Pathway; Secretory Pathway - physiology; Seedlings; Sequence Alignment; Sphingolipids; Sphingolipids - chemistry; Sphingolipids - metabolism; Vegetal Biology
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.110.080473

Sphingolipids are a class of structural membrane lipids involved in membrane trafficking and cell polarity. Functional analysis of the ceramide synthase family in Arabidopsis thaliana demonstrates the existence of two activities selective for the length of the acyl chains. Very-long-acyl-chain (C > 18 carbons) but not long-chain sphingolipids are essential for plant development. Reduction of very-long-chain fatty acid sphingolipid levels leads in particular to auxin-dependent inhibition of lateral root emergence that is associated with selective aggregation of the plasma membrane auxin carriers AUX1 and PIN1 in the cytosol. Defective targeting of polar auxin carriers is characterized by specific aggregation of Rab-A2 a -and Rab-A1 e labeled early endosomes along the secretory pathway. These aggregates correlate with the accumulation of membrane structures and vesicle fragmentation in the cytosol. In conclusion, sphingolipids with very long acyl chains define a trafficking pathway with specific endomembrane compartments and polar auxin transport protein cargoes.