Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Arabidopsis / cytology
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Arabidopsis / genetics
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Arabidopsis / physiology*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Brefeldin A / metabolism
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Cell Membrane / metabolism*
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Cell Polarity
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Ceramides / chemistry
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Ceramides / metabolism
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Endosomes / metabolism
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Enzyme Inhibitors / metabolism
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Fumonisins / metabolism
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Humans
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Indoleacetic Acids / metabolism
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Intracellular Membranes / metabolism
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Intracellular Membranes / ultrastructure
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Isoenzymes / genetics
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Isoenzymes / metabolism
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Membrane Proteins / chemistry*
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Molecular Sequence Data
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Oxidoreductases / antagonists & inhibitors
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Oxidoreductases / genetics
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Oxidoreductases / metabolism
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Protein Synthesis Inhibitors / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Secretory Pathway / physiology*
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Sequence Alignment
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Sphingolipids* / chemistry
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Sphingolipids* / metabolism
Substances
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Arabidopsis Proteins
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Ceramides
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Enzyme Inhibitors
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Fumonisins
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Indoleacetic Acids
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Isoenzymes
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Membrane Proteins
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Protein Synthesis Inhibitors
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Recombinant Fusion Proteins
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Sphingolipids
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Brefeldin A
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fumonisin B1
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Oxidoreductases
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dihydroceramide desaturase