RRC ID 3965
Author Michaelson LV, Zäuner S, Markham JE, Haslam RP, Desikan R, Mugford S, Albrecht S, Warnecke D, Sperling P, Heinz E, Napier JA.
Title Functional characterization of a higher plant sphingolipid Delta4-desaturase: defining the role of sphingosine and sphingosine-1-phosphate in Arabidopsis.
Journal Plant Physiol.
Abstract The role of Delta4-unsaturated sphingolipid long-chain bases such as sphingosine was investigated in Arabidopsis (Arabidopsis thaliana). Identification and functional characterization of the sole Arabidopsis ortholog of the sphingolipid Delta4-desaturase was achieved by heterologous expression in Pichia pastoris. A P. pastoris mutant disrupted in the endogenous sphingolipid Delta4-desaturase gene was unable to synthesize glucosylceramides. Synthesis of glucosylceramides was restored by the expression of Arabidopsis gene At4g04930, and these sphingolipids were shown to contain Delta4-unsaturated long-chain bases, confirming that this open reading frame encodes the sphingolipid Delta4-desaturase. At4g04930 has a very restricted expression pattern, transcripts only being detected in pollen and floral tissues. Arabidopsis insertion mutants disrupted in the sphingolipid Delta4-desaturase At4g04930 were isolated and found to be phenotypically normal. Sphingolipidomic profiling of a T-DNA insertion mutant indicated the absence of Delta4-unsaturated sphingolipids in floral tissue, also resulting in the reduced accumulation of glucosylceramides. No difference in the response to drought or water loss was observed between wild-type plants and insertion mutants disrupted in the sphingolipid Delta4-desaturase At4g04930, nor was any difference observed in stomatal closure after treatment with abscisic acid. No differences in pollen viability between wild-type plants and insertion mutants were detected. Based on these observations, it seems unlikely that Delta4-unsaturated sphingolipids and their metabolites such as sphingosine-1-phosphate play a significant role in Arabidopsis growth and development. However, Delta4-unsaturated ceramides may play a previously unrecognized role in the channeling of substrates for the synthesis of glucosylceramides.
Volume 149(1)
Pages 487-98
Published 2009-1
DOI 10.1104/pp.108.129411
PII pp.108.129411
PMID 18978071
PMC PMC2613699
MeSH Arabidopsis / enzymology* Arabidopsis / genetics Arabidopsis / growth & development Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Cloning, Molecular DNA, Bacterial / genetics Gene Expression Regulation, Plant Glucosylceramides / biosynthesis Lysophospholipids / metabolism* Mutagenesis, Insertional Open Reading Frames Oxidoreductases / genetics Oxidoreductases / metabolism* Phylogeny Pichia / genetics Sequence Deletion Sphingosine / analogs & derivatives* Sphingosine / metabolism
IF 6.305
Times Cited 66
Arabidopsis / Cultured plant cells, genes pst17972