RRC ID 30388
Author Sato N, Moriyama T.
Title Genomic and biochemical analysis of lipid biosynthesis in the unicellular rhodophyte Cyanidioschyzon merolae: lack of a plastidic desaturation pathway results in the coupled pathway of galactolipid synthesis.
Journal Eukaryot Cell
Abstract The acyl lipids making up the plastid membranes in plants and algae are highly enriched in polyunsaturated fatty acids and are synthesized by two distinct pathways, known as the prokaryotic and eukaryotic pathways, which are located within the plastids and the endoplasmic reticulum, respectively. Here we report the results of biochemical as well as genomic analyses of lipids and fatty acids in the unicellular rhodophyte Cyanidioschyzon merolae. All of the glycerolipids usually found in photosynthetic algae were found, such as mono- and digalactosyl diacylglycerol, sulfolipid, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. However, the fatty acid composition was extremely simple. Only palmitic, stearic, oleic, and linoleic acids were found as major acids. In addition, 3-trans-hexadecanoic acid was found as a very minor component in phosphatidylglycerol. Unlike the case for most other photosynthetic eukaryotes, polyenoic fatty acids having three or more double bonds were not detected. These results suggest that polyunsaturated fatty acids are not necessary for photosynthesis in eukaryotes. Genomic analysis suggested that C. merolae lacks acyl lipid desaturases of cyanobacterial origin as well as stearoyl acyl carrier protein desaturase, both of which are major desaturases in plants and green algae. The results of labeling experiments with radioactive acetate showed that the desaturation leading to linoleic acid synthesis occurs on phosphatidylcholine located outside the plastids. Monogalactosyl diacylglycerol is therefore synthesized by the coupled pathway, using plastid-derived palmitic acid and endoplasmic reticulum-derived linoleic acid. These results highlight essential differences in lipid biosynthetic pathways between the red algae and the green lineage, which includes plants and green algae.
Volume 6(6)
Pages 1006-17
Published 2007-6-1
DOI 10.1128/EC.00393-06
PII EC.00393-06
PMID 17416897
PMC PMC1951526
MeSH Algal Proteins / classification Algal Proteins / genetics Algal Proteins / metabolism* Amino Acid Sequence Fatty Acid Desaturases / classification Fatty Acid Desaturases / genetics Fatty Acid Desaturases / metabolism* Fatty Acids / chemistry Fatty Acids / metabolism Galactolipids / biosynthesis* Intracellular Membranes / chemistry Intracellular Membranes / metabolism Lipids / biosynthesis* Molecular Sequence Data Phylogeny Plastids / metabolism Plastids / ultrastructure Recombinant Fusion Proteins / genetics Recombinant Fusion Proteins / metabolism Rhodophyta / cytology Rhodophyta / genetics Rhodophyta / metabolism* Sequence Alignment
IF 2.992
Times Cited 66
Algae NIES-3377