Year: 2013
Type: dissertation
Abstract: Cytidinediphosphate diacylglycerol synthase (CDS) catalyzes the transfer of a cytidylyl group from CTP to phosphatidic acid so that CDP-diacylglycerol, an important intermediate in glycerolipid biosynthesis of prokaryotic and eukaryotic organisms, is formed. It serves as precursor of anionic phosphoglycerolipids such as phosphatidylinositol, phosphatidylglycerol and cardiolipin. In plant cells CDS isozymes are located in the envelope membranes of plastids, in the inner mitochondrial membranes and microsomes, especially the ER. These CDS isozymes are encoded by a small gene family that comprises five members in Arabidopsis thaliana, two of which have previously been shown to code for the plastidial isoforms and be essential for the biosynthesis of plastidial phosphatidylglycerol. In this work the focus have been on the extraplastidial CDS, encoded by CDS1, CDS2 and CDS3. These enzymes were demonstrated to be the integral membrane proteins of the ER and possess similar enzymatic properties. Unlike the CDS3 gene, the expression of which was only detectable during the generative growth phase, CDS1 and CDS2 genes are constitutively expressed. Single Arabidopsis mutants lacking either CDS1 or CDS2 showed a wild type phenotype whereas disruption of both genes led to a seedling lethal phenotype, which can be complemented by functional expression of either CDS1 or CDS2 cDNA in the mutants. Hence these genes have redundant but indispensible functions. Analyses of cds1cds2 showed that the cell division and expansion were arrested in the mutant. Based on data from phospholipid labeling and steady state lipid composition, the dramatic accumulation of phosphatidic acid and the decrease of phosphatidylinositol are probably the reasons for the severe consequence of Arabidopsis losing the microsomal CDS functions.
Source: RWTH Publications (RWTH Aachen)
Authors: Yonghong Zhou, Margarete Frentzen
Language: English
Subfield: Biochemistry
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W936459251