Document Detail


Glycerolipid synthesis in Chlorella kessleri 11h. I. Existence of a eukaryotic pathway.
MedLine Citation:
PMID:  12842192     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The fatty acid distributions at the sn-1 and sn-2 positions in major chloroplast lipids of Chlorella kessleri 11h, monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG), were determined to show the coexistence of both C16 and C18 acids at the sn-2 position, i.e. of prokaryotic and eukaryotic types in these galactolipids. For investigation of the biosynthetic pathway for glycerolipids in C. kessleri 11h, cells were fed with [14C]acetate for 30 min, and then the distribution of the radioactivity among glycerolipids and their constituent fatty acids during the subsequent chase period was determined. MGDG and DGDG were labeled predominantly as the sn-1-C18-sn-2-C16 (C18/C16) species as early as by the start of the chase, which suggested the synthesis of these lipids within chloroplasts via a prokaryotic pathway. On the other hand, the sn-1-C18-sn-2-C18 (C18/C18) species of these galactolipids gradually gained radioactivity at later times, concomitant with a decrease in the radioactivity of the C18/C18 species of phosphatidylcholine (PC). The change at later times can be explained by the conversion of the C18/C18 species of PC into galactolipids through a eukaryotic pathway. The results showed that C. kessleri 11h, distinct from most of other green algal species that were postulated mainly to use a prokaryotic pathway for the synthesis of chloroplast lipids, is similar to a group of higher plants designated as 16:3 plants in terms of the cooperation of prokaryotic and eukaryotic pathways to synthesize chloroplast lipids. We propose that the physiological function of the eukaryotic pathway in C. kessleri 11h is to supply chloroplast membranes with 18:3/18:3-MGDG for their functioning, and that the acquisition of a eukaryotic pathway by green algae was favorable for evolution into land plants.
Authors:
Norihiro Sato; Mikio Tsuzuki; Akihiko Kawaguchi
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1633     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2003 Jul 
Date Detail:
Created Date:  2003-07-04     Completed Date:  2003-08-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  27-34     Citation Subset:  IM    
Affiliation:
School of Life Science, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo 192-0392, Japan. nsato@ls.toyaku.ac.jp
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MeSH Terms
Descriptor/Qualifier:
Acetates / metabolism
Chlorella / metabolism*
Chloroplasts / metabolism
Diglycerides / biosynthesis
Eukaryotic Cells / metabolism*
Fatty Acids / metabolism
Glycolipids / biosynthesis*
Kinetics
Prokaryotic Cells / metabolism
Chemical
Reg. No./Substance:
0/Acetates; 0/Diglycerides; 0/Fatty Acids; 0/Glycolipids

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