Taxonomic group: bacteria / Tenericutes
(Phylum: Tenericutes)
NCBI PubMed ID: 7811721Publication DOI: 10.1016/0005-2760(94)90063-9Journal NLM ID: 0217513Publisher: Elsevier
Institutions: Department of Physical Chemistry, Umeå University, Sweden
The structure of one glucolipid from the membrane of Acholeplasma laidlawii, strain A-EF22, was determined. This glucolipid is synthesized only when a large fraction of saturated, straight-chain fatty acids are incorporated into the membrane lipids of strain A-EF22. The lipid was studied by 1H- and 13C-NMR spectroscopy. The structure of the lipid is 1,2-diacyl-3-O-[6-O-acyl-(α-D-glucopyranosyl)]-sn-glycerol. The result for this lipid shows that a previously published structure, based on incomplete chemical analyses, was incorrect. The phase equilibria for 1,2-diacyl-3-O-[6-O-acyl-(α-D-glucopyranosyl)]- sn-glycerol and the two dominating lipids in A. laidlawii, monoglucosyldiacylglycerol and diglucosyldiacylglycerol, are discussed and related to the chemical structure of the lipids.
Structure type: oligomer
Trivial name: glycosyldiacylglycerol
Compound class: glycolipid, glycosyldiacylglycerol
Contained glycoepitopes: IEDB_142488,IEDB_144998,IEDB_146664,IEDB_983931,SB_192
Methods: 13C NMR, 1H NMR
Comments, role: representative structure
Related record ID(s): 109545, 109547
NCBI Taxonomy refs (TaxIDs): 2148Reference(s) to other database(s): CCSD:
45270, CBank-STR:378
Show glycosyltransferases
There is only one chemically distinct structure:
Taxonomic group: plant / Streptophyta
(Phylum: Streptophyta)
Organ / tissue: leaf
NCBI PubMed ID: 7865537Publication DOI: 10.1016/0005-2736(94)00248-NJournal NLM ID: 0217513Publisher: Elsevier
Institutions: Laboratoire de Physiologie Végétale, Université de Neuchâtel, Switzerland
The transfer of organelle of newly synthesized lipid molecules from inner envelope to thylakoid membranes, as well as their subsequent transbilayer distribution in these membranes, have been studied in intact chloroplasts isolated from young and mature spinach, young pea and mature lettuce leaves, using a recently developed methodology (Rawyler, A., Meylan, M. and Siegenthaler, P.A. (1992) Biochim. Biophys. Acta 1104, 331-341). Three radiolabelled precursors were used. UDP-[14C]galactose allowed to follow the fate of mono- and digalactosyldiacylglycerol (MGDG and DGDG) made from polyunsaturated, preexisting diacylglycerol (DAG), whereas [14C]acetate and [14C]glycerol 3-phosphate were used to follow the fate of MGDG and phosphatidylglycerol (PG), respectively, after de novo synthesis. MGDG, DGDG and PG molecules assembled at the envelope level were found to be exportable to thylakoids in amounts strictly proportional to the amounts synthesized, provided that the necessary substrates were not limiting. Lipid export was class-selective; under our conditions, as much as 50-80% of the MGDG, 87% of the PG and 20-30% of the DGDG synthesized were exported to thylakoids. However, within the MGDG class labelled from [14C]acetate, there was hardly any selectivity in the export of its various molecular species. For MGDG, the proportionality coefficient, which reflects the efficiency of the export process, was higher in chloroplasts from young than from mature leaves, and higher in spinach than in pea and lettuce. Temperature affected the efficiency of galactolipid export in a class-dependent way. MGDG synthesis and export had similar Q10 values of about 4 in young and 3 in mature spinach leaves, while the Q10 of DGDG export was higher than that of its synthesis. In most cases, the transmembrane distribution of labelled lipids in thylakoids was found to match closely the corresponding distribution of mass, regardless of plant age and species and of incubation time and temperature. In some cases however, small but significant differences occurred between the label and the mass transbilayer distributions of MGDG (labelled molecules more inwardly oriented), DGDG and PG (more outwardly oriented). We propose a general model in which the thylakoid lipid asymmetry is primarily preestablished in the chloroplast envelope by the topography of its lipid-synthesizing enzymes, together with the occurrence of relatively fast lateral diffusion and translocation rates of the newly synthesized lipids. Transient fusions between inner envelope and thylakoid membranes would allow lipid export by lateral diffusion and build the observed lipid asymmetry in the latter.
chloroplast, thylakoid, lipid synthesis, mono(di)galactosyldiacylglycerol, lipid asymmetry
Structure type: oligomer
Trivial name: glycosyldiacylglycerol
Compound class: glycolipid, glycosyldiacylglycerol
Contained glycoepitopes: IEDB_142488,IEDB_144998,IEDB_146664,IEDB_983931,SB_192
Comments, role: representative structure
NCBI Taxonomy refs (TaxIDs): 3888,
3562,
4236Reference(s) to other database(s): CCSD:
45270, CBank-STR:378
Show glycosyltransferases
There is only one chemically distinct structure:
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