Unsaturated fatty acid synthesis in sunflower (Helianthus annuus L.) seeds in response to night temperature

1983 ◽  
Vol 2 (5) ◽  
pp. 229-231 ◽  
Author(s):  
C. P. Rochester ◽  
J. G. Silver
2005 ◽  
Vol 56 (415) ◽  
pp. 1297-1303 ◽  
Author(s):  
Rafael Pleite ◽  
Marilyn J. Pike ◽  
Rafael Garcés ◽  
Enrique Martínez-Force ◽  
Stephen Rawsthorne

Lipids ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Xiaozhong Zheng ◽  
Douglas R. Tocher ◽  
Cathryn A. Dickson ◽  
J. Gordon Bell ◽  
Alan J. Teale

1984 ◽  
Vol 220 (2) ◽  
pp. 481-488 ◽  
Author(s):  
S Stymne ◽  
A K Stobart

The synthesis of triacylglycerols was investigated in microsomes (microsomal fractions) prepared from the developing cotyledons of sunflower (Helianthus annuus). Particular emphasis was placed on the mechanisms involved in controlling the C18- unsaturated-fatty-acid content of the oils. We have demonstrated that the microsomes were capable of: the transfer of oleate from acyl-CoA to position 2 of sn-phosphatidylcholine for its subsequent desaturation and the return of the polyunsaturated products to the acyl-CoA pool by further acyl exchange; the acylation of sn-glycerol 3-phosphate with acyl-CoA to yield phosphatidic acid, which was further utilized in diacyl- and tri-acylglycerol synthesis; and (3) the equilibrium of a diacylglycerol pool with phosphatidylcholine. The acyl exchange between acyl-CoA and position 2 of sn-phosphatidylcholine coupled to the equilibration of diacylglycerol and phosphatidylcholine brings about the continuous enrichment of the glycerol backbone with C18 polyunsaturated fatty acids for triacylglycerol production. Similar reactions were found to operate in another oilseed plant, safflower (Carthamus tinctorius L.). On the other hand, the microsomes of avocado (Persea americana) mesocarp, which synthesize triacylglycerol via the Kennedy [(1961) Fed. Proc. Fed. Am. Soc. Exp. Biol. 20, 934-940] pathway, were deficient in acyl exchange and the diacylglycerol in equilibrium phosphatidylcholine interconversion. The results provide a working model that helps to explain the relationship between C18- unsaturated-fatty-acid synthesis and triacylglycerol production in oilseeds.


2002 ◽  
Vol 30 (6) ◽  
pp. 1050-1055 ◽  
Author(s):  
H. Marrakchi ◽  
Y.-M. Zhang ◽  
C. O. Rock

Fatty acid biosynthesis is catalysed in most bacteria by a group of highly conserved proteins known as the Type II fatty acid synthase (FAS) system. The Type II system organization is distinct from its mammalian counterpart and offers several unique sites for selective inhibition by antibacterial agents. There has been remarkable progress in the understanding of the genetics, biochemistry and regulation of Type II FASs. One important advance is the discovery of the interaction between the fatty acid degradation regulator, FadR, and the fatty acid biosynthesis regulator, FabR, in the transcriptional control of unsaturated fatty acid synthesis in Escherichia coli. The availability of genomic sequences and high-resolution protein crystal structures has expanded our understanding of Type II FASs beyond the E. coli model system to a number of pathogens. The molecular diversity among the pathway enzymes is illustrated by the discovery of a new type of enoyl-reductase in Streptococcus pneumoniae [enoyl-acyl carrier protein (ACP) reductase II, FabK], the presence of two enoyl-reductases in Bacillus subtilis (enoyl-ACP reductases I and III, FabI and FabL), and the use of a new mechanism for unsaturated fatty acid formation in S. pneumoniae (trans-2-cis-3-enoyl-ACP isomerase, FabM). The solution structure of ACP from Mycobacterium tuberculosis revealed features common to all ACPs, but its extended C-terminal domain may reflect a specific interaction with very-long-chain intermediates.


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