scholarly journals The Role of Pyruvate Dehydrogenase and Acetyl-Coenzyme A Synthetase in Fatty Acid Synthesis in Developing Arabidopsis Seeds

2000 ◽  
Vol 123 (2) ◽  
pp. 497-508 ◽  
Author(s):  
Jinshan Ke ◽  
Robert H. Behal ◽  
Stephanie L. Back ◽  
Basil J. Nikolau ◽  
Eve Syrkin Wurtele ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Pyruvate Dehydrogenase ◽  
Coenzyme A ◽  
Acid Synthesis ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme

scholarly journals A Novel Cold-Sensitive Allele of the Rate-Limiting Enzyme of Fatty Acid Synthesis, Acetyl Coenzyme A Carboxylase, Affects the Morphology of the Yeast Vacuole through Acylation of Vac8p

2000 ◽  
Vol 20 (9) ◽  
pp. 2984-2995 ◽  
Author(s):  
Roger Schneiter ◽  
Cesar E. Guerra ◽  
Manfred Lampl ◽  
Verena Tatzer ◽  
Günther Zellnig ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Protein Targeting ◽  
Coenzyme A ◽  
Acid Synthesis ◽  
Vacuolar Membrane ◽  
Acetyl Coenzyme A ◽  
Rate Limiting ◽  
Acetyl Coenzyme A Carboxylase ◽  
Mutant Cells

ABSTRACT The yeast vacuole functions both as a degradative organelle and as a storage depot for small molecules and ions. Vacuoles are dynamic reticular structures that appear to alternately fuse and fragment as a function of growth stage and environment. Vac8p, an armadillo repeat-containing protein, has previously been shown to function both in vacuolar inheritance and in protein targeting from the cytoplasm to the vacuole. Both myristoylation and palmitoylation of Vac8p are required for its efficient localization to the vacuolar membrane (Y.-X. Wang, N. L. Catlett, and L. S. Weisman, J. Cell Biol. 140:1063–1074, 1998). We report that mutants with conditional defects in the rate-limiting enzyme of fatty acid synthesis, acetyl coenzyme A carboxylase (ACC1), display unusually multilobed vacuoles, similar to those observed in vac8 mutant cells. This vacuolar phenotype of acc1 mutant cells was shown biochemically to be accompanied by a reduced acylation of Vac8p which was alleviated by fatty acid supplementation. Consistent with the proposed defect of acc1 mutant cells in acylation of Vac8p, vacuolar membrane localization of Vac8p was impaired upon shiftingacc1 mutant cells to nonpermissive condition. The function of Vac8p in protein targeting, on the other hand, was not affected under these conditions. These observations link fatty acid synthesis and availability to direct morphological alterations of an organellar membrane.

Regulation of Acetyl-Coenzyme A Carboxylase and Acetyl-Coenzyme A Synthetase in Spinach Chloroplasts

1984 ◽  
Vol 39 (3-4) ◽  
pp. 268-275 ◽  
Author(s):  
Andreas Sauer ◽  
Klaus-Peter Heise
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Coenzyme A ◽  
Acid Synthesis ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Key Enzymes ◽  
Spinach Chloroplasts ◽  
Triton X

In analogy to chloroplast fatty acid synthesis from acetate the key enzymes of acetate fixation, acetyl-CoA synthetase and acetyl-CoA carboxylase, in rapidly Triton X-100 lysed spinach chloroplasts show an activation by light and deactivation in the dark. The stim ulation of acetyl-CoA carboxylase by dithiothreitol in darkened chloroplasts points to an involvement of reducing equivalents in the light activation of this enzyme. But more than by alterations of the activation state per se, these enzymes appear to be effected by changes in their catalytic activity due to differences in the proton-, Mg2+- and adenine nucleotide levels of the chloroplast stroma. Thus the pH dependence of both enzymes, as immediately extracted from Triton X-100 lysed chloroplasts, resembles that recently found for lipid incorporation of acetate into intact spinach chloroplasts in the light with an identical pH optim um of about pH 8.5 for the acetyl-CoA carboxylase. Moreover, in the same extracts both enzyme activities show the already postulated requirement for MgATP and free Mg and are com petitively inhibited by free ATP and ADP with respect to MgATP. But on account of the fact, that the extractable acetyl-CoA synthetase as opposed to the carboxylase activities exceed by far the lipid incorporation rates of acetate by illuminated chloroplasts before disruption, acetyl-CoA synthetase will be excluded as rate limiting step in fatty acid synthesis from acetate. From key enzymes of acetate fixation only the carboxylase appears to be involved therefore in the light regulation of acetate incorporation into long-chain fatty acids

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