Determination of Acetyl-CoA and Malonyl-CoA in Germinating Rice Seeds Using the LC-MS/MS Technique

AMP-activated protein kinase (AMPK) has previously been demonstrated to phosphorylate and inactivate skeletal muscle acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of malonyl-CoA, an inhibitor of carnitine palmitoyltransferase 1 and fatty acid oxidation. Contraction-induced activation of AMPK with subsequent phosphorylation/inactivation of ACC has been postulated to be responsible in part for the increase in fatty acid oxidation that occurs in muscle during exercise. These studies were designed to answer the question: Does phosphorylation of ACC by AMPK make palmitoyl-CoA a more effective inhibitor of ACC? Purified rat muscle ACC was subjected to phosphorylation by AMPK. Activity was determined on nonphosphorylated and phosphorylated ACC preparations at acetyl-CoA concentrations ranging from 2 to 500 μM and at palmitoyl-CoA concentrations ranging from 0 to 100 μM. Phosphorylation resulted in a significant decline in the substrate saturation curve at all palmitoyl-CoA concentrations. The inhibitor constant for palmitoyl-CoA inhibition of ACC was reduced from 1.7 ± 0.25 to 0.85 ± 0.13 μM as a consequence of phosphorylation. At 0.5 mM citrate, ACC activity was reduced to 13% of control values in response to the combination of phosphorylation and 10 μM palmitoyl-CoA. Skeletal muscle ACC is more potently inhibited by palmitoyl-CoA after having been phosphorylated by AMPK. This may contribute to low-muscle malonyl-CoA values and increasing fatty acid oxidation rates during long-term exercise when plasma fatty acid concentrations are elevated.

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Regulation of fatty acid synthesis and malonyl-CoA content in mouse brown adipose tissue in response to cold-exposure, starvation or re-feeding

Biochemical Journal ◽

10.1042/bj2430437 ◽

1987 ◽

Vol 243 (2) ◽

pp. 437-442 ◽

Cited By ~ 20

Author(s):

M G Buckley ◽

E A Rath

Keyword(s):

Adipose Tissue ◽

Fatty Acid ◽

Brown Adipose Tissue ◽

Fatty Acid Synthesis ◽

Cold Exposure ◽

Acid Synthesis ◽

Acetyl Coa Carboxylase ◽

Acetyl Coa ◽

Malonyl Coa ◽

Brown Adipose

1. The effect of nutritional status on fatty acid synthesis in brown adipose tissue was compared with the effect of cold-exposure. Fatty acid synthesis was measured in vivo by 3H2O incorporation into tissue lipids. The activities of acetyl-CoA carboxylase and fatty acid synthetase and the tissue concentrations of malonyl-CoA and citrate were assayed. 2. In brown adipose tissue of control mice, the tissue content of malonyl-CoA was 13 nmol/g wet wt., higher than values reported in other tissues. From the total tissue water content, the minimum possible concentration was estimated to be 30 microM 3. There were parallel changes in fatty acid synthesis, malonyl-CoA content and acetyl-CoA carboxylase activity in response to starvation and re-feeding. 4. There was no correlation between measured rates of fatty acid synthesis and malonyl-CoA content and acetyl-CoA carboxylase activity in acute cold-exposure. The results suggest there is simultaneous fatty acid synthesis and oxidation in brown adipose tissue of cold-exposed mice. This is probably effected not by decreases in the malonyl-CoA content, but by increases in the concentration of free long-chain fatty acyl-CoA or enhanced peroxisomal oxidation, allowing shorter-chain fatty acids to enter the mitochondria independent of carnitine acyltransferase (overt form) activity.

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Regulation of myocardial fatty acid oxidation by substrate supply

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.281.4.h1561 ◽

2001 ◽

Vol 281 (4) ◽

pp. H1561-H1567 ◽

Cited By ~ 37

Author(s):

Sarah L. Longnus ◽

Richard B. Wambolt ◽

Rick L. Barr ◽

Gary D. Lopaschuk ◽

Michael F. Allard

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

Acid Oxidation ◽

Acetyl Coa ◽

Regulatory Pathways ◽

Oxidation Rates ◽

Substrate Supply ◽

Exogenous Substrate ◽

Malonyl Coa ◽

Myocardial Substrate

We tested the hypothesis that myocardial substrate supply regulates fatty acid oxidation independent of changes in acetyl-CoA carboxylase (ACC) and 5′-AMP-activated protein kinase (AMPK) activities. Fatty acid oxidation was measured in isolated working rat hearts exposed to different concentrations of exogenous long-chain (0.4 or 1.2 mM palmitate) or medium-chain (0.6 or 2.4 mM octanoate) fatty acids. Fatty acid oxidation was increased with increasing exogenous substrate concentration in both palmitate and octanoate groups. Malonyl-CoA content only rose as acetyl-CoA supply from octanoate oxidation increased. The increases in octanoate oxidation and malonyl-CoA content were independent of changes in ACC and AMPK activity, except that ACC activity increased with very high acetyl-CoA supply levels. Our data suggest that myocardial substrate supply is the primary mechanism responsible for alterations in fatty acid oxidation rates under nonstressful conditions and when substrates are present at physiological concentrations. More extreme variations in substrate supply lead to changes in fatty acid oxidation by the additional involvement of intracellular regulatory pathways.

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THE FORMATION OF ACETOACETATE FROM ACETYL COENZYME A, MALONYL COENZYME A, AND PYRUVATE BY WASHED MITOCHONDRIA ISOLATED FROM GUINEA PIG LIVER

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y63-227 ◽

1963 ◽

Vol 41 (1) ◽

pp. 1997-2011

Author(s):

F. Sauer

Keyword(s):

Guinea Pig ◽

Coenzyme A ◽

Inhibitory Effects ◽

Significant Extent ◽

Acetyl Coa ◽

Pig Liver ◽

Malonyl Coa ◽

Binding Agents ◽

Guinea Pig Liver ◽

Tracer Experiments

Washed mitochondria isolated from guinea pig liver were capable of synthesizing acetoacetate from pyruvate. Both acetyl-CoA and malonyl-CoA were incorporated into acetoacetate in the presence of pyruvate. However, without pyruvate, only acetyl-CoA was incorporated to any significant extent. Tracer experiments indicated that although malonyl-CoA was incorporated into acetoacetate, increased acetoacetate synthesis in the presence of pyruvate plus malonyl-CoA resulted primarily from increased pyruvate incorporation.The results of the present experiments indicated that a CO2fixation step was involved in the conversion of pyruvate to acetoacetate. Evidence in favor of this was based on the inhibitory effects of avidin (with partial reversal by biotin), stimulation with increasing bicarbonate concentration, and increased acetoacetate synthesis in the presence of malonyl-CoA.Sulphydryl binding agents completely inhibited acetoacetate synthesis from pyruvate. In the formation of acetoacetate, carbon atom 1 of pyruvate was eliminated. This indicated that pyruvate was converted into an active 2-carbon unit.

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Engineering intracellular malonyl-CoA availability in microbial hosts and its impact on polyketide and fatty acid synthesis

Applied Microbiology and Biotechnology ◽

10.1007/s00253-020-10643-7 ◽

2020 ◽

Vol 104 (14) ◽

pp. 6057-6065 ◽

Cited By ~ 1

Author(s):

Lars Milke ◽

Jan Marienhagen

Keyword(s):

Fatty Acid ◽

Metabolic Engineering ◽

Fatty Acid Synthesis ◽

Building Block ◽

Acid Synthesis ◽

Microbial Synthesis ◽

Acetyl Coa ◽

Carboxylase Activity ◽

Cell Factories ◽

Malonyl Coa

AbstractMalonyl-CoA is an important central metabolite serving as the basic building block for the microbial synthesis of many pharmaceutically interesting polyketides, but also fatty acid–derived compounds including biofuels. Especially Saccharomyces cerevisiae, Escherichia coli, and Corynebacterium glutamicum have been engineered towards microbial synthesis of such compounds in recent years. However, developed strains and processes often suffer from insufficient productivity. Usually, tightly regulated intracellular malonyl-CoA availability is regarded as the decisive bottleneck limiting overall product formation. Therefore, metabolic engineering towards improved malonyl-CoA availability is essential to design efficient microbial cell factories for the production of polyketides and fatty acid derivatives. This review article summarizes metabolic engineering strategies to improve intracellular malonyl-CoA formation in industrially relevant microorganisms and its impact on productivity and product range, with a focus on polyketides and other malonyl-CoA-dependent products.Key Points• Malonyl-CoA is the central building block of polyketide synthesis.• Increasing acetyl-CoA supply is pivotal to improve malonyl-CoA availability.• Improved acetyl-CoA carboxylase activity increases availability of malonyl-CoA.• Fatty acid synthesis as an ambivalent target to improve malonyl-CoA supply.

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