Acetyl-CoA Carboxylase

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Richard M. Denton - One of the best experts on this subject based on the ideXlab platform.

  • Purification and characterisation of an insulin-stimulated protein-serine kinase which phosphorylates Acetyl-CoA Carboxylase
    FEBS letters, 1998
    Co-Authors: Kate J. Heesom, S K Moule, Richard M. Denton
    Abstract:

    An insulin-stimulated protein kinase specific for Acetyl-CoA Carboxylase has been purified from rat epididymal adipose tissue using Mono-Q chromatography. The kinase binds to (and phosphorylates) the relatively inactive, dimeric form of Acetyl-CoA Carboxylase, but not to its active, polymeric form, and this property has been used to purify the kinase. Under the conditions used, phosphorylation by the purified kinase did not result in a detectable increase in Acetyl-CoA Carboxylase activity. These studies also led to the recognition of an `activator' protein which is capable of increasing the activity of Acetyl-CoA Carboxylase without changing its phosphorylation state. It is suggested that this `activator' protein, together with the insulin-activated Acetyl-CoA Carboxylase kinase, may play a role in the activation of Acetyl-CoA Carboxylase by insulin.

  • Evidence for a protein regulator from rat liver which activates Acetyl-CoA Carboxylase
    Biochemical Journal, 1993
    Co-Authors: K A Quayle, Richard M. Denton, Roger W. Brownsey
    Abstract:

    1. A regulator of Acetyl-CoA Carboxylase has been identified in high-speed supernatant fractions from rat liver. The regulator was found to activate highly purified Acetyl-CoA Carboxylase 2-3-fold at physiological citrate concentrations (0.1-0.5 mM). The effects of the regulator on Acetyl-CoA Carboxylase activity were dose-dependent, and half-maximal activation occurred in 7-8 min at 30 degrees C. 2. The Acetyl-CoA Carboxylase regulator was non-dialysable and was inactivated by heating or by exposure to carboxypeptidase. The regulator was enriched from rat liver cytosol by first removing the endogenous Acetyl-CoA Carboxylase and then using a combination of purification steps, including (NH4)2SO4 precipitation, ion-exchange chromatography and size-exclusion chromatography. The regulator activity appeared to be a protein with a molecular mass of approx. 75 kDa, which could be eluted from mono-Q with approx. 0.35 M KCl as a single peak of activity. 3. Studies of the effects of the regulator on phosphorylation or subunit size of Acetyl-CoA Carboxylase indicated that the changes in enzyme activity are most unlikely to be explained by dephosphorylation or by proteolytic cleavage. 4. The regulator co-migrates with Acetyl-CoA Carboxylase through several purification steps, including ion-exchange chromatography and precipitation with (NH4)2SO4; however, the proteins may be separated by Sepharose-avidin chromatography, and the association between the proteins is also disrupted by addition of avidin in solution. Furthermore, the binding of the regulator itself to DEAE-cellulose is altered by the presence of Acetyl-CoA Carboxylase. Taken together, these observations suggest that the effects of the regulator on Acetyl-CoA Carboxylase may be explained by direct protein-protein interaction in vitro.

S K Moule - One of the best experts on this subject based on the ideXlab platform.

  • Purification and characterisation of an insulin-stimulated protein-serine kinase which phosphorylates Acetyl-CoA Carboxylase
    FEBS letters, 1998
    Co-Authors: Kate J. Heesom, S K Moule, Richard M. Denton
    Abstract:

    An insulin-stimulated protein kinase specific for Acetyl-CoA Carboxylase has been purified from rat epididymal adipose tissue using Mono-Q chromatography. The kinase binds to (and phosphorylates) the relatively inactive, dimeric form of Acetyl-CoA Carboxylase, but not to its active, polymeric form, and this property has been used to purify the kinase. Under the conditions used, phosphorylation by the purified kinase did not result in a detectable increase in Acetyl-CoA Carboxylase activity. These studies also led to the recognition of an `activator' protein which is capable of increasing the activity of Acetyl-CoA Carboxylase without changing its phosphorylation state. It is suggested that this `activator' protein, together with the insulin-activated Acetyl-CoA Carboxylase kinase, may play a role in the activation of Acetyl-CoA Carboxylase by insulin.

  • Coenzyme A is a potent inhibitor of Acetyl-CoA Carboxylase from rat epididymal fat-pads.
    The Biochemical journal, 1992
    Co-Authors: S K Moule, N J Edgell, A C Borthwick, R M Denton
    Abstract:

    Rat epididymal fat-pad extracts have previously been shown to contain an insulin-stimulated Acetyl-CoA Carboxylase kinase, which is co-eluted from Mono Q ion-exchange chromatography with a potent inhibitor of Acetyl-CoA Carboxylase [Borthwick, Edgell & Denton (1990) Biochem. J. 270, 795-801]. A variety of tests, including reactivity with thiol reagents, identify this inhibitor as CoA. Inhibition requires the presence of MgATP, but is independent of any phosphorylation of the enzyme. The effect is complete in about 5 min and is associated with depolymerization of Acetyl-CoA Carboxylase. Half-maximal inhibition is observed at about 40 nM-CoA. The inhibitory effects of CoA can be partially reversed by incubation with citrate and more fully overcome by treatment of the enzyme with the insulin-stimulated Acetyl-CoA Carboxylase kinase.

Moritz Hunkeler - One of the best experts on this subject based on the ideXlab platform.

  • structural basis for regulation of human acetyl coa Carboxylase
    Nature, 2018
    Co-Authors: Moritz Hunkeler, Anna Hagmann, Edward Stuttfeld, Mohamed Chami, Yakir Guri, Henning Stahlberg, Timm Maier
    Abstract:

    Acetyl-CoA Carboxylase catalyses the ATP-dependent carboxylation of Acetyl-CoA, a rate-limiting step in fatty acid biosynthesis1,2. Eukaryotic Acetyl-CoA Carboxylases are large, homodimeric multienzymes. Human Acetyl-CoA Carboxylase occurs in two isoforms: the metabolic, cytosolic ACC1, and ACC2, which is anchored to the outer mitochondrial membrane and controls fatty acid β-oxidation1,3. ACC1 is regulated by a complex interplay of phosphorylation, binding of allosteric regulators and proteinprotein interactions, which is further linked to filament formation1,4–8. These filaments were discovered in vitro and in vivo 50 years ago7,9,10, but the structural basis of ACC1 polymerization and regulation remains unknown. Here, we identify distinct activated and inhibited ACC1 filament forms. We obtained cryo-electron microscopy structures of an activated filament that is allosterically induced by citrate (ACC–citrate), and an inactivated filament form that results from binding of the BRCT domains of the breast cancer type 1 susceptibility protein (BRCA1). While non-polymeric ACC1 is highly dynamic, filament formation locks ACC1 into different catalytically competent or incompetent conformational states. This unique mechanism of enzyme regulation via large-scale conformational changes observed in ACC1 has potential uses in engineering of switchable biosynthetic systems. Dissecting the regulation of Acetyl-CoA Carboxylase opens new paths towards counteracting upregulation of fatty acid biosynthesis in disease. Cryo-electron microscopy studies of distinct, catalytically active and inactive filaments of human Acetyl-CoA Carboxylase 1 reveal the structural basis of its regulation.

S J Wakil - One of the best experts on this subject based on the ideXlab platform.

  • Isolation and characterization of a novel Acetyl-CoA Carboxylase kinase from rat liver.
    The Journal of biological chemistry, 1994
    Co-Authors: A H Mohamed, Wei-yong Huang, W Huang, K V Venkatachalam, S J Wakil
    Abstract:

    Abstract Acetyl-CoA Carboxylase is regulated allosterically by citrate and covalently by a phosphorylation/dephosphorylation mechanism. We have isolated and purified from rat livers a novel kinase that phosphorylates and inactivates the Carboxylase. This kinase is bound to the Carboxylase and can be eluted in salt-rich solution. The native kinase exists as high molecular weight aggregates of a subunit that has a molecular weight of 40,000. The phosphorylation sites of the Carboxylase were determined after tryptic and cyanogen bromide digestions of 32P-labeled Carboxylase and separation of the peptides by various chromatographic procedures. Amino acid analyses of the phosphopeptides showed that the Ser77 and Ser1200 residues were the sites of phosphorylation. Treating the phosphorylated Carboxylase with the Mn(2+)-dependent Acetyl-CoA Carboxylase phosphatase 2 removed the phosphate and reactivated the Carboxylase. These results suggest that both this kinase and the Acetyl-CoA Carboxylase phosphatase 2 act at the same site(s) in the Acetyl-CoA Carboxylase molecule. Citrate dramatically inhibits the kinase-mediated phosphorylation of the Carboxylase, suggesting that the allosteric modification and activation by citrate render the phosphorylation sites inaccessible to the kinase and therefore maintain high Carboxylase activity. This observation indicates that there is a close interplay between the citrate effect on and phosphorylation of the Carboxylase in regulating its activity.

Louis Hue - One of the best experts on this subject based on the ideXlab platform.

  • Activation of hepatic Acetyl-CoA Carboxylase by glutamate and Mg2+ is mediated by protein phosphatase-2A.
    Biochemical Journal, 1996
    Co-Authors: Vinciane Gaussin, Louis Hue, Willy Stalmans, Mathieu Bollen
    Abstract:

    The activation of hepatic Acetyl-CoA Carboxylase by Na(+)-cotransported amino acids such as glutamine has been attributed mainly to the stimulation of its dephosphorylation by accumulating dicarboxylic acids, e.g. glutamate. We report here on a hepatic species of protein phosphatase-2A that activates Acetyl-CoA Carboxylase in the presence of physiological concentrations of glutamate or Mg2+ and, under these conditions, accounts for virtually all the hepatic Acetyl-CoA Carboxylase phosphatase activity. Glutamate also stimulated the dephosphorylation of a synthetic pentadecapeptide encompassing the Ser-79 phosphorylation site of rat Acetyl-CoA Carboxylase, but did not affect the dephosphorylation of other substrates such as phosphorylase. Conversely, protamine, which stimulated the dephosphorylation of phosphorylase, inhibited the activation of Acetyl-CoA Carboxylase. A comparison with various species of muscle protein phosphatase-2A showed that the stimulatory effects of glutamate and Mg2+ on the Acetyl-CoA Carboxylase phosphatase activity are largely mediated by the regulatory A subunit. Glutamate and Mg2+ emerge from our study as novel regulators of protein phosphatase-2A when acting on Acetyl-CoA Carboxylase.

  • Mechanism of activation of liver Acetyl-CoA Carboxylase by cell swelling.
    European journal of biochemistry, 1993
    Co-Authors: A. Baquet, Vinciane Gaussin, Willy Stalmans, Mathieu Bollen, Louis Hue
    Abstract:

    The activation of hepatic glycogen synthase by the amino-acid-induced cell swelling has been attributed to the stimulation of [glycogen-synthase]-phosphatase resulting from an increase in the intracellular content in glutamate and aspartate, and a decrease in intracellular Cl-, which is a compensatory response to cell swelling [Meijer, A. J., Baquet, A., Gustafson, L., van Woerkom, G. M. & Hue, L. (1992) J. Biol. Chem. 267, 5823-5828]. Here we studied whether the activation of Acetyl-CoA Carboxylase by cell swelling could be explained by the same mechanism. The activation of endogenous or purified Acetyl-CoA Carboxylase was measured in gel-filtered liver extracts or cytosols. No activation could be observed under basal conditions but a fivefold stimulation was obtained with concentrations of glutamate (20-25 mM) found in hepatocytes incubated with glutamine. A similar stimulation was also observed with other dicarboxylic acids such as malonate and succinate, or with metal ions like Mg2+, Ca2+ and Mn2+ (10 mM). The addition of 50-100 mM Cl- was found to inhibit the activation of Acetyl-CoA Carboxylase by some 20-30%. Mg2+ was also found to stimulate the activation of the endogenous glycogen synthase. The glutamate-stimulated and Mg(2+)-stimulated activation of glycogen synthase and Acetyl-CoA Carboxylase was unaffected by 10 microM inhibitor-2, a specific inhibitory protein of protein phosphatase-1, but could be nearly completely blocked by the phosphatase inhibitor microcystin-LR. Our data suggest that the amino-acid-induced activation of Acetyl-CoA Carboxylase and glycogen synthase in the liver occurs by a common ionic mechanism.