Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Escherichia coli acetyl-CoA carboxylase (ACC) is composed of four different protein molecules. These proteins form a large but very unstable complex. Hints of a sub-complex between the biotin carboxylase (BC) and biotin carboxyl carrier protein (BCCP) subunits have been reported in the literature, but the complex was not isolated and thus the protein stoichiometry could not be determined. We report isolation of the BC.BCCP complex. By use of affinity chromatography using two different affinity tags it was shown that the complex consists of a two BCCP molecules per BC molecule. The molar ratio in the complex is the same as the ratio of the subunit proteins synthesized in vivo. We conclude that the complex consists of a dimer of BC plus four BCCP molecules instead of the 2BC.2BCCP complex previously assumed. This subunit ratio allows two conflicting models of the ACC mechanism to be rectified. We also report that the N-terminal 30 or so residues of BCCP are responsible for the interaction of BCCP with BC and that the BC.BCCP complex is a substrate for biotinylation in vitro.
...
PMID:The biotin carboxylase-biotin carboxyl carrier protein complex of Escherichia coli acetyl-CoA carboxylase. 1279 81

Methylcrotonylglycinuria (MCG; MIM 210200) is an autosomal recessive inherited human disorder caused by the deficiency of 3-methylcrotonyl-CoA carboxylase (MCC, E.C.6.4.1.4), involved in leucine catabolism. This mitochondrial enzyme is one of the four biotin-dependent carboxylases known in humans. MCC is composed of two different types of subunits, alpha and beta, encoded by the nuclear genes MCCA and MCCB, respectively, recently cloned and characterized. Several mutations have been identified, in both genes, the majority are missense mutations along with splicing mutations and small insertions/deletions. We have expressed four missense mutations, two MCCA and two MCCB mapping to highly evolutionarily conserved residues, by transient transfection of SV40-transformed deficient fibroblasts in order to confirm their pathogenic effect. All the missense mutations expressed resulted in null or severely diminished MCC activity providing direct evidence that they are disease-causing ones. The MCCA mutations have been analysed in the context of three-dimensional structural information modelling the changes in the crystallized biotin carboxylase subunit of the Escherichia coli acetyl-CoA carboxylase. The apparent severity of all the MCC mutations contrasts with the variety of the clinical phenotypes suggesting that there are other cellular and metabolic unknown factors that affect the resulting phenotype.
...
PMID:Functional analysis of MCCA and MCCB mutations causing methylcrotonylglycinuria. 1468 Sep 78

The yeast Pyc1 isoform of pyruvate carboxylase has been further characterized and shown to differ from the Pyc2 isoform in its K(a) for K(+) activation. Pyc1 differs from chicken liver pyruvate carboxylase in the lack of effect of acetyl-CoA on ADP phosphorylation by carbamoyl phosphate, which may be a result of differences in the loci of action of the effector between the two enzymes. Solvent D(2)O isotope effects have been measured with Pyc1 on the full pyruvate carboxylation reaction, the ATPase reaction in the absence of pyruvate, and the carbamoyl phosphate-ADP phosphorylation reaction for the first time for pyruvate carboxylase. Proton inventories indicate that the measured isotope effects are due to a single proton transfer step in the reaction. The inverse isotope effects observed in all reactions suggest that the proton transfer step converts the enzyme from an inactive to an active form. Kinetic measurements on the C249A mutant enzyme suggest that C249 is involved in the binding and action of enzyme activators K(+) and acetyl-CoA. C249 is not involved in ATP binding as was observed for the corresponding residue in the biotin carboxylase subunit of Escherichia coli acetyl-CoA carboxylase, nor is it directly responsible for the measured inverse (D)(k(cat)/K(m)) isotope effects. The size of the inverse isotope effects indicates that they may result from formation of a low-barrier hydrogen bond. Modification of the wild type and C249A mutant with o-phthalaldehyde suggests that C249 is involved in isoindole formation but that the modification of this residue is not directly responsible for the accompanying major loss of enzyme activity.
...
PMID:Kinetic characterization of yeast pyruvate carboxylase isozyme Pyc1 and the Pyc1 mutant, C249A. 1474 53

Acetyl-CoA carboxylase (ACC) catalyses the first step in fatty-acid biosynthesis. Owing to its role in primary metabolism, ACC has been exploited as a commercial herbicide target and identified as a chemically validated fungicide target. In animals, ACC is also a key regulator of fat metabolism. This function has made ACC a prime target for the development of anti-obesity and anti-Type II diabetes therapeutics. Despite its economic importance, there is a lack of published information on recombinant expression of ACC. We report here the expression of enzymically active fungal (Ustilago maydis ) ACC in Escherichia coli. The recombinant enzyme exhibited Km values of 0.14+/-0.013 mM and 0.19+/-0.041 mM for acetyl-CoA and ATP respectively, which are comparable with those reported for the endogenous enzyme. The polyketide natural product soraphen is a potent inhibitor of the BC (biotin carboxylase) domain of endogenous fungal ACC. Similarly, recombinant ACC activity was inhibited by soraphen with a K(i) of 2.1+/-0.9 nM. A truncated BC domain that included amino acids 2-560 of the full-length protein was also expressed in E. coli. The isolated BC domain was expressed to higher levels, and was more stable than full-length ACC. Although incapable of enzymic turnover, the BC domain exhibited high-affinity soraphen binding (Kd 1.1+/-0.3 nM), demonstrating a native conformation. Additional BC domains from the phytopathogenic fungi Magnaporthe grisea and Phytophthora infestans were also cloned and expressed, and were shown to exhibit high-affinity soraphen binding. Together, these reagents will be useful for structural studies and assay development.
...
PMID:Expression and characterization of recombinant fungal acetyl-CoA carboxylase and isolation of a soraphen-binding domain. 1476 11

Acetyl-CoA carboxylase catalyzes the committed step in fatty acid synthesis in all plants, animals, and bacteria. The Escherichia coli form is a multifunctional enzyme consisting of three separate proteins: biotin carboxylase, carboxyltransferase, and the biotin carboxyl carrier protein. The biotin carboxylase component, which catalyzes the ATP-dependent carboxylation of biotin using bicarbonate as the carboxylate source, has a homologous functionally identical subunit in the mammalian biotin-dependent enzymes propionyl-CoA carboxylase and 3-methylcrotonyl-CoA carboxylase. In humans, mutations in either of these enzymes result in the metabolic deficiency propionic acidemia or methylcrotonylglycinuria. The lack of a system for structure-function studies of these two biotin-dependent carboxylases has prevented a detailed analysis of the disease-causing mutations. However, structural data are available for E. coli biotin carboxylase as is a system for its overexpression and purification. Thus, we have constructed three site-directed mutants of biotin carboxylase that are homologous to three missense mutations found in propionic acidemia or methylcrotonylglycinuria patients. The mutants M169K, R338Q, and R338S of E. coli biotin carboxylase were selected for study to mimic the disease-causing mutations M204K and R374Q of propionyl-CoA carboxylase and R385S of 3-methylcrotonyl-CoA carboxylase. These three mutants were subjected to a rigorous kinetic analysis to determine the function of the residues in the catalytic mechanism of biotin carboxylase as well as to establish a molecular basis for the two diseases. The results of the kinetic studies have revealed the first evidence for negative cooperativity with respect to bicarbonate and suggest that Arg-338 serves to orient the carboxyphosphate intermediate for optimal carboxylation of biotin.
...
PMID:Kinetic characterization of mutations found in propionic acidemia and methylcrotonylglycinuria: evidence for cooperativity in biotin carboxylase. 1496 May 87

Pyruvate carboxylase (PC) is distributed in many eukaryotes as well as in some prokaryotes. PC catalyzes the ATP-dependent carboxylation of pyruvate to form oxalacetate. PC has three functional domains, one of which is a biotin carboxylase (BC) domain. The BC subunit of PC from Aquifex aeolicus (PC-beta) was crystallized in an orthorhombic form with space group P2(1)2(1)2, unit-cell parameters a = 92.4, b = 122.1, c = 59.0 A and one molecule in the asymmetric unit. Diffraction data were collected at 100 K on BL24XU at SPring-8. The crystal structure was determined by the molecular-replacement method and refined against 20.0-2.2 A resolution data, giving an R factor of 0.199 and a free R factor of 0.236. The crystal structure revealed that PC-beta forms a dimeric quaternary structure consisting of two molecules related by crystallographic twofold symmetry. The overall structure of PC-beta is similar to other biotin-dependent carboxylases, such as acetyl-CoA carboxylase (ACC). Although some parts of domain B were disordered in ACC, the corresponding parts of PC-beta were clearly determined in the crystal structure. From comparison between the active-site structure of ACC with ATP bound and a virtual model of PC-beta with ATP bound, it was shown that the backbone torsion angles of Glu203 in PC-beta change and some of water molecules in the active site of PC-beta are excluded upon ATP binding.
...
PMID:Structure of the biotin carboxylase subunit of pyruvate carboxylase from Aquifex aeolicus at 2.2 A resolution. 1499 73

The 3-hydroxypropionate cycle, a pathway for autotrophic carbon dioxide fixation, is reviewed with special emphasis on the biochemistry of CO2 fixing enzymes in Acidianus brierleyi, a thermophilic and acidophilic archeon. In the 3-hydroxypropionate cycle, two enzymes, acetyl-CoA carboxylase and propionyl-CoA carboxylase, catalyze CO2 fixation. It has been shown in A. brierleyi, and subsequently in Metallosphaera sedula, that acetyl-CoA carboxylase is promiscuous, acting equally well on acetyl-CoA and propionyl-CoA. The subunit structure of the acyl-CoA carboxylase was shown to be alpha4beta4gamma4. Gene cloning revealed that the genes encoding the three subunits are adjacent to each other. accC encodes the beta-subunit (59 kDa subunit, biotin carboxylase subunit), accB encodes the gamma-subunit (20 kDa subunit, biotin carboxyl carrier protein), and pccB encodes the alpha-subunit (62 kDa subunit, carboxyltransferase subunit). Sequence analyses showed that accC and accB are co-transcribed and that pccB is transcribed separately. Potential biotechnological applications for the 3-hydroxypropionate cycle are also presented.
...
PMID:Occurrence, biochemistry and possible biotechnological application of the 3-hydroxypropionate cycle. 1499 52

Acetyl CoA carboxylase (EC 6.4.1.2, ACC) catalyzes the ATP-dependent carboxylation of acetyl CoA to yield malonyl CoA, which is the first committed step in fatty acid synthesis. A pair of degenerate PCR primers were designed according to the conserved amino acid sequence of AccA from M. tuberculosis and S. coelicolor. The product of the PCR amplification, a DNA fragment of 250bp was used as a probe for screening the U32 genomic cosmid library and its gene, accA, coding the biotinylated protein subunit of acetyl CoA carboxylase, was successfully cloned from U32. The accA ORF encodes a 598-amino-acid protein with the calculated molecular mass of 63.7kD, with 70.1% of G + C content. A typical Streptomyces RBS sequence, AGGAGG, was found at the - 6 position upstream of the start codon GTG. Analysis of the deduced amino acid sequence showed the presence of biotin-binding site and putative ATP-bicarbonate interaction region, which suggested the U32 AccA may act as a biotin carboxylase as well as a biotin carrier protein. Gene accA was then cloned into the pET28 (b) vector and expressed solubly in E. coli BL21 (DE3) by 0.1 mmol/L IPTG induction. Western blot confirmed the covalent binding of biotin with AccA. Northern blot analyzed transcriptional regulation of accA by 5 different nitrogen sources.
...
PMID:[Cloning, expression and transcriptional analysis of biotin carboxyl carrier protein gene (accA) from Amycolatopsis mediterranei U32 ]. 1627 72

Biotin carboxylase catalyzes the ATP-dependent carboxylation of biotin and is one component of the multienzyme complex acetyl-CoA carboxylase that catalyzes the first committed step in fatty acid synthesis in all organisms. In Escherichia coli, biotin carboxylase exists as a homodimer where each subunit contains a complete active site. In a previous study (Janiyani, K., Bordelon, T., Waldrop, G.L., Cronan Jr., J.E., 2001. J. Biol. Chem. 276, 29864-29870), hybrid dimers were constructed where one subunit was wild-type and the other contained an active site mutation that reduced activity at least 100-fold. The activity of the hybrid dimers was only slightly greater than the activity of the mutant homodimers and far less than the expected 50% activity for completely independent active sites. Thus, there is communication between the two subunits of biotin carboxylase. The dominant negative effect of the mutations on the wild-type active site was interpreted as alternating catalytic cycles of the active sites in the homodimer. In order to test the hypothesis of oscillating catalytic cycles, mathematical modeling and numerical simulations of the kinetics of wild-type, hybrid dimers, and mutant homodimers of biotin carboxylase were performed. Numerical simulations of biotin carboxylase kinetics were the most similar to the experimental data when an oscillating active site model was used. In contrast, alternative models where the active sites were independent did not agree with the experimental data. Thus, the numerical simulations of the proposed kinetic model support the hypothesis that the two active sites of biotin carboxylase alternate their catalytic cycles.
...
PMID:Modeling and numerical simulation of biotin carboxylase kinetics: implications for half-sites reactivity. 1726 90

Inhibition of acetyl-CoA carboxylase (ACC), with its resultant inhibition of fatty acid synthesis and stimulation of fatty acid oxidation, has the potential to favorably affect, in a concerted manner, a multitude of the cardiometabolic risk factors associated with diabetes, obesity, and the metabolic syndrome. Studies in ACC2 knockout mice and in experimental animals treated with isozyme-specific antisense oligonucleotides or with isozyme-nonselective ACC inhibitors have demonstrated the potential for treating metabolic syndrome through this modality. Co-crystallization of the biotin carboxylase and carboxyltransferase domains of eukaryotic ACC in the presence of substrates and inhibitors has revealed characteristics of the catalytic center that can be exploited in drug discovery. A variety of structurally diverse, mechanistically distinct classes of ACC inhibitors have been disclosed in the scientific and patent literature. Isozyme-nonselective ACC inhibitors may provide the optimal therapeutic potential. However, demonstration of the full potential of isozyme-selective inhibitors, once identified, should reveal advantages and liabilities associated with single isozyme inhibition.
...
PMID:Inhibitors of mammalian acetyl-CoA carboxylase. 1822 Nov 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---