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

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Query: EC:6.2.1.1 (ACS)
78,556 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

After activation with NiCl2, the recombinant alpha subunit of the Ni-containing alpha2beta2 acetyl-CoA synthase/carbon monoxide dehydrogenase (ACS/CODH) catalyzes the synthesis of acetyl-CoA from CO, CoA, and a methyl group donated from the corrinoid-iron-sulfur protein (CoFeSP). The alpha subunit has two conformations (open and closed), and contains a novel [Fe4S4]-[Nip Nid] active site in which the proximal Nip ion is labile. Prior to Ni activation, recombinant apo-alpha contain only an Fe4S4 cluster. Ni-activated alpha subunits exhibit catalytic, spectroscopic and heterogeneity properties typical of alpha subunits contained in ACS/CODH. Evidence presented here indicates that apo-alpha is a monomer whereas Ni-treated alpha oligomerizes, forming dimers and higher molecular weight species including tetramers. No oligomerization occurred when apo-alpha was treated with Cu(II), Zn(II), or Co(II) ions, but oligomerization occurred when apo-alpha was treated with Pt(II) and Pd(II) ions. The dimer accepted only 0.5 methyl group/alpha and exhibited, upon treatment with CO and under reducing conditions, the NiFeC EPR signal quantifying to 0.4 spin/alpha. Dimers appear to consist of two types of alpha subunits, including one responsible for catalytic activity and one that provides a structural scaffold. Higher molecular weight species may be similarly constituted. It is concluded that Ni binding to the A-cluster induces a conformational change in the alpha subunit, possibly to the open conformation, that promotes oligomerization. These interrelated events demonstrate previously unrealized connections between (a) the conformation of the alpha subunit; (b) the metal which occupies the proximal/distal sites of the A-cluster; and (c) catalytic activity.
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PMID:Nickel-dependent oligomerization of the alpha subunit of acetyl-coenzyme a synthase/carbon monoxide dehydrogenase. 1788 77

Phylloquinone is the one-electron carrier at the A(1) site of photosystem I, and is essential for photosynthesis. Arabidopsis mutants deficient in early steps of phylloquinone synthesis do not become autotrophic and are seedling lethals, even when grown on sucrose-supplemented media. Here, we identify acyl-activating enzyme 14 (AAE14, At1g30520) as the o-succinylbenzoyl-coenzyme A (OSB-CoA) ligase acting in phylloquinone synthesis. Three aae14 mutant alleles, identified by reverse genetics, were found to be seedling lethal, to contain no detectable phylloquinone (< 0.1 pmol mg(-1) fresh weight) compared with 10 pmol mg(-1) fresh weight in wild-type leaves, and to accumulate OSB. AAE14 was able to restore menaquinone biosynthesis when expressed in an Escherichia coli mutant disrupted in the menE gene that encodes the bacterial OSB-CoA ligase. Weak expression of an AAE14 transgene in mutant plants (controlled by the uninduced XVE promoter) resulted in chlorotic, slow-growing plants that accumulated an average of 4.7 pmol mg(-1) fresh weight of phylloquinone. Inducing the XVE promoter in these plants, or expressing an AAE14 transgene under the control of the CaMV 35S promoter, led to full complementation of the mutant phenotype. aae14-mutant plants were also able to synthesize phylloquinone when provided with 1,4-dihydroxy-2-naphthoate, an intermediate in phylloquinone synthesis downstream of the OSB-CoA ligase reaction. Expression of an AAE14:GFP reporter construct indicated that the protein accumulated in discrete foci within the chloroplasts. This and other evidence suggests that the enzymes of phylloquinone synthesis from isochorismate may form a complex in the chloroplast stroma to facilitate the efficient channeling of intermediates through the pathway.
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PMID:The AAE14 gene encodes the Arabidopsis o-succinylbenzoyl-CoA ligase that is essential for phylloquinone synthesis and photosystem-I function. 1820 20

Acyl-CoA synthetase, which is one of the acid-thiol ligases (EC 6.2.1), plays key roles in metabolic and regulatory processes. This enzyme forms a carbon-sulfur bond in the presence of ATP and Mg(2+), yielding acyl-CoA thioesters from the corresponding free acids and CoA. This enzyme belongs to the superfamily of adenylate-forming enzymes, whose three-dimensional structures are analogous to one another. We here discovered a new reaction while studying the short-chain acyl-CoA synthetase that we recently reported (Hashimoto, Y., Hosaka, H., Oinuma, K., Goda, M., Higashibata, H., and Kobayashi, M. (2005) J. Biol. Chem. 280, 8660-8667). When l-cysteine was used as a substrate instead of CoA, N-acyl-l-cysteine was surprisingly detected as a reaction product. This finding demonstrated that the enzyme formed a carbon-nitrogen bond (EC 6.3.1 acid-ammonia (or amide) ligase (amide synthase); EC 6.3.2 acid-amino acid ligase (peptide synthase)) comprising the amino group of the cysteine and the carboxyl group of the acid. N-Acyl-d-cysteine, N-acyl-dl-homocysteine, and N-acyl-l-cysteine methyl ester were also synthesized from the corresponding cysteine analog substrates by the enzyme. Furthermore, this unexpected enzyme activity was also observed for acetyl-CoA synthetase and firefly luciferase, indicating the generality of the new reaction in the superfamily of adenylate-forming enzymes.
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PMID:Discovery of amide (peptide) bond synthetic activity in Acyl-CoA synthetase. 1830 11

In Archaea, acetate formation and ATP synthesis from acetyl-CoA is catalyzed by an unusual ADP-forming acetyl-CoA synthetase (ACD) (acetyl-CoA + ADP + P(i) acetate + ATP + HS-CoA) catalyzing the formation of acetate from acetyl-CoA and concomitant ATP synthesis by the mechanism of substrate level phosphorylation. ACD belongs to the protein superfamily of nucleoside diphosphate-forming acyl-CoA synthetases, which also include succinyl-CoA synthetases (SCSs). ACD differs from SCS in domain organization of subunits and in the presence of a second highly conserved histidine residue in the beta-subunit, which is absent in SCS. The influence of these differences on structure and reaction mechanism of ACD was studied with heterotetrameric ACD (alpha(2)beta(2)) from the hyperthermophilic archaeon Pyrococcus furiosus in comparison with heterotetrameric SCS. A structural model of P. furiosus ACD was constructed suggesting a novel spatial arrangement of the subunits different from SCS, however, maintaining a similar catalytic site. Furthermore, kinetic and molecular properties and enzyme phosphorylation as well as the ability to catalyze arsenolysis of acetyl-CoA were studied in wild type ACD and several mutant enzymes. The data indicate that the formation of enzyme-bound acetyl phosphate and enzyme phosphorylation at His-257alpha, respectively, proceed in analogy to SCS. In contrast to SCS, in ACD the phosphoryl group is transferred from the His-257alpha to ADP via transient phosphorylation of a second conserved histidine residue in the beta-subunit, His-71beta. It is proposed that ACD reaction follows a novel four-step mechanism including transient phosphorylation of two active site histidine residues:
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PMID:Reaction mechanism and structural model of ADP-forming Acetyl-CoA synthetase from the hyperthermophilic archaeon Pyrococcus furiosus: evidence for a second active site histidine residue. 1837 46

DltA, the D-alanine:D-alanyl carrier protein ligase responsible for the initial step of lipoteichoic acid D-alanylation in Gram-positive bacteria, belongs to the adenylation domain superfamily, which also includes acetyl-CoA synthetase and the adenylation domains of non-ribosomal synthetases. The two-step reaction catalyzed by these enzymes (substrate adenylation followed by transfer to the reactive thiol group of CoA or the phosphopantheinyl prosthetic group of peptidyl carrier proteins) has been suggested to proceed via large scale rearrangements of structural domains within the enzyme. The structures of DltA reported here reveal the determinants for D-Ala substrate specificity and confirm that the peptidyl carrier protein-activating domains are able to adopt multiple conformational states, in this case corresponding to the thiolation reaction. Comparisons of available structures allow us to propose a mechanism whereby small perturbations of finely balanced metastable structural states would be able to direct an ordered formation of non-ribosomal synthetase products.
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PMID:Crystal structure of DltA. Implications for the reaction mechanism of non-ribosomal peptide synthetase adenylation domains. 1878 82

Extracellular acidosis (low pH) is a tumor microenvironmental stressor that has a critical function in the malignant progression and metastatic dissemination of tumors. To survive under stress conditions, tumor cells must evolve resistance to stress-induced toxicity. Acyl-CoA synthetase 5 (ACSL5) is a member of the ACS family, which converts fatty acid to acyl-CoA. ACSL5 is frequently overexpressed in malignant glioma, whereas its functional significance is still unknown. Using retrovirus-mediated stable gene transfer (gain of function) and small interfering RNA-mediated gene silencing (loss of function), we show here that ACSL5 selectively promotes human glioma cell survival under extracellular acidosis. ACSL5 enhanced cell survival through its ACS catalytic activity. To clarify the genome-wide changes in cell signaling pathways by ACSL5, we performed cDNA microarray analysis and identified an ACSL5-dependent gene expression signature. The analysis revealed that ACSL5 was critical to the expression of tumor-related factors including midkine (MDK), a heparin-binding growth factor frequently overexpressed in cancer. Knockdown of MDK expression significantly attenuated ACSL5-mediated survival under acidic state. These results indicate that ACSL5 is a critical factor for survival of glioma cells under acidic tumor microenvironment, thus providing novel molecular basis for cancer therapy.
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PMID:Promotion of glioma cell survival by acyl-CoA synthetase 5 under extracellular acidosis conditions. 1880 31

The precise mechanisms by which omega-3 fatty acids improve fat metabolism are not completely understood. This study was designed to determine the effects of eicosapentaenoic acid (EPA) ethyl ester administration on the expression levels of several muscle, liver and adipose tissue genes involved in lipogenesis and fatty acid oxidation pathways. Male Wistar rats fed a standard diet (control animals) or a high-fat diet were treated daily by oral gavage with EPA ethyl ester (1g/kg) for 5 weeks. The high-fat diet caused a very significant increase in plasma cholesterol (P<.01) levels, which was reverted by EPA (P<.001). A significant decrease in circulating triglyceride levels (P<.05) was also observed in EPA-treated groups. EPA administration induced a significant down-regulation in some lipogenic genes such as muscle acetyl CoA carboxylase beta (ACC beta) (P<.05) and liver fatty acid synthase (FAS) (P<.05). Furthermore, a decrease in glucokinase (GK) gene expression was observed in EPA-treated animals fed a control diet (P<.01), whereas a significant increase in GK mRNA levels was found in groups fed a high-fat diet. On the other hand, no alterations in genes involved in beta-oxidation, such acetyl CoA synthase 4 (ACS4), acetyl CoA synthase 5 (ACS5) or acetyl CoA oxidase (ACO), were found in EPA-treated groups. Surprisingly and opposite to the expectations, a very significant decrease in the expression levels of liver PPARalpha (P<.01) was observed after EPA treatment. These findings show the ability of EPA ethyl ester treatment to down-regulate some genes involved in fatty acid synthesis without affecting the transcriptional activation of beta-oxidation-related genes.
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PMID:Down-regulation in muscle and liver lipogenic genes: EPA ethyl ester treatment in lean and overweight (high-fat-fed) rats. 1882 85

The discovery of the metallopeptide Ni(Cysteine-Glycine-Cysteine)(2-), Ni(CGC)(2-), in the A-cluster active site of Acetyl CoA Synthase has prompted the synthesis of many small molecule models which employ M(N(2)S(2)) complexes as metalloligands. In vitro studies have shown that nickel incorporates into the N(2)S(2) binding pocket even when copper is in the enzyme growth medium, while copper is preferentially taken up in the proximal site, displacing the catalytically active nickel. (Darnault, C.; Volbeda, A.; Kim, E.J.; Legrand, P.; Vernede, X.; Lindahl, P.A.; Fontecilla-Camps, J.C. Nat. Struct. Biol. 2003, 10, 271-279.) The work herein has been designed to address the chemical viability of copper(II) within the tripeptide N(2)S(2) ligand set. To this end, a series of CuN(2)S(2)(2-) complexes, the resin-bound, O-Cu(CGC)(2-) (A) and free Cu(CGC)(2-) (B) complexes, as well as Cu(ema)(2-) (C) and Cu(emi)(2-) (D) dianions, have been characterized by UV-vis, electron paramagnetic resonance (EPR), and electrospray ionization mass spectrometry (ESI-MS) spectroscopies, cyclic voltammetry (CV), and, where appropriate, X-ray diffraction studies, and compared to the Ni(II) congeners. EPR spectroscopic results have indicated that, in frozen N,N-dimethylformamide (DMF) solution, the copper complexes are distorted square planar structures with nitrogen and sulfur donors. This is consistent with X-ray diffraction measurements which also show copper(II) in a distorted square planar environment that is bereft of CuN(2)S(2)(2-) intermolecular interactions. Density-functional theory (DFT) calculations resulted in optimized structures that are consistent with crystallographic data and indicated highest occupied molecular orbital (HOMO)-singly occupied molecular orbital (SOMO) gaps of 5.01 and 4.68 eV for C and D, respectively. Optimized structures of Ni(ema)(2-) and Ni(emi)(2-) share the same basic characteristics as the copper(II) congeners. Electrochemical characterization of C and D resulted in a reversible Cu(III/II) couple at -1.20 V and - 1.40 V, respectively. Reactivity studies with Rh(CO)(2)(+) show similar donor capabilities for complexes A-D. Analysis of A shows that transmetalation does not occur. From competitive metal uptake studies on immobilized tripeptide it is concluded that the N(2)S(2)(4-) ligating unit has a slight preference for Cu(2+) over Ni(2+) and that the biosynthetic pathway responsible for constructing the distal site of ACS must be selective for nickel insertion or copper exclusion, or both.
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PMID:Chemical issues addressing the construction of the distal Ni[cysteine-glycine-cysteine]2- site of acetyl CoA synthase: why not copper? 1925 85

The acyl-AMP forming family of adenylating enzymes catalyze two-step reactions to activate a carboxylate with the chemical energy derived from ATP hydrolysis. X-ray crystal structures have been determined for multiple members of this family and, together with biochemical studies, provide insights into the active site and catalytic mechanisms used by these enzymes. These studies have shown that the enzymes use a domain rotation of 140 degrees to reconfigure a single active site to catalyze the two partial reactions. We present here the crystal structure of a new medium chain acyl-CoA synthetase from Methanosarcina acetivorans. The binding pocket for the three substrates is analyzed, with many conserved residues present in the AMP binding pocket. The CoA binding pocket is compared to the pockets of both acetyl-CoA synthetase and 4-chlorobenzoate:CoA ligase. Most interestingly, the acyl-binding pocket of the new structure is compared with other acyl- and aryl-CoA synthetases. A comparison of the acyl-binding pocket of the acyl-CoA synthetase from M. acetivorans with other structures identifies a shallow pocket that is used to bind the medium chain carboxylates. These insights emphasize the high sequence and structural diversity among this family in the area of the acyl-binding pocket.
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PMID:The 2.1 A crystal structure of an acyl-CoA synthetase from Methanosarcina acetivorans reveals an alternate acyl-binding pocket for small branched acyl substrates. 1954 69

Malonylation of an acyl carrier protein (ACP) by malonyl Coenzyme A-ACP transacylase (MCAT) is fundamental to bacterial fatty acid biosynthesis. Here, we report the structure of the Steptomyces coelicolor (Sc) fatty acid synthase (FAS) ACP and studies of its binding to MCAT. The carrier protein adopts an alpha-helical bundle structure common to other known carrier proteins. The Sc FAS ACP shows close structural homology with other fatty acid ACPs and less similarity with Sc actinorhodin (act) polyketide synthase (PKS) ACP where the orientation of helix I differs. NMR experiments were used to map the binding of ACP to MCAT. This data suggests that Sc FAS ACP interacts with MCAT through the negatively charged helix II of ACP, consistent with proposed models for ACP recognition by other FAS enzymes. Differential roles for residues at the interface are demonstrated using site-directed mutagenesis and in vitro assays. MCAT has been suggested, moreover, to participate in bacterial polyketide synthesis in vivo. We demonstrate that the affinity of the polyketide synthase ACP for MCAT is lower than that of the FAS ACP. Mutagenesis of homologous helix II residues on the polyketide synthase ACP suggests that the PKS ACP may bind to MCAT in a different manner than the FAS counterpart.
ACS Chem Biol 2009 Aug 21
PMID:Structure and malonyl CoA-ACP transacylase binding of streptomyces coelicolor fatty acid synthase acyl carrier protein. 1955 75


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