Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.4.1.2 (acetyl-CoA carboxylase)
 2,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Holocarboxylase synthetase (HS) and biotinidase deficiencies have been identified as causes of biotin-responsive multiple carboxylase deficiency. Acetyl-CoA carboxylase (ACC) deficiency has been shown to occur in multiple carboxylase deficiency, and HS(-) fibroblasts are being employed to investigate compensatory regulatory responses in cells deficient in ACC. In previous studies, biotin starved HS(-) fibroblasts showed a reduced fatty acid content, an abnormal percentage composition of fatty acids, and a preservation of longer-chain fatty acid contents of cells. We herein ask whether the mutant cells show compensatory increases in the transport of longer-chain fatty acids from the medium into fibroblasts. In the present experiments there was no change in the uptake of arachidonate, palmitate or oleate following growth of mutant and control fibroblasts in (+) or (-) biotin conditions. Differential fatty acid uptake from the medium is therefore not a compensatory mechanism in HS(-) cells, and cannot account for the specific changes in fatty acid composition produced by biotin restriction.
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PMID:Fatty acid transport in multiple carboxylase deficiency fibroblasts. 212 77

The Saccharomyces cerevisiae gene BPL1 encodes the enzyme biotin:protein ligase (BPL), which is required for acetyl-CoA carboxylase (ACC) holoenzyme formation. Disruption of one of the two BPL1 alleles present in diploid cells results, upon sporulation, in a 2+:2(0) segregation of cell viability, with none of the two viable spores being BPL1 negative. In contrast to BPL1 deletants, BPL1 base-substitution mutants are potentially viable and may be isolated as long-chain-fatty-acid-requiring auxotrophs. In addition to ACC pyruvate carboxylase and an additional biotin-containing protein of unknown function fail to be biotinylated in BPL1-defective yeast mutants. In this study, one of these mutants, bpl1-C25/17, is shown to contain an amber stop codon at position 151 of the 689-amino-acid BPL sequence. In bpl1-C25/17 cells, de novo fatty acid synthesis is almost absent (< 2% of the wild type), while very-long-chain fatty acid (VLCFA) synthesis and, to some extent, medium-long-chain fatty acid elongation are still active. Hence, endogenous malonyl-CoA synthesis is reduced but not abolished by the translational stop mutation. A low rate of intact-BPL synthesis is accomplished in the mutant by occasional readthrough of the bpl1-C25/17 UAG nonsense triplet by normal yeast tRNA(Gln)(CAG). Correspondingly, ACC biotinylation is severely reduced though not completely absent in the two bpl1 mutants studied in this work. Residual BPL1 expression in bpl1-C25/17 cells is increased to a level allowing wild-type-like growth by transformation with high copy numbers of either the wild-type tRNA(Gln)(CAG) or the mutant bpl1-C25/17 genes. It is concluded that the lethality of BPL1 deletants is due to the lack of malonyl-CoA-dependent VLCFA synthesis and that the viability of distinct ACC-defective point mutants is due to their maintenance of a critical level of malonyl-CoA and, hence, VLCFA production. The residual capacity of malonyl-CoA synthesis, though, is inadequate to allow cytoplasmic bulk de novo fatty acid synthesis, nor does it support mutant growth on 13:0 as the only dietary fatty acid. ACC-defective mutants are respiratory deficient, which is attributed to the failure of mitochondrial fatty acid synthesis. Since lipoic acid levels of ACC1 and BPL1 mutants are essentially normal, an unknown product of mitochondrial fatty acid synthesis appears to be critically reduced in malonyl-CoA-deficient yeast cells.
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PMID:Pleiotropic phenotype of acetyl-CoA-carboxylase-defective yeast cells--viability of a BPL1-amber mutation depending on its readthrough by normal tRNA(Gln)(CAG). 968 62

Holocarboxylase synthetase (HCS) catalyzes the covalent attachment of biotin to five biotin-dependent carboxylases in human cells. Multiple carboxylase deficiency (MCD) is a life-threatening disease characterized by the lack of carboxylase activities because of deficiency of HCS activity. Here, we report the obligatory participation of HCS in the biotin-dependent stimulation of the level of HCS mRNA and those of acetyl-CoA carboxylase and the alpha subunit of propionyl-CoA carboxylase in human cells. Fibroblasts from patients with MCD are unable to increase HCS mRNA in response to biotin unless the vitamin concentration is raised 100-fold, in keeping with mutations that cause a reduced affinity for biotin by the mutant enzyme. The outcome is deficient synthesis of biotinyl-5'-AMP, the active form of the vitamin in the biotinylation reaction. HCS and carboxylase mRNA levels in normal and MCD fibroblasts and HepG2 cells can be restored by the addition of the cGMP analogue, 8-Br-cGMP, and can be abolished by the addition of inhibitors of the soluble form of guanylate cyclase. We propose a regulatory role for biotin in the control of HCS and carboxylase mRNA levels through a signaling cascade that requires HCS, guanylate cyclase, and cGMP-dependent protein kinase.
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PMID:Holocarboxylase synthetase is an obligate participant in biotin-mediated regulation of its own expression and of biotin-dependent carboxylases mRNA levels in human cells. 1195 85

The gene locus for acetyl-CoA carboxylase (ACC) involved in the primary metabolism was identified from the genomic library of Streptomyces toxytricini which produces a lipase inhibitor lipstatin. The 7.4 kb cloned gene was comprised of 5 ORFs including accD1, accA1, hmgL, fadST1, and stsF. In order to confirm the biochemical characteristics of AccA1, the gene was overexpressed in Escherichia coli cells, and the recombinant protein was purified through Ni2+ affinity chromatography. Because most of the expressed AccAl was biotinylated by host E. coli BirA in the presence of D-biotin, the non-biotinylated apo-AccA1 was purified after gene induction without D-biotin, followed by exclusion of holo-AccA1 using streptavidin beads. The separated apo-AccA1 was post-translationally biotinylated by S. toxytricini biotin apo-protein ligase (BPL) in a time- and enzyme-dependent manner. This result supports that this gene cluster of S. toxytricini encodes the functional ACC enzyme subunits to be biotinylated.
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PMID:Identification and characterization of acetyl-CoA carboxylase gene cluster in Streptomyces toxytricini. 1976 22

Holocarboxylase synthetase (HCS) is an essential enzyme that catalyzes the incorporation of biotin into apo carboxylase and the biotinylation of the four biotin-dependent carboxylases in the human cell. Deficiency of HCS results in decreased activity of these carboxylases and affects various metabolic processes. Despite the importance of this enzyme, the recognition mechanism of the biotinoyl domain by human HCS (hHCS) has remained unclear. We have developed a method to express hHCS in the baculovirus system and used it to purify catalytically active, full-length hHCS. NMR experiments on the biotinoyl domains from acetyl-CoA carboxylase indicate that when hHCS is added, it recognizes the MKM motif in human and in Escherichia coli with a preference to the human biotinoyl domain. In addition, hHCS can biotinylate the biotinoyl domains from human and E. coli acetyl-CoA carboxylase at similar rates compared to the E. coli biotin protein ligase, BirA, which reacts very slowly with the human biotinoyl domain. We propose that the hHCS has greater substrate acceptability, while the BirA has higher substrate specificity. These results provide insights into substrate recognition by hHCS, which can be distinguished from BirA in this respect.
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PMID:Substrate recognition characteristics of human holocarboxylase synthetase for biotin ligation. 1991 15

Holocarboxylase synthetase (HCS, human) and BirA (Escherichia coli) are biotin protein ligases that catalyze the ATP-dependent attachment of biotin to apocarboxylases. Biotin attachment occurs on a highly conserved lysine residue within a consensus sequence (Ala/Val-Met-Lys-Met) that is found in carboxylases in most organisms. Numerous studies have indicated that HCS and BirA, as well as biotin protein ligases from other organisms, can attach biotin to apocarboxylases from different organisms, indicating that the mechanism of biotin attachment is well conserved. In this study, we examined the cross-reactivity of biotin attachment between human and bacterial biotin ligases by comparing biotinylation of p-67 and BCCP87, the biotin-attachment domain fragments from human propionyl-CoA carboxylase and E. coli acetyl-CoA carboxylase, respectively. While BirA has similar biotinylation activity toward the two substrates, HCS has reduced activity toward bacterial BCCP87 relative to its native substrate, p-67. The crystal structure of a digested form of p-67, spanning a sequence that contains a seven-residue protruding thumb loop in BCCP87, revealed the absence of a similar structure in the human peptide. Significantly, an engineered "thumbless" bacterial BCCP87 could be biotinylated by HCS, with substrate affinity restored to near normal. This study suggests that the thumb loop found in bacterial carboxylases interferes with optimal interaction with the mammalian biotin protein ligase. While the function of the thumb loop remains unknown, these results indicate a constraint on specificity of the bacterial substrate for biotin attachment that is not itself a feature of BirA.
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PMID:Structural impact of human and Escherichia coli biotin carboxyl carrier proteins on biotin attachment. 2044 44