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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Relationship of citrate synthase (EC 4.1.3.7) to the biosynthesis of glutamic acid was investigated by characterizing a new glutamic acid auxotroph FL100-D1 (glu 3) of Saccharomyces cerevisiae. Nutritional requirement of the mutant was satisfied by L-glutamic acid, L-glutamic acid peptide as well as several analogs of glutamic acid, but not by proline, ornithine, arginine, lysine or aspartic acid. The mutant was unable to utilize nonfermentable carbon sources, glycerol, acetate or lactate. Mutant glu3 unlike aconitaseless glutamic acid auxotroph glu 1, failed to accumulate 14C-citric acid in vivo from 1-14C-sodium acetate or U-14C-glutamic acid. Both spectrophotometric and radioactive assay procedures demonstrated a lack of significant citrate synthase activity in the dialysed extract of the mutant compared to the wild type strain. Mutant glu 3 complemented with glu 1 and glu 2 individually in vivo and exhibited a significant aconitase (EC 4.2.1.3) activity in vitro.
Mol Gen Genet 1975 Sep 08
PMID:Citrate synthaseless glutamic acid auxotroph of Saccharomyces cerevisiae. 110 43

We have isolated genomic clones complementing the aconitase-deficient strain (glu1-1) of Saccharomyces cerevisiae. Identification of the aconitase gene was established by enzymatic assays and molecular analyses. The corresponding mRNA has been characterized, and its direction of transcription has been determined. The complete nucleotide sequence revealed strong amino acid homologies with the sequences of some peptides isolated from the mammalian protein. Disruption of the gene by deletion-insertion led to glutamate auxotrophy. Expression of the aconitase gene was sensitive to glucose repression and was synergistically down regulated by glucose and glutamate.
Mol Cell Biol 1990 Jul
PMID:Molecular cloning of the yeast mitochondrial aconitase gene (ACO1) and evidence of a synergistic regulation of expression by glucose plus glutamate. 197 45

A method for gene transfer by means of interphase nuclei encapsulated within lipid membranes was developed. The method was based on passage of interphase nuclei through a layer of organic solvents containing phospholipids. Evidence was obtained indicating that the nuclei become surrounded by a protective phospholipid membrane: measurements of bound labelled or non-labelled phospholipids; decrease in the permeability of lipid-encapsulated nuclei for high molecular compounds; visualization by direct electron microscopy. Lipid-encapsulated nuclei of mink fibroblasts were used for transformation of mutant mouse LMTK- cells (deficient for thymidine kinase). The frequency of occurrence of HAT-resistant colonies/recipient cell was 1.9 X 10(-5). Biochemical analysis of 14 independent clones demonstrated that they all contained TK1 of mink origin. Analysis of 15 other biochemical markers located on 12 of the mink chromosomes revealed the activities of mink galactokinase (a syntenic marker) in 5 transformed clones, and that of mink aconitase-1 (the marker of mink chromosome 12) in 1 clone. No cytogenetically visible donor chromosomes were identified in the transformed clones. Nine transformed clones were tested for the stability of the TK+ phenotype; of these, the phenotype was expressed stably in 3 and unstably in 6. The method suggested is similar to the gene transfer procedure using total DNA. Its advantage is in ensuring efficient gene transfer and donor DNA integrity.
Mol Gen Genet 1985
PMID:Transfer of mink genes into mouse cells by means of isolated lipid-encapsulated nuclei. 386 8

Native x-ray diffraction data from single crystals of inactive aconitase from pig heart (Mr 80,000) have been collected on oscillation films to 2.7 A. Analysis shows that significant measurements of the anomalous scattering signal from the Fe-S cluster in the enzyme are available in the film data. The 5.0-A resolution anomalous difference Patterson function contains vectors for one Fe-S cluster (one aconitase molecule) per asymmetric unit in space group P2(1)2(1)2 with a = 173.6, b = 72.0, and c = 72.7 A. At 2.7-A resolution, the vector map is best interpreted by three Fe sites separated from each other by less than 3 A. The single-crystal diffraction data thus confirm the presence of a 3Fe center in the inactive form of aconitase. Furthermore, the data provide crystallographic evidence that 3Fe clusters exhibit structural heterogeneity. The Fe-Fe vectors cannot be interpreted in terms of 4-A distances as observed for the [3Fe-3S] cluster in Azotobacter ferrodoxin (Ghosh, D., O'Donnell, S., Furey, W., Robbins, A. H., and Stout, C. D. (1982) J. Mol. Biol. 158, 73-109). The results are therefore in agreement with a [3Fe-4S] cluster having 2.7-A Fe-Fe distances (Beinert, H., Emptage, M. H., Dreyer, J.-L., Scott, R. A., Hahn, J. E., Hodgson, K. O., and Thomson, A. J. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 393-396). However, the data do not unambiguously discriminate between this model and other 3Fe clusters having short Fe-Fe distances.
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PMID:Iron-sulfur cluster in aconitase. Crystallographic evidence for a three-iron center. 397 91

By means of metaphase chromosomes, the genes for mink thymidine kinase (TK) and hypoxanthine-phosphoribosyltransferase (HPRT) were transferred to mutant mouse cells, LMTK-, A9 (HPRT-) and teratocarcinoma cells, PCC4-aza 1 (HPRT-). Eighteen colonies were isolated from LMTK- (series A), 9 from A9 (series B) and none from PCC4-aza 1. The transformed clones contained mink TK or HPRT. Analysis of syntenic markers in series B demonstrated that one clone contained mink glucose-6-phosphate dehydrogenase (G6PD) and the other alpha-galactosidase; in series A, nine clones contained mink galactokinase (GALK) and six mink aldolase C (ALDC). Analysis of 12 asyntenic markers located in ten mink chromosomes showed the presence of only aconitase-1 (ACON1) (the marker of mink chromosome 12) in three clones of series A. The clones lost mink ACON1 between the fifth to tenth passages. Cytogenetic analysis established the presence of a fragment of mink chromosome 8 in eight clones of series A, but not in series B. The clones of series A lost mink TK together with mink GALK and ALDC during back-selection; in B, back-selection retained mink G6PD. No stable TK+ phenotype was detected in clones with a visible fragment of mink chromosome 8. Stability analysis demonstrated that about half of the clones of series B have stable HPRT+ phenotype whereas only three clones of series A have stable TK+ phenotype. It is suggested that the recipient cells, LMTK- and A9, differ in their competence for genetic transformation and integration of foreign genes.
Mol Gen Genet 1984
PMID:Cotransfer and phenotypic stabilisation of syntenic and asyntenic mink genes into mouse cells by chromosome-mediated gene transfer. 659 20

In the adipose tissue, besides fatty acid synthesis (FA-S) from glucose, which includes several mitochondrial steps, FA-S from glutamate has been demonstrated. FA-S from glutamate takes place in the cytosol through the backward pathway of Krebs cycle (BPKC) and is due to the sequential action of (1) alanine aminotransferase (ALT, EC 2.6.1.2), which is presence of pyruvate converts glutamate to oxoglutarate; (2) isocitrate dehydrogenase (NADP) (ICDH, EC 1.1.1.42), which converts oxoglutarate to isocitrate; (3) aconitate hydratase (ACO, EC 4.2.1.3), which transforms isocitrate to citrate: and (4) ATP citrate-lyase (ATP-CL, EC 4.1.3.8), which splits citrate to yield the acetyl-CoA needed for FA-S. We studied the enzymes involved in BPKC in homogenates of human adipose tissue. In normal subjects, the cytosolic activity (mumol/min/g protein) was: ALT = 10.3 +/- 1.1, ICDH = 29.5 +/- 2.8, ACO = 2.05 +/- 0.23, and ATP-CL = 1.2 +/- 0.2. Mitochondria contained less or no activity, values being 20, 9, 11, and 0% of total for ATL, ICDH, ACO, and ATP-CL, respectively. BPKC enzymes are more active than the enzymes limiting FA-S from glucose, i.e., phosphofructokinase (EC 2.7.1.11), pyruvate carboxylase (EC 6.4.1.1), and pyruvate dehydrogenase (EC 1.2.4.1). In the obese patients, cytosolic ALT and ATP-CL were increased (12.9 +/- 0.7, P < 0.05, and 2.28 +/- 0.27, P < 0.01, respectively) compared to normal, while ICDH was not changed (ACO could not be studied). Similar changes were obtained by expressing enzyme activity per fat cell number.(ABSTRACT TRUNCATED AT 250 WORDS)
Biochem Mol Med 1995 Feb
PMID:Fatty acid synthesis from glutamate in the adipose tissue of normal subjects and obese patients: an enzyme study. 755 12

Mitochondria (m-)aconitase is a rate-limiting regulatory enzyme in prostate epithelial cells which minimizes citrate oxidation by these cells. This unique metabolite characteristic is responsible for the ability of the prostate to accumulate and secrete extraordinarily high levels of citrate. Testosterone is a major regulator of prostate growth and function, and stimulates citrate oxidation. Therefore, an important action of testosterone might be its stimulation of m-aconitase in prostate epithelial cells. Studies were conducted with rat ventral prostate (VP) epithelial cells to establish the effect of testosterone on the level of m-aconitase and corresponding citrate oxidation. Physiological concentrations (10(-7)-10(-10) M) of testosterone in vitro markedly increased the level of m-aconitase in freshly prepared isolated prostate epithelial cells. This increase was apparent within 3 h of exposure to the hormone. The stimulatory effect of testosterone on m-aconitase was abolished by actinomycin D and by cycloheximide. Both the level of m-aconitase enzyme and the level of m-aconitase activity were similarly increased by testosterone treatment. Correspondingly, testosterone increased the rate of mitochondrial citrate oxidation while having no effect on the rate of isocitrate oxidation, thereby demonstrating that the action of testosterone is specifically targeted at the m-aconitase reaction. In vivo studies revealed that castration markedly decreased and testosterone administration increased the m-aconitase level of prostate epithelial cells. In contrast, neither liver nor kidney m-aconitase level was altered by castration. These studies demonstrate that testosterone regulates the biosynthesis of m-aconitase in prostate epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1995 Jul
PMID:Testosterone stimulates the biosynthesis of m-aconitase and citrate oxidation in prostate epithelial cells. 758 84

We have cloned a nuclear gene from the marine red alga Gracilaria verrucosa that encodes the complete 779 amino-acid mitochondrial aconitase (m-ACN), the first characterized from a photosynthetic organism. The N-terminal 28 deduced amino acids are predicted to constitute the mitochondrial transit peptide, the first described from a red alga. Putative transcriptional cis-acting elements were identified in the upstream untranslated region. The G. verrucosa m-ACN gene (m-ACN) is present in a single copy and is located ca. 1.5 kb upstream from the single-copy polyubiquitin gene. The single spliceosomal intron is located near the 5' end of the region encoding the mature m-ACN in precisely the same location and phase as intron 2 in Caenorhabditis elegans m-ACN; sequences at its 3' and 5' splice junctions and at the predicted lariat branch point conform well to the eukaryote consensus sequences. Multiple protein-sequence alignment of m-ACN, bacterial aconitase (b-ACN) and iron-responsive element-binding protein (IRE-BP), and phylogenetic analyses, revealed that m-ACN does not share a recent common ancestry with either b-ACN or IRE-BP.
Plant Mol Biol 1995 Jul
PMID:Characterization of the nuclear gene encoding mitochondrial aconitase in the marine red alga Gracilaria verrucosa. 764 96

We have presently investigated the putative protective role of hemin against the inhibitory actions of the cytokine interleukin-1 beta (IL-1 beta) on isolated rat pancreatic islets. For this purpose, islets were isolated from adult rats, pre-cultured for 3-7 days in RPMI 1640 medium + 10% fetal calf serum and then exposed to IL-1 beta (5 ng/ml), hemin for 1, 7 or 24 h after which islet nitrite production, aconitase activity, glucose oxidation rates, glucose-stimulated insulin release and medium insulin accumulation were determined. It was found that hemin did not prevent IL-1 beta induced nitrite production. On the other hand, hemin partially counteracted the IL-1 beta induced decrease in aconitase activity, glucose oxidation, insulin release and medium insulin accumulation. This protective effect was present at a hemin concentration of 10 microM and most pronounced at 100 microM. Furthermore, hemin induced the synthesis of a 31 kDa protein, which was shown to be heme oxygenase as demonstrated by Western blot analysis. Finally, the protease inhibitor N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK), which protects against IL-1 beta by decreasing nitric oxide production, was found to act additively in combination with hemin in alleviating the IL-1 beta effects. It is proposed that the beneficial effects of hemin against IL-1 beta could be related to scavenging of nitric oxide and/or an increased resistance to nitric oxide production.
Mol Cell Endocrinol 1994 Jul
PMID:Protective action by hemin against interleukin-1 beta induced inhibition of rat pancreatic islet function. 795 87

Crystal structures of mitochondrial aconitase with the inhibitors trans-aconitate and nitrocitrate bound to the [4Fe-4S] cluster have been solved and refined at 2.05 A resolution with R-factors of 0.168 and 0.172, respectively. Crystallization of aconitase with the substrates citrate and cis-aconitate has not been possible because the enzyme turns over and selects enzyme with isocitrate bound into the crystal lattice. Therefore we have analyzed crystal structures of the enzyme complexed with inhibitor analogs of these two substrates. The structure with nitrocitrate bound provides a model for citrate binding. The structure with trans-aconitate bound provides a model for cis-aconitate binding in two ways: Fe4 of the [4Fe-4S] cluster is five-coordinate and the carbon at the C beta position is trigonal. These results allow the model for the reaction mechanism to be extended to all three natural substrates of aconitase. The results support a model in which citrate and isocitrate form similar chelate structures related by 180 degrees rotation about the C alpha-C beta bond while the intermediate cis-aconitate binds in either of two ways (citrate mode or isocitrate mode). In both inhibitor complexes a H2O molecule is also bound to Fe4. In the structure with nitrocitrate bound, partial occupancy of sulfate in the active site is observed accompanied by hydroxyl binding to Fe4. Comparison of the structures with isocitrate, trans-aconitate, nitrocitrate and sulfate bound reveals preferred orientations for the three types of oxygens ligated to Fe4 (carboxyl, hydroxyl and H2O) supporting the proposed roles for His101, Asp165 and His167 in the catalytic mechanism.
J Mol Biol 1994 Apr 08
PMID:Crystal structures of aconitase with trans-aconitate and nitrocitrate bound. 815 4


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