Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rhizobium species elicit the formation of nitrogen-fixing root nodules through a complex interaction between bacteria and plants. Various bacterial genes involved in the nodulation and nitrogen-fixation processes have been described and most have been localized on the symbiotic plasmids (pSym). We have found a gene encoding citrate synthase on the pSym plasmid of Rhizobium tropici, a species that forms nitrogen-fixing nodules on the roots of beans (Phaseolus vulgaris) and trees (Leucaena spp.). Citrate synthase is a key metabolic enzyme that incorporates carbon into the tricarboxylic acid cycle by catalysing the condensation of acetyl-CoA and oxaloacetic acid to form citrate. R. tropici pcsA (the plasmid citrate synthase gene) is closely related to the corresponding genes of Proteobacteria. pcsA inactivation by a Tn5-mob insertion causes the bacteria to form fewer nodules (30-50% of the original strain) and to have a decreased citrate synthase activity in minimal medium with sucrose. A clone carrying the pcsA gene complemented all the phenotypic alterations of the pcsA mutant, and conferred Rhizobium leguminosarum bv. phaseoli (which naturally lacks a plasmid citrate synthase gene) a higher nodulation and growth capacity in correlation with a higher citrate synthase activity. We have also found that pcsA gene expression is sensitive to iron availability, suggesting a possible role of pcsA in iron uptake.
Mol Microbiol 1994 Jan
PMID:Nodulating ability of Rhizobium tropici is conditioned by a plasmid-encoded citrate synthase. 817 Mar 93

The aim of this work was to study in the adult rat heart the effect of modifications of fatty acid (FA) supply on the content of cytoplasmic fatty acid-binding protein (H-FABPc). To modify the amount of circulating lipids, three different treatments were chosen: (i) an hypolipidemic treatment with Clofibrate, administered daily through a gastric tube at a dose of 250 mg/kg per day for one week, (ii) a continuous intravenous infusion of 20% Intralipid, a fat emulsion, for one week at a dose of 96 ml/kg per day, and (iii) a normobaric hypoxia exposure (pO2 = 10%) for three weeks. At the end of each treatment plasma lipids, myocardial H-FABPc content and the activities of three key enzymes (citrate synthase, CS, fructose-6-phosphate kinase, FPK and hydroxy-acyl CoA-dehydrogenase, HAD) were assessed. With each of the three treatments a decrease of plasma cholesterol and phospholipid levels was observed. Plasma FA concentration increased with Intralipid infusion and decreased with chronic hypoxia. The heart H-FABPc content was increased by 20% with Clofibrate, decreased by 20% with chronic hypoxia and remained unaltered upon Intralipid treatment. The induced changes in H-FABPc content were not related directly to changes in plasma lipid levels. CS activity was slightly decreased in the hypoxia group, FPK activity decreased in the Clofibrate group, and HAD activity decreased in the Intralipid group. Among the various groups heart H-FABPc content was related to HAD activity. In conclusion, the H-FABPc content of adult rat heart appears responsive to changes in plasma lipid levels.
Mol Cell Biochem
PMID:Modulation of fatty acid-binding protein content of adult rat heart in response to chronic changes in plasma lipid levels. 823 51

Since insect flight muscles are among the most active muscles in nature, their extremely high rates of fuel supply and oxidation pose interesting physiological problems. Long-distance flights of species like locusts and hawkmoths are fueled through fatty acid oxidation. The lipid substrate is transported as diacylglycerol in the blood, employing a unique and efficient lipoprotein shuttle system. Following diacyglycerol hydrolysis by a flight muscle lipoprotein lipase, the liberated fatty acids are ultimately oxidized in the mitochondria. Locusta flight muscle cytoplasm contains an abundant fatty acid-binding protein (FABP). The flight muscle FABP of Locusta migratoria is a 15 kDa protein with an isoelectric point of 5.8, binding fatty acids in a 1:1 molar stoichiometric ratio. Binding affinity of the FABP for long-chain fatty acids (apparent dissociation constant Kd = 5.21 +/- 0.16 microM) is however markedly lower than that of mammalian FABPs. The NH2-terminal amino acid sequence shares structural homologies with two insect FABPs recently purified from hawkmoth midgut, as well as with mammalian FABPs. In contrast to all other isolated FABPs, the NH2 terminus of locust flight muscle FABP appeared not to be acetylated. During development of the insect, a marked increase in fatty acid binding capacity of flight muscle homogenate was measured, along with similar increases in both fatty acid oxidation capacity and citrate synthase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem
PMID:Role of fatty acid-binding protein in lipid metabolism of insect flight muscle. 823 56

Recent studies indicate that the mucosa of the urinary bladder may play a major role in the maintenance of normal bladder function. The mucosal surface of the urinary bladder serves as a protective layer against the irritative solutes found in the urine. The integrity of this barrier can be broken by overdistension, anoxia, detergents, alcohols, bacterial infection and by contact with agents to which the mucosa has been sensitized. In view that both anoxia and ischemia can mediate a breakdown in the role of the mucosal layer as a permeability barrier, it is reasonable to assume that this function is dependent on cellular metabolism. As an initial investigation we have compared a variety of biochemical and metabolic parameters between the mucosal layer (consisting of the lamina propria, urothelium, and any connective tissue and vascular tissue within this layer); and the muscularis layer. The results of these studies demonstrated that the rate of glucose metabolism to lactic acid (LA) of the mucosa was more than three-fold greater than that of the smooth muscle. The rate of CO2 production of the mucosa was 60% greater than that of the unstimulated smooth muscle. The maximal activity of the mitochondrial enzyme citrate synthase was significantly greater in the mucosa than in the smooth muscle, however, the activity of malate dehydrogenase was similar for both tissues. The maximal activity of the cytosolic enzyme creatine kinase was more than two-fold greater in the bladder smooth muscle than in the mucosa; although the affinities of the creatine kinase isoforms of the mucosa were significantly greater than those of the muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1993 Aug 11
PMID:Metabolic studies on rabbit bladder smooth muscle and mucosa. 826 70

The human leukaemic cell line HL60 undergoes differentiation to granulocyte-like cells in response to dimethylsulphoxide (DMSO). The rates of glucose and glutamine utilization were studied in HL60 cells that were either undifferentiated or fully differentiated by 9 days exposure to DMSO. Differentiation did not alter the rate of utilization of exogenous glucose, approximately 75% of which was converted to lactate in each case. The activities of hexokinase, phosphofructokinase, pyruvate kinase and citrate synthase were similarly unaffected. In contrast, the activity of the oxidative segment of the pentose-phosphate pathway was enhanced by differentiation, and no glycogen synthase activity could be detected. These observations are consistent with the significantly lower content of glycogen, the increased activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and the increased oxidation of [1-14C] glucose relative to [6-14C] glucose in the differentiated cells. Glucose utilization was depressed by exogenous glutamine but, at the same time, glutamine utilization was enhanced by glucose in both cell types; these reciprocal effects were more pronounced in the undifferentiated HL60 cells. Glucose utilization may be depressed in the presence of glutamine as a result of the allosteric inhibition of a rate-limiting step of glycolysis (eg. phosphofructokinase). In spite of having glutaminase activity twice that of their differentiated counterparts, the uptake of glutamine by undifferentiated HL60 cells was low, especially when it was the sole substrate. The stimulation of glutaminolysis by glucose may be due to activation of mitochondrial glutamine transport. A large proportion of the glutamine utilized by both cells contributed to a net accumulation of glutamate, aspartate and alanine, whilst up to 35% was oxidized to CO2. In contrast, almost all of the glucose utilized was converted to lactate and very little was oxidized. The high rates of glycolysis and glutaminolysis observed before and after differentiation may not contribute primarily to energy production but may supply, in undifferentiated cells, substrates for biosynthetic processes that generate nucleic acid precursors or, in the case of differentiated cells which synthesize reactive oxygen intermediates, substrates that maintain NADP in a reduced state.
Biochem Mol Biol Int 1993 Apr
PMID:Glycolytic, glutaminolytic and pentose-phosphate pathways in promyelocytic HL60 and DMSO-differentiated HL60 cells. 833 14

Single crystals of citrate synthase from the Archaeon Thermoplasma acidophilum were obtained in two forms using the hanging drop vapour diffusion method and polyethylene glycol 3350 as precipitant. Type 1 crystals belong to the orthorhombic space group P222(1), with unit cell dimensions a = 80.9 A, b = 103.8 A, c = 98.3 A and one dimer in the asymmetric unit. Type 2 crystals belong to the monoclinic space group P2(1), with unit cell dimensions a = 53.8 A, b = 173.8 A, c = 86.7 A and beta = 97.1 degrees and two dimers in the asymmetric unit.
J Mol Biol 1993 Jul 05
PMID:Crystallization and preliminary crystallographic study of citrate synthase from the thermophilic Archaeon Thermoplasma acidophilum. 833 68

The effects of chronic embryonic ethanol exposure were evaluated in chick ventricular muscle. Ethanol treatments were administered on embryonic days 11, 13, 15, and 17 and chicks were sacrificed at various time points following treatments. Fluctuations in embryonic blood ethanol levels were examined following treatments. Developmental increases in the activities of mitochondrial enzymes, cytochrome oxidase (CO) and citrate synthase (CS), were observed. Ethanol exposure resulted in a depression in CO activity, but not CS activity. Since, a maximal depression in CO activity was seen with ethanol treatments of 75 mg/100 g, this dosing paradigm was adopted for subsequent experiments. A tissue-specific effect of ethanol was demonstrated as CO activity was unchanged in atrial, liver, pectoralis, and brain tissues. The role of mitochondrial DNA replication and transcription during the developmental up-regulation and ethanol-induced down-regulation of CO activity was evaluated using a cDNA probe for cytochrome oxidase subunit III (COIII). The relative levels of COIII mRNA and mitochondrial DNA (cpm/mg protein) decreased by 3-fold and 4-fold, respectively, across the developmental time course, while CO activity increased by 3.5-fold. Therefore, increases in mitochondrial DNA and mitochondrial mRNA transcripts are unlikely to be responsible for the developmentally-regulated increases in CO activity. Similarly, embryonic ethanol exposure failed to elicit alterations in COIII mRNA levels, indicating that the ethanol-induced depression in CO activity was not transcriptionally regulated. However, ventricular mitochondrial DNA concentrations were elevated in ethanol-treated embryos, indicating that ethanol-exposure either directly or indirectly induces mitochondrial DNA replication.
J Mol Cell Cardiol 1993 Feb
PMID:Ventricular mitochondrial gene expression during development and following embryonic ethanol exposure. 838 53

Inheritance of mitochondrial DNA (mtDNA) in Saccharomyces cerevisiae is usually biparental. Pedigree studies of zygotic first buds indicate limited mixing of wild-type (p+) parental mtDNAs: end buds are frequently homoplasmic for one parental mtDNA, while heteroplasmic and recombinant progeny usually arise from medial buds. In crosses involving certain petites, however, mitochondrial inheritance can be uniparental. In this study we show that mitochondrial sorting can be influenced by the parental mtDNAs and have identified intermediates in the process. In crosses where mtDNA mixing is limited and one parent is prelabeled with the matrix enzyme citrate synthase 1 (CS1), the protein freely equilibrates throughout the zygote before the first bud has matured. Furthermore, if one parent is p0 (lacking mtDNA), mtDNA from the p+ parent can also equilibrate; intracellular movement of mtDNA is unhindered in this case. Surprisingly, in zygotes from a p0 CS1+ x p+ CS1- cross, CS1 is quantitatively translocated to the p+ end of the zygote before mtDNA movement; subsequently, both components equilibrate throughout the cell. This initial vectorial transfer does not require respiratory function in the p+ parent, although it does not occur if that parent is p-. Mouse dihydrofolate reductase (DHFR) present in the mitochondrial matrix can also be vectorially translocated, indicating that the process is general. Our data suggest that in zygotes mtDNA movement may be separately controlled from the movement of bulk matrix constituents.
Mol Biol Cell 1993 Jan
PMID:Patterns of mitochondrial sorting in yeast zygotes. 844 7

It was previously shown that polyunsaturated and saturated fatty acid rich diets affected metabolic and functional changes in macrophages and a variety of immune tissues (thymus, mesenteric lymph nodes and spleen). This study reports metabolic and functional changes in peritoneal macrophages and lymphocytes of Walker-256 ascites cell tumour-bearing rats which were fed (a) normal balanced diet (3% fat), (b) diet enriched (15% fat) with polyunsaturated fatty acids or (c) diet fortified (15% fat) with saturated fatty acids. Neither of the fatty acid enriched diets affected macrophage migration following tumour cell implantation and ascitic cell growth. However both of these fortified fatty acid regimes enhanced the production of H2O2 by macrophages and lymphocytes. The maximum catalytic capacities of hexokinase, glutaminase, glucose-6-phosphate dehydrogenase and glutathione peroxidase were measured in resident and tumour activated macrophages and lymphocytes obtained from rats fed the three fatty acid dietary regimes during seven days of tumour ascites cell growth. Tumour growth caused an increase in the activities of all of the above enzymes in macrophages irrespective of the fatty acid composition of the diet and notably decreased, independent of dietary fatty acid composition, the activities of the enzymes in lymphocytes. Only glutaminase activity in the lymphocytes of tumour bearing animals fed an unsaturated fatty acid-rich diet was not reduced, but was increased by 78%. Moreover macrophages from control rats fed an enriched polyunsaturated fatty acid diet had increased hexokinase activity (21%), decreased glutaminase (48%) and citrate synthase (decreased 41%) relative to the activities of these enzymes in macrophages of animals maintained on a balanced fatty acid diet. The feeding of both fatty acid rich diets did not modify the pattern of lymphocyte responses during the growth of tumour cells in these animals. None of the fatty acid diets modified the growth rate nor the yield of tumour cells in the peritoneal cavity.
Biochem Mol Biol Int 1993 Jan
PMID:Effects of various dietary fatty acids on enzyme activities of carbohydrate and glutamine metabolism and the metabolic response of lymphocytes and macrophages during Walker-256 ascites cell tumour growth in rats. 849 May 66

During the fetal and suckling periods of mammalian development, the mother serves as the sole nutritional source for the offspring. As such, the quality of the maternal diet effects growth and development of the offspring during these periods. This study sought to determine if a maternal vitamin D deficiency altered the well characterized development of the neonatal heart. Weaned rat pups (21-day-old) were obtained from mothers who had consumed either a vitamin D-supplemented diet (3000 IU of vitamin D/kg) or a low vitamin D diet (< 200 IU of vitamin D/kg) prior to becoming pregnant and throughout pregnancy and suckling. These pups were sacrificed, hearts excised, and the hearts biochemically analysed for metabolic and contractile protein properties. The pups of dams fed the low vitamin D diet were slightly hypocalcemic relative to those on the supplemented diet (2.28 v 2.41 mumol/l, P < 0.05), had significantly lower body weights (43 v 55 g), heart weights (143 v 174 mg), citrate synthase activity (106 v 147 mumol g-1 min-1), and 3-hydroxyacyl CoA dehydrogenase activity (59 v 91 mumol g-1 min-1). Hexokinase activity (1.98 v 2.02 mumol g-1 min-1), and the distribution of cardiac myosin among its three isoforms (> 85% V1), were unaffected by this dietary deficiency, however myofibrillar protein content was approximately 15% lower in the experimental hearts. These data demonstrate that maternal consumption of a low vitamin D diet results in a general but significant slowing of neonatal cardiac development.
J Mol Cell Cardiol 1995 Jun
PMID:Maternal consumption of a low vitamin D diet retards metabolic and contractile development in the neonatal rat heart. 853 Dec 6


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