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

In this study, the product of the CIT3 gene has been identified as a dual specificity mitochondrial citrate and methylcitrate synthase and that of the CIT1 gene as a specific citrate synthase. Recombinant Cit1p had catalytic activity only with acetyl-CoA whereas Cit3p had similar catalytic efficiency with both acetyl-CoA and propionyl-CoA. Deletion of CIT1 dramatically shifted the ratio of these two activities in whole cell extracts towards greater methylcitrate synthase. Deletion of CIT3 had little effect on either citrate or methylcitrate synthase activities. A Deltacit2Deltacit3 strain showed no methylcitrate synthase activity, suggesting that Cit2p, a peroxisomal isoform, may also have methylcitrate synthase activity. Although wild-type strains of Saccharomyces cerevisiae did not grow with propionate as a sole carbon source, deletion of CIT2 allowed growth on propionate, suggesting a toxic production of methylcitrate in the peroxisomes of wild-type cells. The Deltacit2Deltacit3 double mutant did not grow on propionate, providing further evidence for the role of Cit3p in propionate metabolism. (13)C NMR analysis showed the metabolism of 2-(13)C-propionate to acetate, pyruvate, and alanine in wild-type, Deltacit1 and Deltacit2 cells, but not in the Deltacit3 mutant. (13)C NMR and GC-MS analysis of pyruvate metabolism revealed an accumulation of acetate and of isobutanol in the Deltacit3 mutant, suggesting a metabolic alteration possibly resulting from inhibition of the lipoamide acetyltransferase subunit of the pyruvate dehydrogenase complex by propionyl-CoA. In contrast to Deltacit3, pyruvate metabolism in a Deltapda1 (pyruvate dehydrogenase E1 alpha subunit) mutant strain was only shifted towards accumulation of acetate.
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PMID:Functional comparison of citrate synthase isoforms from S. cerevisiae. 1757 Mar 35

Mitochondrial Targeting Sequences (MTSs) are responsible for trafficking nuclear-encoded proteins into mitochondria. Once entering the mitochondria, the MTS is recognized and cleaved off. Some MTSs are long and undergo two-step processing, as in the case of the human frataxin (FXN) protein (80aa), implicated in Friedreich's ataxia (FA). Therefore, we chose the FXN protein to examine whether nuclear-encoded mitochondrial proteins can efficiently be targeted via a heterologous MTS (hMTS) and deliver a functional protein into mitochondria. We examined three hMTSs; that of citrate synthase (cs), lipoamide deydrogenase (LAD) and C6ORF66 (ORF), as classically MTS sequences, known to be removed by one-step processing, to deliver FXN into mitochondria, in the form of fusion proteins. We demonstrate that using hMTSs for delivering FXN results in the production of 4-5-fold larger amounts of the fusion proteins, and at 4-5-fold higher concentrations. Moreover, hMTSs delivered a functional FXN protein into the mitochondria even more efficiently than the native MTSfxn, as evidenced by the rescue of FA patients' cells from oxidative stress; demonstrating a 18%-54% increase in cell survival; and a 13%-33% increase in ATP levels, as compared to the fusion protein carrying the native MTS. One fusion protein with MTScs increased aconitase activity within patients' cells, by 400-fold. The implications form our studies are of vast importance for both basic and translational research of mitochondrial proteins as any mitochondrial protein can be delivered efficiently by an hMTS. Moreover, effective targeting of functional proteins is important for restoration of mitochondrial function and treatment of related disorders.
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PMID:Heterologous mitochondrial targeting sequences can deliver functional proteins into mitochondria. 2777 40