Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:5.99.1.3 (topoisomerase)
 9,911 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clerocidin (CL) is an effective topoisomerase II-poison, which has been shown to produce DNA depurination and strand breaks per se at the guanine (G) level. To elucidate the roles played by the different functional groups of CL in the reactivity towards nucleic acids, we investigated CL derivatives with key structural modifications. The derivatives were reacted with plasmid, single-/double-stranded DNA and isolated 2'-deoxy-guanosines (dG). We show here that an intact oxirane ring is essential to achieve DNA modification and depurination. Through HPLC/MS and MS/MS techniques we were able to unambiguously characterize adducts obtained by reacting isolated dG and single-/double-stranded DNA with the drugs, indicating beyond reasonable doubt that the structure of a typical adduct is formed by epoxide alkylation at N7 of G with subsequent loss of the pentose unit. Further, we showed that reduction of vicinal carbonyl functions affect drug activity to a large extent. Our findings demonstrate that the characteristic DNA-alkylating properties of CL arise from mutual action of the functional groups present in this molecule. Its oxidation state seems crucial to modulate the rates of reactivity by finely tuning the strain applied on the oxirane ring.
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PMID:Clerocidin alkylates DNA through its epoxide function: evidence for a fine tuned mechanism of action. 1293 Sep 66

The TOPRIM domain found in many nucleotidyl transferases contains a DxD motif involved in magnesium ion coordination for catalysis. Medium- to high-copy-number plasmid clones of Yersinia pestis topoisomerase I (YpTOP) with Asp-to-Asn substitution at the first aspartate residue (D117N) of this motif could not be generated in Escherichia coli without second-site mutation even when expression was under the control of the tightly regulated BAD promoter and suppressed by 2% glucose in the medium. Arabinose induction of a single-copy YpTOP-D117N mutant gene integrated into the chromosome resulted in approximately 10(5)-fold of cell killing in 2.5 h. Attempt to induce expression of the corresponding E. coli topoisomerase I mutant (EcTOP-D111N) encoded on a high-copy-number plasmid resulted in either loss of viability or reversion of the clone to wild type. High-copy-number plasmid clones of YpTOP-D119N and EcTOP-D113N with the Asn substitution at the second Asp of the TOPRIM motif could be stably maintained, but overexpression also decreased cell viability significantly. The Asp-to-Asn substitutions at these TOPRIM residues can selectively decrease Mg(2+) binding affinity with minimal disruption of the active-site geometry, leading to trapping of the covalent complex with cleaved DNA and causing bacterial cell death. The extreme sensitivity of the first TOPRIM position suggested that this might be a useful site for binding of small molecules that could act as topoisomerase poisons.
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PMID:Asp-to-Asn substitution at the first position of the DxD TOPRIM motif of recombinant bacterial topoisomerase I is extremely lethal to E. coli. 1901 70

The permanent draft genome sequence of Actinotignum schaalii DSM 15541T is presented. The annotated genome includes 2,130,987 bp, with 1777 protein-coding and 58 rRNA-coding genes. Genome sequence analysis revealed absence of genes encoding for: components of the PTS systems, enzymes of the TCA cycle, glyoxylate shunt and gluconeogensis. Genomic data revealed that A. schaalii is able to oxidize carbohydrates via glycolysis, the nonoxidative pentose phosphate and the Entner-Doudoroff pathways. Besides, the genome harbors genes encoding for enzymes involved in the conversion of pyruvate to lactate, acetate and ethanol, which are found to be the end products of carbohydrate fermentation. The genome contained the gene encoding Type I fatty acid synthase required for de novo FAS biosynthesis. The plsY and plsX genes encoding the acyltransferases necessary for phosphatidic acid biosynthesis were absent from the genome. The genome harbors genes encoding enzymes responsible for isoprene biosynthesis via the mevalonate (MVA) pathway. Genes encoding enzymes that confer resistance to reactive oxygen species (ROS) were identified. In addition, A. schaalii harbors genes that protect the genome against viral infections. These include restriction-modification (RM) systems, type II toxin-antitoxin (TA), CRISPR-Cas and abortive infection system. A. schaalii genome also encodes several virulence factors that contribute to adhesion and internalization of this pathogen such as the tad genes encoding proteins required for pili assembly, the nanI gene encoding exo-alpha-sialidase, genes encoding heat shock proteins and genes encoding type VII secretion system. These features are consistent with anaerobic and pathogenic lifestyles. Finally, resistance to ciprofloxacin occurs by mutation in chromosomal genes that encode the subunits of DNA-gyrase (GyrA) and topisomerase IV (ParC) enzymes, while resistant to metronidazole was due to the frxA gene, which encodes NADPH-flavin oxidoreductase.
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PMID:Draft genome sequence of Actinotignum schaalii DSM 15541T: Genetic insights into the lifestyle, cell fitness and virulence. 2921 46

Anthracyclines Doxorubicin, Epirubicin, Daunorubicin and Idarubicin are used to treat a variety of tumor types in the clinics, either alone or, most often, in combination therapies. While their cardiotoxicity is well known, the emergence of chemoresistance is also a major issue accounting for treatment discontinuation. Resistance to anthracyclines is associated to the acquisition of multidrug resistance conferred by overexpression of permeability glycoprotein-1 or other efflux pumps, by altered DNA repair, changes in topoisomerase II activity, cancer stemness and metabolic adaptations. This review further details the metabolic aspects of resistance to anthracyclines, emphasizing the contributions of glycolysis, the pentose phosphate pathway and nucleotide biosynthesis, glutathione, lipid metabolism and autophagy to the chemoresistant phenotype.
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PMID:Metabolic and non-metabolic pathways that control cancer resistance to anthracyclines. 3111 97