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

We examined the MLL translocation in two cases of infant AML with X chromosome disruption. The G-banded karyotype in the first case suggested t(X;3)(q22;p21)ins(X;11)(q22;q13q25). Southern blot analysis showed one MLL rearrangement. Panhandle PCR approaches were used to identify the MLL fusion transcript and MLL genomic breakpoint junction. SEPTIN6 from chromosome band Xq24 was the partner gene of MLL. MLL exon 7 was joined in-frame to SEPTIN6 exon 2 in the fusion transcript. The MLL genomic breakpoint was in intron 7; the SEPTIN6 genomic breakpoint was in intron 1. Spectral karyotyping revealed a complex rearrangement disrupting band 11q23. FISH with a probe for MLL confirmed MLL involvement and showed that the MLL-SEPTIN6 junction was on the der(X). The MLL genomic breakpoint was a functional DNA topoisomerase II cleavage site in an in vitro assay. In the second case, the karyotype revealed t(X;11)(q22;q23). Southern blot analysis showed two MLL rearrangements. cDNA panhandle PCR detected a transcript fusing MLL exon 8 in-frame to SEPTIN6 exon 2. MLL and SEPTIN6 are vulnerable to damage to form recurrent translocations in infant AML. Identification of SEPTIN6 and the SEPTIN family members hCDCrel and MSF as partner genes of MLL suggests a common pathway to leukaemogenesis.
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PMID:MLL-SEPTIN6 fusion recurs in novel translocation of chromosomes 3, X, and 11 in infant acute myelomonocytic leukaemia and in t(X;11) in infant acute myeloid leukaemia, and MLL genomic breakpoint in complex MLL-SEPTIN6 rearrangement is a DNA topoisomerase II cleavage site. 1209 48

New fluoroquinolones with higher antipneumococcal activity are considered promising in the treatment of respiratory tract infections. Still, their wide use in clinical practice is connected with possible selection and rapid distribution of the resistance, requiring constant monitoring. Development of resistance to fluoroquinolones results from step-wise accumulation of mutations in the genes of DNA-gyrase and topoisomerase IV, the mutations of the first step being not always accompanied by a significant increase of the MIC of the new fluoroquinolones. Therefore, to detect the first signs of the resistance development, it is necessary not only to detect the susceptibility of the circulating Streptococcus pneumoniae strains phenotypically, but also to detect the genetic changes. In the present study the minisequent reaction followed by detection of the reaction products by MALD-ToF mass-spectrometry was used to reveal the mutations in the genes of the fluoroquinolone targets of 38 S. pneumoniae strains with different levels of the resistance to ciprofloxacin, ofloxacin, levofloxacin and moxifloxacin. In the strains with high resistance to all the three fluoroquinolones (MIC 4-16 mcg/ml) there were detected mutations in GyrA (Ser81Tyr or Glu85Zys) and as well in ParC (Ser79Phe or Ser79Tyr). In the strains resistant to ofloxacin and ciprofloxacin (MIC 4-8 mcg/ml) with preserved susceptibility to levofloxacin and moxifloxacin, the mutations were detected only in GyrA (Ser114Gly). In the moderately resistant strains (MICs 4 and 2-4 mcg/ml respectively for ofloxacin and ciprofloxacin) there were detected the known mutations in ParC (Ser79Tyr or Ser79Phe or Asp83Tyr) and in GyrB (Glu475Lys) as well as the earlier not described mutations in ParE (ins Asn381a) and in Gyr B (Thr329Ala or Va1355Ile). The described method can be used in mass screening of S. pneumoniae strains for the presence of mutations in the genes of the fluoroquinolone targets.
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PMID:[MALDI-ToF mass-spectrometry in analysis of genetically determined resistance of Streptococcus pneumoniae to fluoroquinolones]. 1846 3

Anthocyanins and their aglycone anthocyanidins are pigmented flavonoids found in significant amounts in many commonly consumed foods. They exhibit a complex chemistry in aqueous solution, which makes it difficult to study their chemistry under physiological conditions. Here we used a gel electrophoresis assay employing supercoiled DNA plasmid to examine the ability of these compounds (1) to intercalate DNA, (2) to inhibit human topoisomerase I through both inhibition of plasmid relaxation activity (catalytic inhibition) and stabilization of the cleavable DNA-topoisomerase complex (poisoning), and (3) to inhibit or enhance oxidative single-strand DNA nicking. We found no evidence of DNA intercalation by anthocyan(id)ins in the physiological pH range for any of the compounds used in this study-cyanidin chloride, cyanidin 3-O-glucoside, cyanidin 3,5-O-diglucoside, malvidin 3-O-glucoside and luteolinidin chloride. The anthocyanins inhibited topoisomerase relaxation activity only at high concentrations (> 50 muM) and we could find no evidence of topoisomerase I cleavable complex stabilization by these compounds. However, we observed that all of the anthocyan(id)ins used in this study were capable of inducing significant oxidative DNA strand cleavage (nicking) in the presence of 1 mM DTT (dithiothreitol), while the free radical scavenger, DMSO, at concentrations typically used in similar studies, completely inhibited DNA nicking. Finally, we propose a mechanism to explain the anthocyan(id)in induced oxidative DNA cleavage observed under our experimental conditions.
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PMID:Anthocyanin Interactions with DNA: Intercalation, Topoisomerase I Inhibition and Oxidative Reactions. 1992 59