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)

The genes encoding the DNA gyrase A (GyrA) and B subunits (GyrB) of Methylovorus sp. strain SS1 were cloned and sequenced. gyrA and gyrB coded for proteins of 846 and 799 amino acids with calculated molecular weights of 94,328 and 88,714, respectively, and complemented Escherichia coli gyrA and gyrB temperature sensitive (ts) mutants. To analyze the role of type II topoisomerases in the intrinsic quinolone resistance of methylotrophic bacteria, the sequences of the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase and the C subunit (ParC) of topoisomerase IV (Topo IV) of Methylovorus sp. strain SS1, Methylobacterium extorquens AM1 NCIB 9133, Methylobacillus sp, strain SK1 DSM 8269, and Methylophilus methylotrophus NCIB 10515 were determined. The deduced amino acid sequences of the QRDRs of the ParCs in the four methylotrophic bacteria were identical to that of E. coli ParC. The sequences of the QRDR in GyrA were also identical to those in E. coli GyrA except for the amino acids at positions 83, 87, or 95. The Ser83 to Thr substitution in Methylovorus sp. strain SS1, and the Ser83 to Leu and Asp87 to Asn substitutions in the three other methylotrophs, agreed well with the minimal inhibitory concentrations of quinolones in the four bacteria, suggesting that these residues play a role in the intrinsic susceptibility of methylotrophic bacteria to quinolones.
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PMID:Molecular cloning of the DNA gyrase genes from Methylovorus sp. strain SS1 and the mechanism of intrinsic quinolone resistance in methylotrophic bacteria. 1640 55

Meiosis is a specialized form of cell division resulting in reproductive cells with a reduced, usually haploid, genome complement. A key step after premeiotic DNA replication is the occurrence of homologous recombination at multiple places throughout the genome, initiated with the formation of DNA double-strand breaks (DSBs) catalyzed by the topoisomerase-like protein Spo11. DSBs are distributed non-randomly in genomes, and understanding the mechanisms that shape this distribution is important for understanding how meiotic recombination influences heredity and genome evolution. Several methods exist for mapping where Spo11 acts. Of these, sequencing of Spo11-associated oligonucleotides (Spo11 oligos) is the most precise, specifying the locations of DNA breaks to the base pair. In this chapter we detail the steps involved in Spo11-oligo mapping in the SK1 strain of budding yeast Saccharomyces cerevisiae, from harvesting cells of highly synchronous meiotic cultures, through preparation of sequencing libraries, to the mapping pipeline used for processing the data.
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PMID:Sequencing Spo11 Oligonucleotides for Mapping Meiotic DNA Double-Strand Breaks in Yeast. 2834 90

During meiosis, the specialized cell division giving rise to gametes, numerous DNA double-strand breaks (DSBs) are introduced at multiple places throughout the genome by the topoisomerase-like protein Spo11. Homologous recombination, a highly conserved DSB repair pathway, is employed for their repair and ensures the formation of chiasmata and the proper segregation of homologous chromosomes. In the initial steps of recombination, end resection takes place, wherein Spo11 is endonucleolytically released and the 5'-terminal strands of each DSB are exonucleolytically processed, exposing the ssDNA necessary to identify a homologous repair template. DNA removed by DSB processing is reconstituted by DNA synthesis, which copies genetic information from the intact homologous template. We developed a next-generation sequencing assay, termed S1-seq, to study DNA end resection genome-wide at high-spatial resolution during yeast meiotic recombination. The assay relies on the fact that removal of the ssDNA tails of resected DSBs marks the position where resection stopped. Molecular features of resection are revealed by sequencing of these ssDNA-to-dsDNA junctions and comparison to high-resolution Spo11 DSB maps. We describe the experimental and computational methods for S1-seq as applied to meiosis in the SK1 strain of budding yeast Saccharomyces cerevisiae and discuss how it can also be applied to map DSBs and recombination intermediates.
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PMID:S1-seq Assay for Mapping Processed DNA Ends. 2952 37