An increase in negative supercoiling in bacteria reveals topology-reacting gene clusters and a homeostatic response mediated by the DNA topoisomerase I gene.
Nucleic Acids Res, 2016/09/06;44(15):7292-303.
Ferrándiz MJ[1], Martín-Galiano AJ[1], Arnanz C[1], Camacho-Soguero I[1], Tirado-Vélez JM[1], de la Campa AG[2]
Affiliations
PMID: 27378778DOI: 10.1093/nar/gkw602
Impact factor: 19.16
Abstract
We studied the transcriptional response to an increase in DNA supercoiling in Streptococcus pneumoniae by using seconeolitsine, a new topoisomerase I inhibitor. A homeostatic response allowing recovery of supercoiling was observed in cells treated with subinhibitory seconeolitsine concentrations. Supercoiling increases of 40.7% (6 μM) and 72.9% (8 μM) were lowered to 8.5% and 44.1%, respectively. Likewise, drug removal facilitated the recovery of cell viability and DNA-supercoiling. Transcription of topoisomerase I depended on the supercoiling level. Also specific binding of topoisomerase I to the gyrase A gene promoter was detected by chromatin-immunoprecipitation. The transcriptomic response to 8 μM seconeolitsine had two stages. An early stage, associated to an increase in supercoiling, affected 10% of the genome. A late stage, manifested by supercoiling recovery, affected 2% of the genome. Nearly 25% of the early responsive genes formed 12 clusters with a coordinated transcription. Clusters were 6.7-31.4 kb in length and included 9-22 responsive genes. These clusters partially overlapped with those observed under DNA relaxation, suggesting that bacteria manage supercoiling stress using pathways with common components. This is the first report of a coordinated global transcriptomic response that is triggered by an increase in DNA supercoiling in bacteria.
MeSH terms
Benzodioxoles; DNA Gyrase; DNA Topoisomerases, Type I; DNA, Bacterial; DNA, Superhelical; Gene Expression Regulation, Bacterial; Genes, Bacterial; Homeostasis; Microbial Viability; Multigene Family; Phenanthrenes; Streptococcus pneumoniae; Transcription, Genetic; Transcriptome
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