PMID:23913317

Citation	Szafran, M, Skut, P, Ditkowski, B, Ginda, K, Chandra, G, Zakrzewska-Czerwińska, J and Jakimowicz, D (2013) Topoisomerase I (TopA) is recruited to ParB complexes and is required for proper chromosome organization during Streptomyces coelicolor sporulation. J. Bacteriol. 195:4445-55
Abstract	Streptomyces species are bacteria that resemble filamentous fungi in their hyphal mode of growth and sporulation. In Streptomyces coelicolor, the conversion of multigenomic aerial hyphae into chains of unigenomic spores requires synchronized septation accompanied by segregation of tens of chromosomes into prespore compartments. The chromosome segregation is dependent on ParB protein, which assembles into an array of nucleoprotein complexes in the aerial hyphae. Here, we report that nucleoprotein ParB complexes are bound in vitro and in vivo by topoisomerase I, TopA, which is the only topoisomerase I homolog found in S. coelicolor. TopA cannot be eliminated, and its depletion inhibits growth and blocks sporulation. Surprisingly, sporulation in the TopA-depleted strain could be partially restored by deletion of parB. Furthermore, the formation of regularly spaced ParB complexes, which is a prerequisite for proper chromosome segregation and septation during the development of aerial hyphae, has been found to depend on TopA. We hypothesize that TopA is recruited to ParB complexes during sporulation, and its activity is required to resolve segregating chromosomes.
Links	PubMed PMC3807468 Online version:10.1128/JB.00798-13
Keywords	Chromosome Segregation/physiology; Chromosomes, Bacterial/genetics; Cloning, Molecular; DNA Primase/genetics; DNA Primase/metabolism; DNA Topoisomerases, Type I/genetics; DNA Topoisomerases, Type I/metabolism; DNA, Superhelical; Gene Deletion; Gene Expression Regulation, Bacterial/physiology; Gene Expression Regulation, Enzymologic/physiology; Nucleoproteins/metabolism; Spores, Bacterial; Streptomyces coelicolor/genetics; Streptomyces coelicolor/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
STRCO:TOP1		GO:0007059: chromosome segregation	ECO:0000315:		P		In figure 4, a wild type S. coelicolor (M145)and two examples of a mutant S. coelicolor without TopA proteins (PS01) were stained to show organization of cell walls (blue) and DNA (red) during sporulation. In the mutant cells, both the DNA and cell wall showed no order, as the red and blue colors were smeared throughout the cell. This meant that there is no chromosome condensing or separating. But in the wild type, the DNA is packed between evenly spaced cell walls. This means that, in the presence of TopA, chromosomes were condensed and segregated into different segments along the cell, ready for sporulation.	complete CACAO 13173

References

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