PMID:1330320

Citation	Adams, DE , Shekhtman, EM , Zechiedrich, EL , Schmid, MB and Cozzarelli, NR (1992) The role of topoisomerase IV in partitioning bacterial replicons and the structure of catenated intermediates in DNA replication. Cell 71:277-88
Abstract	Mutants in bacterial topoisomerase (topo) IV are deficient in chromosomal partitioning. To investigate the basis of this phenotype, we examined plasmid DNA topology in conditionally lethal topo IV mutants. We found that dimeric catenated plasmids accumulated in vivo after topo IV inhibition. The catenanes were supercoiled, contained from 2 to > 32 nodes, and were the products of DNA synthesis. Electron microscopy and recombination tests proved that the catenanes have the unique structure predicted for replication intermediates. These data provide strong evidence for a model in which unlinking of the double helix can occur in two stages during DNA replication and for the critical role of topo IV in the second stage. The interlocks in the catenanes appear to be sequestered from DNA gyrase, perhaps by compartmentalization in an enzyme complex dedicated to partitioning.
Links	PubMed
Keywords	Cell Compartmentation; DNA/chemistry; DNA Replication; DNA Topoisomerase IV; DNA Topoisomerases, Type I/physiology; Escherichia coli/genetics; Models, Biological; Replicon; Salmonella typhimurium/genetics
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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
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