Decatenation
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General Description
Replication of a closed circular chromosome results in two topologically-linked daughter chromosomes, similar to links of a chain. Decatenation is defined as the process of separating this physical linkage.
Components
The main decatenase in the cell is Topoisomerase IV. Topo IV is a heterotetramer consisting of 2 monomers of ParE and 2 monomers of ParC.
Function
Regulation
There is spatial and temporal regulation of the decatenation process. The ParC component of the active enzyme is thought to associate with the DNA holoenzyme via an interaction with DnaX while ParE remains free in the cell. After replication of the DNA is completed and the holoenzyme dissociates, ParC is then free to interact with ParE, forming the competent decatenase close to the chromosomal terminus[1].
The CTD of FtsK has been shown to stimulate not only Topo IV's decatenation activity, but also its positive scDNA relaxation activity[2].
Cell Biology
Topo IV is thought to act at dif.
Experimental Resources
Comparison with other organisms
Notes
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Chromosomes may also be unlinked with:
- several rounds of site-specific recombination by XerCD-dif or Cre-loxP in vivo, requiring KOPS-guided DNA translocation by FtsK[3]
- Topo III if nicks are present
References
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- ↑ Espeli, O et al. (2003) Temporal regulation of topoisomerase IV activity in E. coli. Mol. Cell 11 189-201 PubMed
- ↑ Bigot, S & Marians, KJ (2010) DNA chirality-dependent stimulation of topoisomerase IV activity by the C-terminal AAA+ domain of FtsK. Nucleic Acids Res. 38 3031-40 PubMed
- ↑ Grainge, I et al. (2007) Unlinking chromosome catenanes in vivo by site-specific recombination. EMBO J. 26 4228-38 PubMed
