Topoisomerase IV
Contents
About
Topoisomerase IV is the main decatenase for the E.coli chromosome. It is a heterotetramer consisting of 2 subunits of ParC and 2 components of ParE.
Function
Although its major role is as the main cellular decatenase, Topo IV also acts to relax positive supercoils, remove precatenanes formed during DNA replication, and untangle DNA knots.
Mechanism
Type II Topoisomerase Catalytic Mechanism. This figure is taken from Schoeffler 2005[1]
- Binding the Gate (G) segment
- Binding/Hydrolysis of ATP
- Trapping the Transfer (T) segment
- Transient cleavage of the G segment
- Passage of the T segment through the break
- Resealing the Break of the G segment
- For more details, also look at Corbett et al. (2005)[2].
Regulation
- FtsK has been shown to stimulate Topo IV-catalyzed relaxation of (+) scDNA and inhibits relaxation of (-) scDNA[3].
- SeqA stimulates Topo IV's relaxing and decatenating activities[4].
- MreB modulates Topo IV's decatenation activity dependent on MreB's polymerization state[5]
Activity Assays
Notes
rescue of parE(ts) by DnaX overexpression is dependent on XerCD-dif-FtsK recombination. Cre-loxP site-specific recombination can also substitute[7].
Related GO Terms
- DNA Topoisomerase activity
- DNA Topoisomerase (ATP-hydrolyzing) activity
- Chromosome Segregation
- Plasmid Partitioning
- Sister Chromatid Cohesion
- DNA Binding
- DNA Topological Change
- ATP Binding
References
- ↑ Schoeffler, AJ & Berger, JM (2005) Recent advances in understanding structure-function relationships in the type II topoisomerase mechanism. Biochem. Soc. Trans. 33 1465-70 PubMed
- ↑ Corbett, KD et al. (2005) The structural basis for substrate specificity in DNA topoisomerase IV. J. Mol. Biol. 351 545-61 PubMed
- ↑ 3.0 3.1 3.2 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
- ↑ Kang, S et al. (2003) SeqA protein stimulates the relaxing and decatenating activities of topoisomerase IV. J. Biol. Chem. 278 48779-85 PubMed
- ↑ Madabhushi, R & Marians, KJ (2009) Actin homolog MreB affects chromosome segregation by regulating topoisomerase IV in Escherichia coli. Mol. Cell 33 171-80 PubMed
- ↑ Espeli, O et al. (2003) A physical and functional interaction between Escherichia coli FtsK and topoisomerase IV. J. Biol. Chem. 278 44639-44 PubMed
- ↑ Grainge, I et al. (2007) Unlinking chromosome catenanes in vivo by site-specific recombination. EMBO J. 26 4228-38 PubMed
