Structural highlights
Function
[TOP3A_HUMAN] Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(5'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 3'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 3'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone. Essential component of the RMI complex, a complex that plays an important role in the processing of homologous recombination intermediates to limit DNA crossover formation in cells. Has DNA decatenation activity.[1] [2]
See Also
References
- ↑ Hanai R, Caron PR, Wang JC. Human TOP3: a single-copy gene encoding DNA topoisomerase III. Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3653-7. PMID:8622991
- ↑ Yang J, Bachrati CZ, Ou J, Hickson ID, Brown GW. Human topoisomerase IIIalpha is a single-stranded DNA decatenase that is stimulated by BLM and RMI1. J Biol Chem. 2010 Jul 9;285(28):21426-36. doi: 10.1074/jbc.M110.123216. Epub 2010, May 5. PMID:20445207 doi:http://dx.doi.org/10.1074/jbc.M110.123216
