Structural highlights
Function
TOP3_ECOLI 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 than 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. TOP3 is a potent decatenase.[1] [2]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
See Also
References
- ↑ DiGate RJ, Marians KJ. Molecular cloning and DNA sequence analysis of Escherichia coli topB, the gene encoding topoisomerase III. J Biol Chem. 1989 Oct 25;264(30):17924-30. PMID:2553698
- ↑ Srivenugopal KS, Lockshon D, Morris DR. Escherichia coli DNA topoisomerase III: purification and characterization of a new type I enzyme. Biochemistry. 1984 Apr 24;23(9):1899-906. PMID:6326814
