1a41

Structural highlights

Function

[TOP1_VACCW] 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 the specific target site 5'-[CT]CCTTp site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(3'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 5'-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 5'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone.^{[1] [2]}

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

1. ↑ Nagarajan R, Stivers JT. Major groove interactions of vaccinia Topo I provide specificity by optimally positioning the covalent phosphotyrosine linkage. Biochemistry. 2006 May 9;45(18):5775-82. PMID:16669621 doi:http://dx.doi.org/10.1021/bi060133i
2. ↑ Stahley MR, Stivers JT. Mechanism and specificity of DNA strand exchange catalyzed by vaccinia DNA topoisomerase type I. Biochemistry. 2010 Apr 6;49(13):2786-95. PMID:20187656 doi:10.1021/bi902204v
3. ↑ Cheng C, Kussie P, Pavletich N, Shuman S. Conservation of structure and mechanism between eukaryotic topoisomerase I and site-specific recombinases. Cell. 1998 Mar 20;92(6):841-50. PMID:9529259