| Structural highlights
1a35 is a 3 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | NonStd Res: | |
| Activity: | DNA topoisomerase, with EC number 5.99.1.2 |
| Resources: | FirstGlance, OCA, RCSB, PDBsum |
Disease
[TOP1_HUMAN] Note=A chromosomal aberration involving TOP1 is found in a form of therapy-related myelodysplastic syndrome. Translocation t(11;20)(p15;q11) with NUP98.
Function
[TOP1_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-(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 (By similarity). Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells.[1] [2] [3] [4]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Topoisomerases I promote the relaxation of DNA superhelical tension by introducing a transient single-stranded break in duplex DNA and are vital for the processes of replication, transcription, and recombination. The crystal structures at 2.1 and 2.5 angstrom resolution of reconstituted human topoisomerase I comprising the core and carboxyl-terminal domains in covalent and noncovalent complexes with 22-base pair DNA duplexes reveal an enzyme that "clamps" around essentially B-form DNA. The core domain and the first eight residues of the carboxyl-terminal domain of the enzyme, including the active-site nucleophile tyrosine-723, share significant structural similarity with the bacteriophage family of DNA integrases. A binding mode for the anticancer drug camptothecin is proposed on the basis of chemical and biochemical information combined with these three-dimensional structures of topoisomerase I-DNA complexes.
Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA.,Redinbo MR, Stewart L, Kuhn P, Champoux JJ, Hol WG Science. 1998 Mar 6;279(5356):1504-13. PMID:9488644[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ D'Arpa P, Machlin PS, Ratrie H 3rd, Rothfield NF, Cleveland DW, Earnshaw WC. cDNA cloning of human DNA topoisomerase I: catalytic activity of a 67.7-kDa carboxyl-terminal fragment. Proc Natl Acad Sci U S A. 1988 Apr;85(8):2543-7. PMID:2833744
- ↑ Eisenreich A, Bogdanov VY, Zakrzewicz A, Pries A, Antoniak S, Poller W, Schultheiss HP, Rauch U. Cdc2-like kinases and DNA topoisomerase I regulate alternative splicing of tissue factor in human endothelial cells. Circ Res. 2009 Mar 13;104(5):589-99. doi: 10.1161/CIRCRESAHA.108.183905. Epub, 2009 Jan 22. PMID:19168442 doi:10.1161/CIRCRESAHA.108.183905
- ↑ Interthal H, Quigley PM, Hol WG, Champoux JJ. The role of lysine 532 in the catalytic mechanism of human topoisomerase I. J Biol Chem. 2004 Jan 23;279(4):2984-92. Epub 2003 Oct 31. PMID:14594810 doi:10.1074/jbc.M309959200
- ↑ Ioanoviciu A, Antony S, Pommier Y, Staker BL, Stewart L, Cushman M. Synthesis and mechanism of action studies of a series of norindenoisoquinoline topoisomerase I poisons reveal an inhibitor with a flipped orientation in the ternary DNA-enzyme-inhibitor complex as determined by X-ray crystallographic analysis. J Med Chem. 2005 Jul 28;48(15):4803-14. PMID:16033260 doi:10.1021/jm050076b
- ↑ Redinbo MR, Stewart L, Kuhn P, Champoux JJ, Hol WG. Crystal structures of human topoisomerase I in covalent and noncovalent complexes with DNA. Science. 1998 Mar 6;279(5356):1504-13. PMID:9488644
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