1a31

HUMAN RECONSTITUTED DNA TOPOISOMERASE I IN COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX

spinqualitylabelsall models 1a31, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1a31 is a 3 chain structure with sequence from Homo sapiens. The January 2006 RCSB PDB Molecule of the Month feature on Topoisomerases by David S. Goodsell is 10.2210/rcsb_pdb/mom_2006_1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: 5IU, PTR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Topoisomerase 3D structures

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