4g0v

Human topoisomerase iibeta in complex with DNA and mitoxantrone

spinqualitylabelsall models 4g0v, resolution 2.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4g0v is a 6 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.548Å Ligands: MG, MIX Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TOP2B_HUMAN Control of topological states of DNA by transient breakage and subsequent rejoining of DNA strands. Topoisomerase II makes double-strand breaks. Indirectly involved in vitamin D-coupled transcription regulation via its association with the WINAC complex, a chromatin-remodeling complex recruited by vitamin D receptor (VDR), which is required for the ligand-bound VDR-mediated transrepression of the CYP27B1 gene. Publication Abstract from PubMed Type II topoisomerases (Top2s) alter DNA topology via the formation of an enzyme-DNA adduct termed cleavage complex, which harbors a transient double-strand break in one DNA to allow the passage of another. Agents targeting human Top2s are clinically active anticancer drugs whose trapping of Top2-mediated DNA breakage effectively induces genome fragmentation and cell death. To understand the structural basis of this drug action, we previously determined the structure of human Top2 beta-isoform forming a cleavage complex with the drug etoposide and DNA, and described the insertion of drug into DNA cleavage site and drug-induced decoupling of catalytic groups. By developing a post-crystallization drug replacement procedure that simplifies structural characterization of drug-stabilized cleavage complexes, we have extended the analysis toward other structurally distinct drugs, m-AMSA and mitoxantrone. Besides the expected drug intercalation, a switch in ribose puckering in the 3'-nucleotide of the cleavage site was robustly observed in the new structures, representing a new mechanism for trapping the Top2 cleavage complex. Analysis of drug-binding modes and the conformational landscapes of the drug-binding pockets provide rationalization of the drugs' structural-activity relationships and explain why Top2 mutants exhibit differential effects toward each drug. Drug design guidelines were proposed to facilitate the development of isoform-specific Top2-targeting anticancer agents. On the structural basis and design guidelines for type II topoisomerase-targeting anticancer drugs.,Wu CC, Li YC, Wang YR, Li TK, Chan NL Nucleic Acids Res. 2013 Sep 14. PMID:24038465 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Topoisomerase 3D structures

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