|4g0v, resolution 2.55Å ()|
|Related:||3qx3, 4g0u, 4g0w, 4j3n|
Human topoisomerase iibeta in complex with DNA and mitoxantrone
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.
[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. 
About this Structure
- Wu CC, Li YC, Wang YR, Li TK, Chan NL. On the structural basis and design guidelines for type II topoisomerase-targeting anticancer drugs. Nucleic Acids Res. 2013 Sep 14. PMID:24038465 doi:10.1093/nar/gkt828
- ↑ West KL, Meczes EL, Thorn R, Turnbull RM, Marshall R, Austin CA. Mutagenesis of E477 or K505 in the B' domain of human topoisomerase II beta increases the requirement for magnesium ions during strand passage. Biochemistry. 2000 Feb 15;39(6):1223-33. PMID:10684600
- ↑ Kitagawa H, Fujiki R, Yoshimura K, Mezaki Y, Uematsu Y, Matsui D, Ogawa S, Unno K, Okubo M, Tokita A, Nakagawa T, Ito T, Ishimi Y, Nagasawa H, Matsumoto T, Yanagisawa J, Kato S. The chromatin-remodeling complex WINAC targets a nuclear receptor to promoters and is impaired in Williams syndrome. Cell. 2003 Jun 27;113(7):905-17. PMID:12837248