Bioinformatic Analysis of Topoisomerase IIα Reveals Interdomain Interdependencies and Critical C-Terminal Domain Residues.

DNA Topoisomerase IIα (Top2A) is a nuclear enzyme that is a cancer drug target, and there is interest in identifying novel sites on the enzyme to inhibit cancer cells more selectively and to reduce off-target toxicity. The C-terminal domain (CTD) is one potential target, but it is an intrinsically disordered domain, which prevents structural analysis. Therefore, we set out to analyze the sequence of Top2A from 105 species using bioinformatic analysis, including the PSICalc algorithm, Shannon entropy analysis, and other approaches.

Faith and facts: Exploring the intersection of religion and science among anatomy educators.

The intersection of religion and science often elicits polarizing views among scientists, though approximately half of American scientists identify as religious. Mounting evidence also supports the role of spirituality in comprehensive patient care. The purpose of this study was to explore the religiosity of faculty who teach in the anatomical sciences at U.

No Time to Relax and Unwind: Exploration of Topoisomerases and a Growing Field of Study.

With the topoisomerase field in its sixth decade [...

Inhibition of Topoisomerases by Metal Thiosemicarbazone Complexes.

Topoisomerases, common targets for anti-cancer therapeutics, are crucial enzymes for DNA replication, transcription, and many other aspects of DNA metabolism. The potential anti-cancer effects of thiosemicarbazones (TSC) and metal-TSC complexes have been demonstrated to target several biological processes, including DNA metabolism. Human topoisomerases were discovered among the molecular targets for TSCs, and metal-chelated TSCs specifically displayed significant inhibition of topoisomerase II.

PSICalc: a novel approach to identifying and ranking critical non-proximal interdependencies within the overall protein structure.

Motivation: AlphaFold has been a major advance in predicting protein structure, but still leaves the problem of determining which sub-molecular components of a protein are essential for it to carry out its function within the cell. Direct coupling analysis predicts two- and three-amino acid contacts, but there may be essential interdependencies that are not proximal within the 3D structure. The problem to be addressed is to design a computational method that locates and ranks essential non-proximal interdependencies within a protein involving five or more amino acids, using large, multiple sequence alignments (MSAs) for both globular and intrinsically unstructured proteins.

Exploration of the Role of the C-Terminal Domain of Human DNA Topoisomerase IIα in Catalytic Activity.

Human topoisomerase IIα (TOP2A) is a vital nuclear enzyme involved in resolving knots and tangles in DNA during replication and cell division. TOP2A is a homodimer with a symmetrical, multidomain structure. While the N-terminal and core regions of the protein are well-studied, the C-terminal domain is poorly understood but is involved in enzyme regulation and is predicted to be intrinsically disordered.

Cannabidiol oxidation product HU-331 is a potential anticancer cannabinoid-quinone: a narrative review.

Cannabidiol and related cannabinoids are under exploration for the treatment of a number of disease states. The cannabinoid-quinone HU-331 has been studied as a potential anticancer therapeutic. Previous studies provide evidence that HU-331 displays anticancer activity without some of the known adverse events associated with traditional anticancer agents.

Synthesis and evaluation of etoposide and podophyllotoxin analogs against topoisomerase IIα and HCT-116 cells.

Etoposide is a widely-used anticancer agent that targets human type II topoisomerases. Evidence suggests that metabolism of etoposide in myeloid progenitor cells is associated with translocations involved in leukemia development. Previous studies suggest halogenation at the C-2' position of etoposide reduces metabolism.

Clarifying the Mechanism of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα and IIβ.

Topoisomerase II is a nuclear enzyme involved in the maintenance of DNA and is an effective anticancer drug target. However, several clinical topoisomerase II-targeted agents display significant off-target toxicities and adverse events. Thus, it is important to continue characterizing compounds with activity against topoisomerase II.

Examining the Impact of Antimicrobial Fluoroquinolones on Human DNA Topoisomerase IIα and IIβ.

Fluoroquinolones are a class of widely prescribed antibiotics with a broad range of activity against Gram-positive, Gram-negative, and some atypical microbes. Unfortunately, these drugs are associated with significant adverse events including neuropathy, tendinopathy, cardiac rhythm abnormalities, and mental health side effects. The mechanism by which fluoroquinolones cause many of these toxicities is unknown.

Structural and Metal Ion Effects on Human Topoisomerase IIα Inhibition by α-(N)-Heterocyclic Thiosemicarbazones.

Our previous research has shown that α-(N)-heterocyclic thiosemicarbazone (TSC) metal complexes inhibit human topoisomerase IIα (TopoIIα), while the ligands without metals do not. To find out the structural elements of TSC that are important for inhibiting TopoIIα, we have synthesized two series of α-(N)-heterocyclic TSCs with various substrate ring segments, side chain substitutions, and metal ions, and we have examined their activities in TopoIIα-mediated plasmid DNA relaxation and cleavage assays. Our goal is to explore the structure-activity relationship of α-(N)-heterocyclic TSCs and their effect on TopoIIα.

HU-331 and Oxidized Cannabidiol Act as Inhibitors of Human Topoisomerase IIα and β.

Topoisomerase II is a critical enzyme in replication, transcription, and the regulation of chromatin topology. Several anticancer agents target topoisomerases in order to disrupt cell growth. Cannabidiol is a major non-euphoriant, pharmacologically active component of cannabis.

Two-Mechanism Model for the Interaction of Etoposide Quinone with Topoisomerase IIα.

Topoisomerase II is an essential nuclear enzyme involved in regulating DNA topology to facilitate replication and cell division. Disruption of topoisomerase II function by chemotherapeutic agents is in use as an effective strategy to fight cancer. Etoposide is an anticancer therapeutic that disrupts the catalytic cycle of topoisomerase II and stabilizes enzyme-bound DNA strand breaks.

Examination of the Impact of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα.

Type II DNA topoisomerases resolve topological knots and tangles in DNA that result from routine cellular processes and are effective targets for anticancer therapeutics. To this end, thiosemicarbazones have been identified as having the ability to kill cancer cells from several cell lines. Literature evidence suggests that at least some thiosemicarbazones have an impact on topoisomerase II activity.

HU-331 is a catalytic inhibitor of topoisomerase IIα.

Topoisomerases are essential enzymes that are involved in DNA metabolism. Topoisomerase II generates transient DNA strand breaks that are stabilized by anticancer drugs, such as doxorubicin, causing an accumulation of DNA damage. However, doxorubicin causes cardiac toxicity and, like etoposide and other topoisomerase II-targeted agents, can induce DNA damage, resulting in secondary cancers.

Catalytic core of human topoisomerase IIα: insights into enzyme-DNA interactions and drug mechanism.

Coordination between the N-terminal gate and the catalytic core of topoisomerase II allows the proper capture, cleavage, and transport of DNA during the catalytic cycle. Because the activities of these domains are tightly linked, it has been difficult to discern their individual contributions to enzyme-DNA interactions and drug mechanism. To further address the roles of these domains, we analyzed the activity of the catalytic core of human topoisomerase IIα.

Etoposide quinone is a covalent poison of human topoisomerase IIβ.

Etoposide is a topoisomerase II poison that is utilized to treat a broad spectrum of human cancers. Despite its wide clinical use, 2-3% of patients treated with etoposide eventually develop treatment-related acute myeloid leukemias (t-AMLs) characterized by rearrangements of the MLL gene. The molecular basis underlying the development of these t-AMLs is not well understood; however, previous studies have implicated etoposide metabolites (i.

Etoposide catechol is an oxidizable topoisomerase II poison.

Topoisomerase II regulates DNA topology by generating transient double-stranded breaks. The anticancer drug etoposide targets topoisomerase II and is associated with the formation of secondary leukemias in patients. The quinone and catechol metabolites of etoposide may contribute to strand breaks that trigger leukemic translocations.

Etoposide quinone is a redox-dependent topoisomerase II poison.

Etoposide is a topoisomerase II poison that is used to treat a variety of human cancers. Unfortunately, 2-3% of patients treated with etoposide develop treatment-related leukemias characterized by 11q23 chromosomal rearrangements. The molecular basis for etoposide-induced leukemogenesis is not understood but is associated with enzyme-mediated DNA cleavage.

The use of divalent metal ions by type II topoisomerases.

Type II topoisomerases are essential enzymes that regulate DNA under- and overwinding and remove knots and tangles from the genetic material. In order to carry out their critical physiological functions, these enzymes utilize a double-stranded DNA passage mechanism that requires them to generate a transient double-stranded break. Consequently, while necessary for cell survival, type II topoisomerases also have the capacity to fragment the genome.

A novel and unified two-metal mechanism for DNA cleavage by type II and IA topoisomerases.

Type II topoisomerases are required for the management of DNA tangles and supercoils, and are targets of clinical antibiotics and anti-cancer agents. These enzymes catalyse the ATP-dependent passage of one DNA duplex (the transport or T-segment) through a transient, double-stranded break in another (the gate or G-segment), navigating DNA through the protein using a set of dissociable internal interfaces, or 'gates'. For more than 20 years, it has been established that a pair of dimer-related tyrosines, together with divalent cations, catalyse G-segment cleavage.

Metal ion interactions in the DNA cleavage/ligation active site of human topoisomerase IIalpha.

Human topoisomerase IIalpha utilizes a two-metal-ion mechanism for DNA cleavage. One of the metal ions (M(1)(2+)) is believed to make a critical interaction with the 3'-bridging atom of the scissile phosphate, while the other (M(2)(2+)) is believed to interact with a nonbridging oxygen of the scissile phosphate. Based on structural and mutagenesis studies of prokaryotic nucleic acid enzymes, it has been proposed that the active site divalent metal ions interact with type II topoisomerases through a series of conserved acidic amino acid residues.

DNA Topology and Topoisomerases: Teaching a "Knotty" Subject.

DNA is essentially an extremely long double-stranded rope in which the two strands are wound about one another. As a result, topological properties of the genetic material, including DNA underwinding and overwinding, knotting, and tangling, profoundly influence virtually every major nucleic acid process. Despite the importance of DNA topology, it is a conceptionally difficult subject to teach, because it requires students to visualize three-dimensional relationships.

Use of divalent metal ions in the dna cleavage reaction of human type II topoisomerases.

All type II topoisomerases require divalent metal ions to cleave and ligate DNA. To further elucidate the mechanistic basis for these critical enzyme-mediated events, the role of the metal ion in the DNA cleavage reaction of human topoisomerase IIbeta was characterized and compared to that of topoisomerase IIalpha. This study utilized divalent metal ions with varying thiophilicities in conjunction with DNA cleavage substrates that substituted a sulfur atom for the 3'-bridging oxygen or the nonbridging oxygens of the scissile phosphate.