8-Oxoguanine rearranges the active site of human topoisomerase I

Lesher, D.; Pommier, ﻿Yves; Stewart, Lance; Redinbo, Matthew R.

doi:10.1073/pnas.192282699

Cited by 69 publications

(49 citation statements)

References 31 publications

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“…Measurement of single-turnover cleavage by the human enzyme showed that oxoG modification had less than a 2-fold effect on the forward transesterification rate; the religation rate to a 5Ј-OH oxoG acceptor stand was described as comparable with an unmodified control strand (40). A recent crystal structure of human topoisomerase I bound to a DNA containing an oxoG:C base pair 3Ј of the scissile phosphate highlighted an inactive conformation of the enzyme in which the tyrosine nucleophile (mutated to Phe) was oriented away from the scissile phosphate (51). This is reminiscent of the out-of-position state of the tyrosine in the structure of the free vaccinia topoisomerase (16).…”

Section: Discussionmentioning

confidence: 99%

Site-specific DNA Transesterification by Vaccinia Topoisomerase

Yakovleva

Tian

Sayer

et al. 2003

Journal of Biological Chemistry

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Vaccinia DNA topoisomerase forms a covalent DNA-(3-phosphotyrosyl)-enzyme intermediate at a specific target site 5-C ؉5 C ؉4 C ؉3 T ؉2 T ؉1 p2N ؊1 in duplex DNA. Here we study the effects of base modifications on the rate and extent of single-turnover DNA transesterification. Chiral trans opened C-10 R and S adducts of benzo[a]pyrene (BP) 7,8-diol 9,10-epoxide were introduced at single N 6 -deoxyadenosine (dA) positions within the 3-sequence of the nonscissile DNA strand. The R and S BPdA adducts intercalate from the major groove on the 5 and 3 sides of the modified base, respectively, and perturb local base stacking. We found that R and S BPdA modifications at ؉1A reduced the transesterification rate by a factor of 700 -1000 without affecting the yield of the covalent topoisomerase-DNA complex. BPdA modifications at ؉2A reduced the extent of transesterification and elicited rate decrements of 200-and 7000-fold for the S and R diastereomers, respectively. In contrast, BPdA adducts at the ؊2 position had no effect on the extent of the reaction and relatively little impact on the rate of cleavage. A more subtle probe of major groove contacts entailed substituting each of the purines of the nonscissile strand with its 8-oxo analog. The ؉3 oxoG modification slowed transesterification 35-fold, whereas other 8-oxo modifications were benign. 8-Oxo substitutions at the ؊1 position in the scissile strand slowed single-turnover cleavage by a factor of six but had an even greater slowing effect on religation, which resulted in an increase in the cleavage equilibrium constant. 2-Aminopurine at positions ؉3, ؉4, or ؉5 in the nonscissile strand had no effect on transesterification per se but had synergistic effects when combined with 8-oxoA at position ؊1 in the scissile strand. These findings illuminate the functional interface of vaccinia topoisomerase with the DNA major groove.Poxvirus DNA topoisomerase is an attractive target for drug therapy of smallpox in light of its unique DNA recognition specificity, compact structure, and distinctive pharmacological sensitivities compared with human topoisomerase I (1-6). Poxvirus topoisomerase, exemplified by the 314-amino acid vaccinia virus enzyme, is a prototype of the type IB DNA topoisomerase family (7-9). Type IB enzymes cleave and rejoin one strand of the DNA duplex through a transient DNA-(3Ј-phosphotyrosyl)-enzyme intermediate.Poxvirus topoisomerases bind and cleave duplex DNA at a pentapyrimidine target sequence, 5Ј-(T/C)CCTTp2 (3). The T2 nucleotide (defined as the ϩ1 nucleotide) is linked to Tyr-274 of the vaccinia enzyme. Four conserved amino acid side chains found in all type IB topoisomerases (Arg-130, Lys-167, Arg-223, and His-265 in the vaccinia enzyme) are responsible for catalyzing the attack by tyrosine on the scissile phosphodiester to form the covalent intermediate (10 -12). The topoisomerase binds to DNA as a C-shaped protein clamp formed by an 80-amino acid N-terminal domain that contacts the DNA major groove and a 234-amino acid C-terminal catalytic domain ...

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Section: Discussionmentioning

confidence: 99%

Site-specific DNA Transesterification by Vaccinia Topoisomerase

Yakovleva

Tian

Sayer

et al. 2003

Journal of Biological Chemistry

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“…3B -curved arrow). Crystal structures of Top1 [20][21][22] show the enzyme encircling the DNA tightly like a clamp (Fig. 3D), which accounts for the fact that Top1 controls the processive relaxation of supercoiled DNA [20,[23][24][25] Two key pharmacological properties of camptothecins need to be stressed.…”

Section: A Introduction: Mammalian Topoisomerase Families Top1 Funcmentioning

confidence: 99%

Repair of Topoisomerase I‐Mediated DNA Damage

Pommier

Barceló

Rao

et al. 2006

Progress in Nucleic Acid Research and Molecular Biology

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Topoisomerase I (Top1) is an abundant and essential enzyme. Top1 is the selective target of camptothecins, which are effective anticancer agents. Top1-DNA cleavage complexes can also be trapped by various endogenous and exogenous DNA lesions including mismatches, abasic sites and carcinogenic adducts. Tyrosyl-DNA phosphodiesterase (Tdp1) is one of the repair enzymes for Top1-DNA covalent complexes. Tdp1 forms a multiprotein complex that includes poly(ADP) ribose polymerase (PARP). PARP-deficient cells are hypersensitive to camptothecins and functionally deficient for Tdp1. We will review recent developments in several pathways involved in the repair of Top1 cleavage complexes and the role of Chk1 and Chk2 checkpoint kinases in the cellular responses to Top1 inhibitors. The genes conferring camptothecin hypersensitivity are compiled for humans, budding yeast and fission yeast. A. Introduction: Mammalian Topoisomerase Families, Top1 Functions and Catalytic MechanismsSeven topoisomerase genes are encoded in the human nuclear genome [1]. The enzymes (abbreviated Topo or Top) have been numbered in the order of their discovery except for the most recent enzyme, mitochondrial topoisomerase I (Top1mt) [2,3]. Vertebrate cells contain two Top1 (Top1 for the nuclear genome and Top1mt for the mitochondrial genome), two Top2 (Top2α and β) and two Top3 (Top3α and β). The seventh topoisomerase is Spo11, whose expression is restricted to germ cells. Top3α forms heterodimers with BLM (the gene product deficient in Bloom syndrome) and is functionally related to the resolution of post-replicative hemicatenanes and recombination intermediates [4,5]. Top1 proteins belong to the family of the tyrosine recombinases (which includes λ-integrase, Flip and Cre recombinases), and Top2 is related to bacterial gyrase and Topo IV, which are the targets of quinolone antibiotics.Topoisomerases and tyrosine recombinases nick and religate DNA by forming a covalent enzyme-DNA intermediate between an enzyme catalytic tyrosine residue and the end of the broken DNA (Fig. 1). These covalent intermediates are generally referred to as "cleavage (or cleavable) complexes" (Fig. 2). Topoisomerases have also been classified in two groups depending whether they cleave and religate one strand (type I) or both strands (type II) of the DNA duplex. Type I enzymes include Top1 (nuclear), Top1mt, Top3α and β and type II enzymes include Top2α and β and Spo11.Top1 is essential in vertebrates and flies but not in yeast. Knocking out the TOP1 gene results in early embryonic lethality in mouse [6] and fly [7]. By contrast, yeast survives in the absence *To whom reprint requests should be addressed, Bldg. 37, Rm. 5068, NIH, Bethesda, MD 20892-4255 [8]. Top1 is expressed constitutively throughout the cell cycle [9] and is concentrated in the nucleolus [10,11]. Its main function is to relieve both positive and negative DNA supercoiling generated by transcription and replication, and possibly DNA repair and chromatin remodeling [1,[12][13][14]. The mechanistic sim...

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“…nicks, mismatches, abasic sites, and AraC-substituted DNA), are now known to trap TOP1-DNA cleavage complexes (20 -23). It has been recently demonstrated that oxidative base lesions such as 8-oxoG can increase TOP1 binding to DNA and also induce a 3-7-fold increase in TOP1 cleavage complexes (24,25).…”

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confidence: 99%

Hydrogen Peroxide Induces Topoisomerase I-mediated DNA Damage and Cell Death

Daroui

Desai

Li³

et al. 2004

Journal of Biological Chemistry

123

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Reactive oxygen species modify DNA, generating various DNA lesions including modified bases such as 8-oxoguanine (8-oxoG). These base-modified DNA lesions have been shown to trap DNA topoisomerase I (TOP1) into covalent cleavage complexes. In this study, we have investigated the role of TOP1 in hydrogen peroxide toxicity. We showed that ectopic expression of TOP1 in Saccharomyces cerevisiae conferred sensitivity to hydrogen peroxide, and this sensitivity was dependent on RAD9 checkpoint function. Moreover, in the mammalian cell culture system, hydrogen peroxide-induced growth inhibition and apoptosis were shown to be partly TOP1-dependent as evidenced by a specific increase in resistance to hydrogen peroxide in TOP1-deficient P388/ CPT45 murine leukemia cells as compared with their TOP1-proficient parental cell line P388. In addition, hydrogen peroxide was shown to induce TOP1-DNA crosslinks. These results support a model in which hydrogen peroxide promotes the trapping of TOP1 on oxidative DNA lesions to form TOP1-DNA cleavage complexes that contribute to hydrogen peroxide toxicity.

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8-Oxoguanine rearranges the active site of human topoisomerase I

Cited by 69 publications

References 31 publications

Site-specific DNA Transesterification by Vaccinia Topoisomerase

Site-specific DNA Transesterification by Vaccinia Topoisomerase

Repair of Topoisomerase I‐Mediated DNA Damage

Hydrogen Peroxide Induces Topoisomerase I-mediated DNA Damage and Cell Death

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