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Hájková-Strejcová A, Augustín M, Barek J, Iffelsberger C, Matysik FM, Vyskočil V. New strategy in electrochemical investigation of DNA damage demonstrated on genotoxic derivatives of fluorene. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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2
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Glover SA, Schumacher RR. Mutagenicity of N-acyloxy-N-alkoxyamides as an indicator of DNA intercalation: The role of fluorene and fluorenone substituents as DNA intercalators. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2021; 863-864:503299. [PMID: 33678240 DOI: 10.1016/j.mrgentox.2020.503299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 06/12/2023]
Abstract
N-Acyloxy-N-alkoxyamides are direct-acting mutagens in S. typhimurium TA100 and TA98. A reliable QSAR for their activity in TA100 has been developed, which indicates reversible intercalation into the DNA helix through naphthalene substituents. In this paper, we show that fluorene as a substituent does not facilitate intercalation while fluorenone does, although the efficacy is determined by the position of substitution on the fluorenone as well as the N-acyloxy-N-alkoxyamide side chain. Where intercalation is evident, the increased binding to DNA is similar to that of naphthalene and is worth the equivalent of ca four LogP hydrophobicity units. 4-Substituted fluorenones, where the anomeric amide group is in the bay region do not intercalate, which is attributed to the requirement for a weaker edge-on, rather than an end-on intercalation. Mutagencity in S. typhimurium TA98, which detects frame shifts through intercalation, supports the findings. Fluorene appears not to intercalate, which points to the fact that the charge delocalised 2-fluorenylnitrenium ion, the ultimate metabolite from 2-aminofluorene (AF) and 2-acetylaminofluorene (AAF) is the itercalating agent responsible for frameshift mutations leading to their carcinogenicity.
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Affiliation(s)
- Stephen A Glover
- Chemistry Department, School of Science and Technology, University of New England, Armidale, New South Wales 2351, Australia.
| | - Rhiannon R Schumacher
- Chemistry Department, School of Science and Technology, University of New England, Armidale, New South Wales 2351, Australia
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3
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Berger FD, Manderville RA, Sturla SJ. Adduct Fluorescence as a Tool to Decipher Sequence Impact on Frameshift Mutations Mediated by a C-Linked C8-Biphenyl-Guanine Lesion. Chem Res Toxicol 2019; 32:784-791. [PMID: 30785283 DOI: 10.1021/acs.chemrestox.9b00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aromatic chemicals can undergo metabolic activation to afford electrophilic species that react at the C8-site of 2'-deoxyguanosine (dG) to generate bulky C8-dG adducts as a basis of initiating carcinogenesis. These DNA lesions have served as models to understand the mechanism of frameshift mutagenesis, especially within CG-dinucleotide repeat sequences, such as NarI (5'-GGCXCC-3', where X = C8-dG adduct), however there is still limited capacity to predict the likelihood of mutation arising within particular contexts, and hence chemistry-based strategies are needed for probing relationships between nucleic acid sequence and structure with replication errors. In the NarI sequence, certain C8-dG adducts may trigger in the course of DNA synthesis the formation of a slipped mutagenic intermediate (SMI) that contains a two nucleotide (XC) bulge in the template strand that can form upstream of the polymerase active site. This distortion facilitates polymerization but affords a GC dinucleotide deletion product (-2 frameshift mutation). In the current study, incorporating the fluorescent C-linked 4-fluorobiphenyl-dG (FBP-dG) adduct into two 22-mer templates containing CG-dinucleotide repeats ( NarI: 3'-CXCGGC-5' and CG3: 3'-CXCGCG-5', X = FBP-dG) and performing primer extension reactions using DNA polymerase I, Klenow fragment exo- (Kf-) revealed a dramatic sequence-based difference in polymerase bypass efficiency. Primer extension past FBP-dG within the NarI sequence was strongly blocked, whereas Kf- extended the primer past FBP-dG within a CG3 template to afford a full-length product and the GC dinucleotide deletion. To model the nucleotide insertion steps in the fully paired (FP) versus the slipped mutagenic (SM) translesion pathways, adducted template:primer duplexes were constructed and characterized by UV thermal denaturation and fluorescence spectroscopy. The emission intensity of the FBP-dG lesion exhibits sensitivity to SMI formation (turn-on) versus a FP duplex (turn-off), permitting insight into adduct base-pairing within the template:primer duplexes. This fluorescence sensitivity provides a rationale for sequence impact on -2 frameshift mutations mediated by the C-linked FBP-dG lesion.
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Affiliation(s)
- Florence D Berger
- Department of Health Sciences and Technology , ETH Zurich , 8092 Zurich , Switzerland
| | - Richard A Manderville
- Departments of Chemistry and Toxicology , University of Guelph , Guelph , Ontario , Canada N1G 2W1
| | - Shana J Sturla
- Department of Health Sciences and Technology , ETH Zurich , 8092 Zurich , Switzerland
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4
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Thangavel N, Ganesan VV, Nair BU. Conformation Specific Binding of [Ru(phen)2
(dppz)]2+
with Mono- and Cluster Arylamine-DNA Adducts. ChemistrySelect 2018. [DOI: 10.1002/slct.201802172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Nandhini Thangavel
- Inorganic and Physical Chemistry Laboratory; CSIR-Central Leather Research Institute, Adyar; Chennai 600 020 India
- Academy of Scientific and Innovative Research (AcSIR); CSIR-Central Leather Research Institute, Adyar; Chennai 600 020 India
| | - Vaidyanathan V. Ganesan
- Advanced Materials Laboratory; CSIR-Central Leather Research Institute, Adyar; Chennai 600 020 India
- Academy of Scientific and Innovative Research (AcSIR); CSIR-Central Leather Research Institute, Adyar; Chennai 600 020 India
| | - Balachandran U. Nair
- Inorganic and Physical Chemistry Laboratory; CSIR-Central Leather Research Institute, Adyar; Chennai 600 020 India
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5
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Xu L, Cho BP. Conformational Insights into the Mechanism of Acetylaminofluorene-dG-Induced Frameshift Mutations in the NarI Mutational Hotspot. Chem Res Toxicol 2016; 29:213-26. [PMID: 26733364 DOI: 10.1021/acs.chemrestox.5b00484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Frameshift mutagenesis encompasses the gain or loss of DNA base pairs, resulting in altered genetic outcomes. The NarI restriction site sequence 5'-G1G2CG3CX-3' in Escherichia coli is a well-known mutational hotspot, in which lesioning of acetylaminofluorene (AAF) at G3* induces a greater -2 deletion frequency than that at other guanine sites. Its mutational efficiency is modulated by the nature of the nucleotide in the X position (C ∼ A > G ≫ T). Here, we conducted a series of polymerase-free solution experiments that examine the conformational and thermodynamic basis underlying the propensity of adducted G3 to form a slipped mutagenic intermediate (SMI) and its sequence dependence during translesion synthesis (TLS). Instability of the AAF-dG3:dC pair at the replication fork promoted slippage to form a G*C bulge-out SMI structure, consisting of S- ("lesion stacked") and B-SMI ("lesion exposed") conformations, with conformational rigidity increasing as a function of primer elongation. We found greater stability of the S- compared to the B-SMI conformer throughout TLS. The dependence of their population ratios was determined by the 3'-next flanking base X at fully elongated bulge structures, with 59% B/41% S and 86% B/14% S for the dC and dT series, respectively. These results indicate the importance of direct interactions of the hydrophobic AAF lesion with the 3'-next flanking base pair and its stacking fit within the -2 bulge structure. A detailed conformational understanding of the SMI structures and their sequence dependence may provide a useful model for DNA polymerase complexes.
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Affiliation(s)
- Lifang Xu
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Bongsup P Cho
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
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6
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Local Geometry and Evolutionary Conservation of Protein Surfaces Reveal the Multiple Recognition Patches in Protein-Protein Interactions. PLoS Comput Biol 2015; 11:e1004580. [PMID: 26690684 PMCID: PMC4686965 DOI: 10.1371/journal.pcbi.1004580] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 10/04/2015] [Indexed: 11/19/2022] Open
Abstract
Protein-protein interactions (PPIs) are essential to all biological processes and they represent increasingly important therapeutic targets. Here, we present a new method for accurately predicting protein-protein interfaces, understanding their properties, origins and binding to multiple partners. Contrary to machine learning approaches, our method combines in a rational and very straightforward way three sequence- and structure-based descriptors of protein residues: evolutionary conservation, physico-chemical properties and local geometry. The implemented strategy yields very precise predictions for a wide range of protein-protein interfaces and discriminates them from small-molecule binding sites. Beyond its predictive power, the approach permits to dissect interaction surfaces and unravel their complexity. We show how the analysis of the predicted patches can foster new strategies for PPIs modulation and interaction surface redesign. The approach is implemented in JET2, an automated tool based on the Joint Evolutionary Trees (JET) method for sequence-based protein interface prediction. JET2 is freely available at www.lcqb.upmc.fr/JET2.
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7
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Brenlla A, Rueda D, Romano LJ. Mechanism of aromatic amine carcinogen bypass by the Y-family polymerase, Dpo4. Nucleic Acids Res 2015; 43:9918-27. [PMID: 26481355 PMCID: PMC4787768 DOI: 10.1093/nar/gkv1067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/05/2015] [Indexed: 01/16/2023] Open
Abstract
Bulky DNA damage inhibits DNA synthesis by replicative polymerases and often requires the action of error prone bypass polymerases. The exact mechanism governing adduct-induced mutagenesis and its dependence on the DNA sequence context remains unclear. In this work, we characterize Dpo4 binding conformations and activity with DNA templates modified with the carcinogenic DNA adducts, 2-aminofluoene (AF) or N-acetyl-2-aminofluorene (AAF), using single-molecule FRET (smFRET) analysis and DNA synthesis extension assays. We find that in the absence of dNTPs, both adducts alter polymerase binding as measured by smFRET, but the addition of dNTPs induces the formation of a ternary complex having what appears to be a conformation similar to the one observed with an unmodified DNA template. We also observe that the misincorporation pathways for each adduct present significant differences: while an AF adduct induces a structure consistent with the previously observed primer-template looped structure, its acetylated counterpart uses a different mechanism, one consistent with a dNTP-stabilized misalignment mechanism.
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Affiliation(s)
- Alfonso Brenlla
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | - David Rueda
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA Department of Medicine, Section of Virology, Imperial College London, London, UK Single Molecule Imaging Group, MRC Clinical Sciences Centre, Imperial College London, London, UK
| | - Louis J Romano
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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8
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Abstract
I spent my childhood and adolescence in North and South Carolina, attended Duke University, and then entered Duke Medical School. One year in the laboratory of George Schwert in the biochemistry department kindled my interest in biochemistry. After one year of residency on the medical service of Duke Hospital, chaired by Eugene Stead, I joined the group of Arthur Kornberg at Stanford Medical School as a postdoctoral fellow. Two years later I accepted a faculty position at Harvard Medical School, where I remain today. During these 50 years, together with an outstanding group of students, postdoctoral fellows, and collaborators, I have pursued studies on DNA replication. I have experienced the excitement of discovering a number of important enzymes in DNA replication that, in turn, triggered an interest in the dynamics of a replisome. My associations with industry have been stimulating and fostered new friendships. I could not have chosen a better career.
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Affiliation(s)
- Charles C Richardson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115;
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9
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Xu L, Vaidyanathan VG, Cho BP. Real-time surface plasmon resonance study of biomolecular interactions between polymerase and bulky mutagenic DNA lesions. Chem Res Toxicol 2014; 27:1796-807. [PMID: 25195494 PMCID: PMC4203393 DOI: 10.1021/tx500252z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Surface plasmon resonance (SPR) was
used to measure polymerase-binding
interactions of the bulky mutagenic DNA lesions N-(2′-deoxyguanosin-8-yl)-4′-fluoro-4-aminobiphenyl
(FABP) or N-(2′-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene
(FAAF) in the context of two unique 5′-flanking bases (CG*A and TG*A). The enzymes used
were exo-nuclease-deficient Klenow fragment (Kf-exo–) or polymerase β (pol β). Specific binary and ternary
DNA binding affinities of the enzymes were characterized at subnanomolar
concentrations. The SPR results showed that Kf-exo– binds strongly to a double strand/single strand template/primer
junction, whereas pol β binds preferentially to double-stranded
DNA having a one-nucleotide gap. Both enzymes exhibited tight binding
to native DNA, with high nucleotide selectivity, where the KD values for each base pair increased in the
order dCTP ≪ dTTP ∼ dATP ≪ dGTP. In contrast
to that for pol β, Kf-exo– binds tightly to
lesion-modified templates; however, both polymerases exhibited minimal
nucleotide selectivity toward adducted DNA. Primer steady-state kinetics
and 19F NMR results support the SPR data. The relative
insertion efficiency fins of dCTP opposite
FABP was significantly higher in the TG*A sequence
compared to that in CG*A. Although Kf-exo– was not sensitive to the presence of a DNA lesion,
FAAF-induced conformational heterogeneity perturbed the active site
of pol β, weakening the enzyme’s ability to bind to FAAF
adducts compared to FABP adducts. The present study demonstrates the
effectiveness of SPR for elucidating how lesion-induced conformational
heterogeneity affects the binding capability of polymerases and ultimately
the nucleotide insertion efficiency.
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Affiliation(s)
- Lifang Xu
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island , Kingston, Rhode Island 02881, United States
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10
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Serio N, Prignano L, Peters S, Levine M. Detection of Medium-Sized Polycyclic Aromatic Hydrocarbons via Fluorescence Energy Transfer. Polycycl Aromat Compd 2014; 34:561-572. [PMID: 25821390 DOI: 10.1080/10406638.2014.918889] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Reported herein is the use of proximity-induced non-covalent energy transfer for the detection of medium-sized polycyclic aromatic hydrocarbons (PAHs). This energy transfer occurs within the cavity of γ-cyclodextrin in various aqueous environments, including human plasma and coconut water. Highly efficient energy transfer was observed, and the efficiency of the energy transfer is independent of the concentration of γ-cyclodextrin used, demonstrating the importance of hydrophobic binding in facilitating such energy transfer. Low limits of detection were also observed for many of the PAHs investigated, which is promising for the development of fluorescence-based detection schemes.
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Affiliation(s)
- Nicole Serio
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
| | - Lindsey Prignano
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
| | - Sean Peters
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
| | - Mindy Levine
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
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11
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Vrtis KB, Markiewicz RP, Romano LJ, Rueda D. Carcinogenic adducts induce distinct DNA polymerase binding orientations. Nucleic Acids Res 2013; 41:7843-53. [PMID: 23814187 PMCID: PMC3763543 DOI: 10.1093/nar/gkt554] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 05/15/2013] [Accepted: 05/24/2013] [Indexed: 12/18/2022] Open
Abstract
DNA polymerases must accurately replicate DNA to maintain genome integrity. Carcinogenic adducts, such as 2-aminofluorene (AF) and N-acetyl-2-aminofluorene (AAF), covalently bind DNA bases and promote mutagenesis near the adduct site. The mechanism by which carcinogenic adducts inhibit DNA synthesis and cause mutagenesis remains unclear. Here, we measure interactions between a DNA polymerase and carcinogenic DNA adducts in real-time by single-molecule fluorescence. We find the degree to which an adduct affects polymerase binding to the DNA depends on the adduct location with respect to the primer terminus, the adduct structure and the nucleotides present in the solution. Not only do the adducts influence the polymerase dwell time on the DNA but also its binding position and orientation. Finally, we have directly observed an adduct- and mismatch-induced intermediate state, which may be an obligatory step in the DNA polymerase proofreading mechanism.
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Affiliation(s)
- Kyle B. Vrtis
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA and Department of Medicine, Section of Virology, Imperial College London, London W12 0NN, UK
| | - Radoslaw P. Markiewicz
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA and Department of Medicine, Section of Virology, Imperial College London, London W12 0NN, UK
| | - Louis J. Romano
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA and Department of Medicine, Section of Virology, Imperial College London, London W12 0NN, UK
| | - David Rueda
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA and Department of Medicine, Section of Virology, Imperial College London, London W12 0NN, UK
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12
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Schmidt HF, Sakowski EG, Williamson SJ, Polson SW, Wommack KE. Shotgun metagenomics indicates novel family A DNA polymerases predominate within marine virioplankton. ISME JOURNAL 2013; 8:103-14. [PMID: 23985748 DOI: 10.1038/ismej.2013.124] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 06/07/2013] [Accepted: 06/18/2013] [Indexed: 02/07/2023]
Abstract
Virioplankton have a significant role in marine ecosystems, yet we know little of the predominant biological characteristics of aquatic viruses that influence the flow of nutrients and energy through microbial communities. Family A DNA polymerases, critical to DNA replication and repair in prokaryotes, are found in many tailed bacteriophages. The essential role of DNA polymerase in viral replication makes it a useful target for connecting viral diversity with an important biological feature of viruses. Capturing the full diversity of this polymorphic gene by targeted approaches has been difficult; thus, full-length DNA polymerase genes were assembled out of virioplankton shotgun metagenomic sequence libraries (viromes). Within the viromes novel DNA polymerases were common and found in both double-stranded (ds) DNA and single-stranded (ss) DNA libraries. Finding DNA polymerase genes in ssDNA viral libraries was unexpected, as no such genes have been previously reported from ssDNA phage. Surprisingly, the most common virioplankton DNA polymerases were related to a siphovirus infecting an α-proteobacterial symbiont of a marine sponge and not the podoviral T7-like polymerases seen in many other studies. Amino acids predictive of catalytic efficiency and fidelity linked perfectly to the environmental clades, indicating that most DNA polymerase-carrying virioplankton utilize a lower efficiency, higher fidelity enzyme. Comparisons with previously reported, PCR-amplified DNA polymerase sequences indicated that the most common virioplankton metagenomic DNA polymerases formed a new group that included siphoviruses. These data indicate that slower-replicating, lytic or lysogenic phage populations rather than fast-replicating, highly lytic phages may predominate within the virioplankton.
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Affiliation(s)
- Helen F Schmidt
- Department of Plant & Soil Science, College of Marine Studies, Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
| | - Eric G Sakowski
- Department of Plant & Soil Science, College of Marine Studies, Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
| | | | - Shawn W Polson
- Department of Plant & Soil Science, College of Marine Studies, Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
| | - K Eric Wommack
- Department of Plant & Soil Science, College of Marine Studies, Delaware Biotechnology Institute, University of Delaware, Newark, DE, USA
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13
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Kuska MS, Witham AA, Sproviero M, Manderville RA, Majdi Yazdi M, Sharma P, Wetmore SD. Structural Influence of C8-Phenoxy-Guanine in the NarI Recognition DNA Sequence. Chem Res Toxicol 2013; 26:1397-408. [DOI: 10.1021/tx400252g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Michael S. Kuska
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Aaron A. Witham
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Michael Sproviero
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Richard A. Manderville
- Departments
of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Mohadeseh Majdi Yazdi
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
| | - Purshotam Sharma
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
| | - Stacey D. Wetmore
- Department
of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada T1K 3M4
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14
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Sandineni A, Lin B, MacKerell AD, Cho BP. Structure and thermodynamic insights on acetylaminofluorene-modified deletion DNA duplexes as models for frameshift mutagenesis. Chem Res Toxicol 2013; 26:937-51. [PMID: 23688347 DOI: 10.1021/tx400116n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
2-Acetylaminofluorene (AAF) is a prototype arylamine carcinogen that forms C8-substituted dG-AAF and dG-AF as the major DNA lesions. The bulky N-acetylated dG-AAF lesion can induce various frameshift mutations depending on the base sequence around the lesion. We hypothesized that the thermodynamic stability of bulged-out slipped mutagenic intermediates (SMIs) is directly related to deletion mutations. The objective of the present study was to probe the structural/conformational basis of various dG-AAF-induced SMIs formed during translesion synthesis. We performed spectroscopic, thermodynamic, and molecular dynamics studies of several AAF-modified 16-mer model DNA duplexes, including fully paired and -1, -2, and -3 deletion duplexes of the 5'-CTCTCGATG[FAAF]CCATCAC-3' sequence and an additional -1 deletion duplex of the 5'-CTCTCGGCG[FAAF]CCATCAC-3' NarI sequence. Modified deletion duplexes existed in a mixture of external B and stacked S conformers, with the population of the S conformer being 'GC'-1 (73%) > 'AT'-1 (72%) > full (60%) > -2 (55%) > -3 (37%). Thermodynamic stability was in the order of -1 deletion > -2 deletion > fully paired > -3 deletion duplexes. These results indicate that the stacked S-type conformer of SMIs is thermodynamically more stable than the conformationally flexible external B conformer. Results from the molecular dynamics simulations indicate that perturbation of base stacking dominates the relative stability along with contributions from bending, duplex dynamics, and solvation effects that are important in specific cases. Taken together, these results support a hypothesis that the conformational and thermodynamic stabilities of the SMIs are critical determinants for the induction of frameshift mutations.
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Affiliation(s)
- Anusha Sandineni
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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15
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Sharma P, Manderville RA, Wetmore SD. Modeling the conformational preference of the carbon-bonded covalent adduct formed upon exposure of 2'-deoxyguanosine to ochratoxin A. Chem Res Toxicol 2013; 26:803-16. [PMID: 23560542 DOI: 10.1021/tx4000864] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The conformational flexibility of the C8-linked guanine adduct formed from attachment of ochratoxin A (OTA) was analyzed using a systematic computational approach and models ranging from the nucleobase to the adducted DNA helix. A focus was placed on the influence of the C8-modification of 2'-deoxyguanosine (dG) on the preferred relative arrangement of the nucleobase and the C8-substituent and, more importantly, the anti/syn conformational preference with respect to the glycosidic bond. Although OTA is twisted with respect to the base in the nucleobase model, addition of the deoxyribose sugar induces a further twist and restricts rotation about the C-C linkage due to close contacts between OTA and the sugar. The nucleoside model preferentially adpots a syn orientation (by 10-20 kJ mol(-1) depending on the OTA conformation) due to the presence of an O5'-H···N3 interaction. However, when this hydrogen bond is eliminated, which better mimics the DNA environment, a small (<5 kJ mol(-1)) anti/syn energy difference is predicted. Inclusion of the 5'-monophosphate group leads to an up to 20 kJ mol(-1) preference for the syn (nucleotide) conformation due to stabilizing base-phosphate interactions involving the amino group of guanine. Nevertheless, MD simulations and free energy analysis predict that both syn- and anti-conformations of OTB-dG are equally stable in helices when paired opposite cytosine. These results indicate that the adduct will likely adopt a syn conformation in an isolated nucleoside and nucleotide, while a mixture of syn and anti conformations will be observed in DNA duplexes. Since the syn conformation could stabilize base mismatches upon DNA replication or Z-DNA structures with varied biological outcomes, future computational and experimental work should elucidate the consequences of the conformational preference of this potentially harmful DNA lesion.
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Affiliation(s)
- Purshotam Sharma
- Department of Chemistry and Biochemistry, University of Lethbridge , 4401 University Drive West, Lethbridge, Alberta T1K 3M4, Canada
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16
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C8-linked bulky guanosine DNA adducts: experimental and computational insights into adduct conformational preferences and resulting mutagenicity. Future Med Chem 2012; 4:1981-2007. [PMID: 23088278 DOI: 10.4155/fmc.12.138] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Bulky DNA adducts are formed through the covalent attachment of aryl groups to the DNA nucleobases. Many of these adducts are known to possess conformational heterogeneity, which is responsible for the variety of mutagenic outcomes associated with these lesions. The present contribution reviews several conformational and mutagenic themes that are prevalent among the DNA adducts formed at the C8-site of the guanine nucleobase. The most important conclusions obtained (to date) from experiments are summarized including the anti/syn conformational preference of the adducts, their potential to inflict DNA mutations and mismatch stabilization, and their interactions with DNA polymerases and repair enzymes. Additionally, the unique role that computer calculations can play in understanding the structural properties of these adducts are highlighted.
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17
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Mu H, Kropachev K, Wang L, Zhang L, Kolbanovskiy A, Kolbanovskiy M, Geacintov NE, Broyde S. Nucleotide excision repair of 2-acetylaminofluorene- and 2-aminofluorene-(C8)-guanine adducts: molecular dynamics simulations elucidate how lesion structure and base sequence context impact repair efficiencies. Nucleic Acids Res 2012; 40:9675-90. [PMID: 22904073 PMCID: PMC3479214 DOI: 10.1093/nar/gks788] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Nucleotide excision repair (NER) efficiencies of DNA lesions can vary by orders of magnitude, for reasons that remain unclear. An example is the pair of N-(2′-deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF) and N-(2′-deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF) adducts that differ by a single acetyl group. The NER efficiencies in human HeLa cell extracts of these lesions are significantly different when placed at G1, G2 or G3 in the duplex sequence (5′-CTCG1G2CG3CCATC-3′) containing the NarI mutational hot spot. Furthermore, the dG-C8-AAF adduct is a better substrate of NER than dG-C8-AF in all three NarI sequence contexts. The conformations of each of these adducts were investigated by Molecular dynamics (MD) simulation methods. In the base-displaced conformational family, the greater repair susceptibility of dG-C8-AAF in all sequences stems from steric hindrance effects of the acetyl group which significantly diminish the adduct-base stabilizing van der Waals stacking interactions relative to the dG-C8-AF case. Base sequence context effects for each adduct are caused by differences in helix untwisting and minor groove opening that are derived from the differences in stacking patterns. Overall, the greater NER efficiencies are correlated with greater extents of base sequence-dependent local untwisting and minor groove opening together with weaker stacking interactions.
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Affiliation(s)
- Hong Mu
- Department of Biology, New York University, 100 Washington Square East, New York, NY 10003, USA
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18
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Vaidyanathan VG, Xu L, Cho BP. Binary and ternary binding affinities between exonuclease-deficient Klenow fragment (Kf-exo(-)) and various arylamine DNA lesions characterized by surface plasmon resonance. Chem Res Toxicol 2012; 25:1568-70. [PMID: 22804627 DOI: 10.1021/tx300289d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We used surface plasmon resonance (SPR) to characterize the binding interactions between the exonulease-free Klenow fragment (Kf-exo(-)) and unmodified and modified dG adducts derived from arylamine carcinogens: fluorinated 2-aminofluorene (FAF), 2-acetylaminofluorene (FAAF), and 4-aminobiphenyl (FABP). Tight polymerase binding was detected with unmodified dG and the correct dCTP. The discrimination of correct versus incorrect nucleotides was pronounced with K(D) values in the order of dCTP ≪ dTTP < dATP < dGTP. In contrast, minimal selectivity was observed for the modified templates with Kf-exo(-) binding tighter to the FAAF (k(off): 0.02 s(-1)) and FABP (k(off): 0.01 s(-1)) lesions than to FAF (k(off): 0.04 s(-1)).
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Affiliation(s)
- V G Vaidyanathan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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19
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Vaidyanathan VG, Cho BP. Sequence Effects on Translesion Synthesis of an Aminofluorene–DNA Adduct: Conformational, Thermodynamic, and Primer Extension Kinetic Studies. Biochemistry 2012; 51:1983-95. [DOI: 10.1021/bi2017443] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- V. G. Vaidyanathan
- Department of Biomedical and Pharmaceutical
Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Bongsup P. Cho
- Department of Biomedical and Pharmaceutical
Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
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20
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Nafisi S, Bonsaii M, Alexis V, Glick J. Binding of 2-Acetylaminofluorene to DNA. DNA Cell Biol 2011; 30:955-62. [DOI: 10.1089/dna.2011.1229] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Shohreh Nafisi
- Department of Chemistry, Central Tehran Branch (IAUCTB), Islamic Azad University, Tehran, Iran
| | - Mahyar Bonsaii
- Department of Chemistry, Central Tehran Branch (IAUCTB), Islamic Azad University, Tehran, Iran
| | - Valerie Alexis
- Chemistry and Chemical Biology Department, Northeastern University, Boston, Massachusetts
| | - James Glick
- Chemistry and Chemical Biology Department, Northeastern University, Boston, Massachusetts
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21
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Shamovsky I, Ripa L, Börjesson L, Mee C, Nordén B, Hansen P, Hasselgren C, O’Donovan M, Sjö P. Explanation for Main Features of Structure–Genotoxicity Relationships of Aromatic Amines by Theoretical Studies of Their Activation Pathways in CYP1A2. J Am Chem Soc 2011; 133:16168-85. [DOI: 10.1021/ja206427u] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Igor Shamovsky
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Lena Ripa
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Lena Börjesson
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Christine Mee
- Genetic Toxicology, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom
| | - Bo Nordén
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | - Peter Hansen
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
| | | | - Mike O’Donovan
- Genetic Toxicology, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom
| | - Peter Sjö
- Department of Medicinal Chemistry, R&I iMed, AstraZeneca R&D, Pepparedsleden 1, S-431 83 Mölndal, Sweden
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22
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Banerjee S, Brown KL, Egli M, Stone MP. Bypass of aflatoxin B1 adducts by the Sulfolobus solfataricus DNA polymerase IV. J Am Chem Soc 2011; 133:12556-68. [PMID: 21790157 PMCID: PMC3154525 DOI: 10.1021/ja2015668] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aflatoxin B(1) (AFB(1)) is oxidized to an epoxide in vivo, which forms an N7-dG DNA adduct (AFB(1)-N7-dG). The AFB(1)-N7-dG can rearrange to a formamidopyrimidine (AFB(1)-FAPY) derivative. Both AFB(1)-N7-dG and the β-anomer of the AFB(1)-FAPY adduct yield G→T transversions in Escherichia coli, but the latter is more mutagenic. We show that the Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) bypasses AFB(1)-N7-dG in an error-free manner but conducts error-prone replication past the AFB(1)-FAPY adduct, including misinsertion of dATP, consistent with the G→T mutations observed in E. coli. Three ternary (Dpo4-DNA-dNTP) structures with AFB(1)-N7-dG adducted template:primers have been solved. These demonstrate insertion of dCTP opposite the AFB(1)-N7-dG adduct, and correct vs incorrect insertion of dATP vs dTTP opposite the 5'-template neighbor dT from a primed AFB(1)-N7-dG:dC pair. The insertion of dTTP reveals hydrogen bonding between the template N3 imino proton and the O(2) oxygen of dTTP, and between the template T O(4) oxygen and the N3 imino proton of dTTP, perhaps explaining why this polymerase does not efficiently catalyze phosphodiester bond formation from this mispair. The AFB(1)-N7-dG maintains the 5'-intercalation of the AFB(1) moiety observed in DNA. The bond between N7-dG and C8 of the AFB(1) moiety remains in plane with the alkylated guanine, creating a 16° inclination of the AFB(1) moiety with respect to the guanine. A binary (Dpo4-DNA) structure with an AFB(1)-FAPY adducted template:primer also maintains 5'-intercalation of the AFB(1) moiety. The β-deoxyribose anomer is observed. Rotation about the FAPY C5-N(5) bond orients the bond between N(5) and C8 of the AFB(1) moiety out of plane in the 5'-direction, with respect to the FAPY base. The formamide group extends in the 3'-direction. This improves stacking of the AFB(1) moiety above the 5'-face of the FAPY base, as compared to the AFB(1)-N7-dG adduct. Ternary structures with AFB(1)-β-FAPY adducted template:primers show correct vs incorrect insertion of dATP vs dTTP opposite the 5'-template neighbor dT from a primed AFB(1)-β-FAPY:dC pair. For dATP, the oxygen atom of the FAPY formamide group participates in a water-mediated hydrogen bond with Arg332. The insertion of dTTP yields a structure similar to that observed for the AFB(1)-N7-dG adduct. The differential accommodation of these AFB(1) adducts within the active site may, in part, modulate lesion bypass.
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Affiliation(s)
- Surajit Banerjee
- Department of Chemistry, Center in Molecular Toxicology, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
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23
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Liang F, Cho BP. Conformational and thermodynamic impact of bulky aminofluorene adduction on simulated translesion DNA synthesis. Chem Res Toxicol 2011; 24:597-605. [PMID: 21410284 DOI: 10.1021/tx2000587] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We report a systematic spectroscopic investigation on the conformational evolution during primer extension of a bulky fluoroaminofluorene-modified dG adduct (FAF-dG) in chemically simulated translesion synthesis. FAF-dG was paired either with dC or dA (dC-match and dA-mismatch series, respectively). Dynamic (19)F NMR/CD results showed that the FAF-adduct exists in a syn/anti equilibrium and that its conformational characteristics are modulated by the identity of an inserted nucleotide at the lesion site and the extent of primer elongation. At the pre-insertion site, the adduct adopted preferentially a syn conformation where FAF stacked with preceding bases. Insertion of the correct nucleotide dC at the lesion site and subsequent elongation resulted in a gradual transition to the anti conformation. By contrast, the syn conformer was persistent along with primer extension in the dA-mismatch series. In the dC-match series, FAF-induced thermal (T(m)) and thermodynamic (-ΔG°(37 °C)) stabilities were significantly reduced relative to those of the controls. However, the corresponding T(m) and -ΔG°(37 °C) values were increased in the FAF-modified mismatched dA series. The lesion impact persisted up to three 5'-nucleotides from the lesion. Occupation of the minor groove of the W-conformer with the bulky carcinogenic fluorene moiety not only would limit the DNA mobility but also would impose a serious difficulty for the active site of a polymerase throughout the replication process. Our spectroscopic results are consistent with reported data on AF, which showed dramatic (~10(4)-fold) differences in the nucleotide insertion rates between the dC-match and dA-mismatch series. The results emphasize the importance of adduct-induced steric constraints for determining the replication fidelity of a polymerase.
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Affiliation(s)
- Fengting Liang
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, United States
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24
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Mechanism of replication blocking and bypass of Y-family polymerase {eta} by bulky acetylaminofluorene DNA adducts. Proc Natl Acad Sci U S A 2010; 107:20720-5. [PMID: 21076032 DOI: 10.1073/pnas.1008894107] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterocyclic aromatic amines produce bulky C8 guanine lesions in vivo, which interfere and disrupt DNA and RNA synthesis. These lesions are consequently strong replication blocks. In addition bulky adducts give rise to point and frameshift mutations. The translesion synthesis (TLS) DNA polymerase η is able to bypass slowly C8 bulky adduct lesions such as the widely studied 2-aminofluorene-dG and its acetylated analogue mainly in an error-free manner. Replicative polymerases are in contrast fully blocked by the acetylated lesion. Here, we show that TLS efficiency of Pol η depends critically on the size of the bulky adduct forming the lesion. Based on the crystal structure, we show why the bypass reaction is so difficult and we provide a model for the bypass reaction. In our model, TLS is accomplished without rotation of the lesion into the anti conformation as previously thought.
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25
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Federley RG, Romano LJ. DNA polymerase: structural homology, conformational dynamics, and the effects of carcinogenic DNA adducts. J Nucleic Acids 2010; 2010. [PMID: 20847947 PMCID: PMC2933918 DOI: 10.4061/2010/457176] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Accepted: 06/30/2010] [Indexed: 01/05/2023] Open
Abstract
DNA replication is vital for an organism to proliferate and lying at the heart of this process is the enzyme DNA polymerase. Most DNA polymerases have a similar three dimensional fold, akin to a human right hand, despite differences in sequence homology. This structural homology would predict a relatively unvarying mechanism for DNA synthesis yet various polymerases exhibit markedly different properties on similar substrates, indicative of each type of polymerase being prescribed to a specific role in DNA replication. Several key conformational steps, discrete states, and structural moieties have been identified that contribute to the array of properties the polymerases exhibit. The ability of carcinogenic adducts to interfere with conformational processes by directly interacting with the protein explicates the mutagenic consequences these adducts impose. Recent studies have identified novel states that have been hypothesised to test the fit of the nascent base pair, and have also shown the enzyme to possess a lively quality by continually sampling various conformations. This review focuses on the homologous structural changes that take place in various DNA polymerases, both replicative and those involved in adduct bypass, the role these changes play in selection of a correct substrate, and how the presence of bulky carcinogenic adducts affects these changes.
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26
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Rechkoblit O, Kolbanovskiy A, Malinina L, Geacintov NE, Broyde S, Patel DJ. Mechanism of error-free and semitargeted mutagenic bypass of an aromatic amine lesion by Y-family polymerase Dpo4. Nat Struct Mol Biol 2010; 17:379-88. [PMID: 20154704 PMCID: PMC4215948 DOI: 10.1038/nsmb.1771] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 12/09/2009] [Indexed: 12/22/2022]
Abstract
The aromatic amine carcinogen 2-aminofluorene (AF) forms covalent adducts with DNA, predominantly with guanine at the C8 position. Such lesions are bypassed by Y-family polymerases such as Dpo4 via error-free and error-prone mechanisms. We show that Dpo4 catalyzes elongation from a correct 3′-terminal C opposite [AF]G in a nonrepetitive template sequence with low efficiency. This extension leads to cognate full-length product, as well as mis-elongated products containing base mutations and deletions. Crystal structures of the Dpo4 ternary complex with the 3′-terminal primer C base opposite [AF]G in the anti conformation and with the AF-moiety positioned in the major groove, revealed both accurate and misalignment-mediated mutagenic extension pathways. The mutagenic template/primer-dNTP arrangement is promoted by interactions between the polymerase and the bulky lesion, rather than by a base pairstabilized misaligment. Further extension leads to semi-targeted mutations via this proposed polymerase-guided mechanism.
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Affiliation(s)
- Olga Rechkoblit
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
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27
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Liang F, Cho BP. Enthalpy-entropy contribution to carcinogen-induced DNA conformational heterogeneity. Biochemistry 2010; 49:259-66. [PMID: 19961237 DOI: 10.1021/bi901629p] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA damage by adduct formation is a critical step for the initiation of carcinogenesis. Aromatic amines are strong inducers of environmental carcinogenesis. Their DNA adducts are known to exist in an equilibrium between the major groove (B) and base-displaced stacked (S) conformations. However, the factors governing such heterogeneity remain unclear. Here we conducted extensive calorimetry/NMR/CD studies on the model DNA lesions caused by fluorinated 2-aminfluorene (FAF) and 4-aminobiphenyl (FABP) in order to gain thermodynamic and kinetic insights into the S/B conformational equilibrium. We demonstrate that there are large differences in enthalpy-entropy compensations for FABP and FAF. The small and flexible FABP exclusively adopts the less perturbed B conformer with small enthalpy (DeltaDeltaH-2.7 kcal/mol)/entropy (DeltaDeltaS-0.7 eu) change. In contrast, FAF stacks better and exists as a mixture of B and S conformers with large enthalpy (DeltaDeltaH-13.4 kcal/mol)/entropy (DeltaDeltaS-34.2 eu) compensation. van't Hoff analysis of dynamic (19)F NMR data indicated DeltaH(B<-->S) = 4.1 kcal/mol in favor of the B conformer and DeltaS(B<-->S) = 15.6 cal mol(-1) K(-1) in favor of the intercalated S conformer. These findings demonstrate that the favorable entropy of the S conformer over B conformer determines the S/B population ratios at physiological temperatures.
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Affiliation(s)
- Fengting Liang
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island 02881, USA
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28
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Abstract
Replisomes are the protein assemblies that replicate DNA. They function as molecular motors to catalyze template-mediated polymerization of nucleotides, unwinding of DNA, the synthesis of RNA primers, and the assembly of proteins on DNA. The replisome of bacteriophage T7 contains a minimum of proteins, thus facilitating its study. This review describes the molecular motors and coordination of their activities, with emphasis on the T7 replisome. Nucleotide selection, movement of the polymerase, binding of the processivity factor, unwinding of DNA, and RNA primer synthesis all require conformational changes and protein contacts. Lagging-strand synthesis is mediated via a replication loop whose formation and resolution is dictated by switches to yield Okazaki fragments of discrete size. Both strands are synthesized at identical rates, controlled by a molecular brake that halts leading-strand synthesis during primer synthesis. The helicase serves as a reservoir for polymerases that can initiate DNA synthesis at the replication fork. We comment on the differences in other systems where applicable.
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Affiliation(s)
- Samir M Hamdan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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29
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Rescue of bacteriophage T7 DNA polymerase of low processivity by suppressor mutations affecting gene 3 endonuclease. J Virol 2009; 83:8418-27. [PMID: 19535436 DOI: 10.1128/jvi.00855-09] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The DNA polymerase encoded by gene 5 (gp5) of bacteriophage T7 has low processivity, dissociating after the incorporation of a few nucleotides. Upon binding to its processivity factor, Escherichia coli thioredoxin (Trx), the processivity is increased to approximately 800 nucleotides per binding event. Several interactions between gp5/Trx and DNA are required for processive DNA synthesis. A basic region in T7 DNA polymerase (residues K587, K589, R590, and R591) is located in proximity to the 5' overhang of the template strand. Replacement of these residues with asparagines results in a threefold reduction of the polymerization activity on primed M13 single-stranded DNA. The altered gp5/Trx exhibits a 10-fold reduction in its ability to support growth of T7 phage lacking gene 5. However, T7 phages that grow at a similar rate provided with either wild-type or altered polymerase emerge. Most of the suppressor phages contain genetic changes in or around the coding region for gene 3, an endonuclease. Altered gene 3 proteins derived from suppressor strains show reduced catalytic activity and are inefficient in complementing growth of T7 phage lacking gene 3. Results from this study reveal that defects in processivity of DNA polymerase can be suppressed by reducing endonuclease activity.
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30
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Vooradi V, Romano LJ. Effect of N-2-acetylaminofluorene and 2-aminofluorene adducts on DNA binding and synthesis by yeast DNA polymerase eta. Biochemistry 2009; 48:4209-16. [PMID: 19354292 DOI: 10.1021/bi9000722] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The well-studied aromatic amine carcinogen, N-2-acetylaminofluorene (AAF), forms adducts at the C8 position of guanine in DNA. Unlike replicative polymerases, Y-family polymerases have been shown to have the ability to bypass such bulky DNA lesions. To better understand the mechanism of translesion synthesis by the yeast DNA polymerase eta (yPoleta), a gel retardation technique was used to measure equilibrium dissociation constants of this polymerase for unmodified DNA or DNA containing dG-C8-AAF or the related deacylated dG-C8-AF adduct. These results show that the binding of yPoleta to the unmodified primer-template is substantially stronger in the presence of the next correct nucleotide than when no or an incorrect nucleotide is present. In addition, binding of yPoleta to either dG-C8-AAF or AF-modified templates is also stronger in the presence of dCTP. Finally, the yPoleta complex is destabilized if the primer extends to a position across from the adduct, and stronger binding is not observed in the presence of the next correct nucleotide. Taken together, these data are consistent with the ability of yPoleta to undergo a conformational change to a closed ternary complex in the presence of the next correct nucleotide and on templates containing an AAF or AF adduct but do not rule out other possible explanations.
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31
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Crystal structure analysis of DNA lesion repair and tolerance mechanisms. Curr Opin Struct Biol 2009; 19:87-95. [DOI: 10.1016/j.sbi.2009.01.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 01/12/2009] [Accepted: 01/16/2009] [Indexed: 12/16/2022]
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32
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33
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Burnouf DY, Wagner JE. Kinetics of deoxy-CTP incorporation opposite a dG-C8-N-2-aminofluorene adduct by a high-fidelity DNA polymerase. J Mol Biol 2009; 386:951-61. [PMID: 19150355 DOI: 10.1016/j.jmb.2008.12.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 12/18/2008] [Accepted: 12/22/2008] [Indexed: 11/28/2022]
Abstract
The model carcinogen N-2-acetylaminofluorene covalently binds to the C8 position of guanine to form two adducts, the N-(2'-deoxyguanosine-8-yl)-aminofluorene (G-AF) and the N-2-(2'-deoxyguanosine-8-yl)-acetylaminofluorene (G-AAF). Although they are chemically closely related, their biological effects are strongly different and they are processed by different damage tolerance pathways. G-AF is bypassed by replicative and high-fidelity polymerases, while specialized polymerases ensure synthesis past of G-AAF. We used the DNA polymerase I fragment of a Bacillus stearothermophilus strain as a model for a high-fidelity polymerase to study the kinetics of incorporation of deoxy-CTP (dCTP) opposite a single G-AF. Pre-steady-state kinetic experiments revealed a drastic reduction in dCTP incorporation performed by the G-AF-modified ternary complex. Two populations of these ternary complexes were identified: (i) a minor productive fraction (20%) that readily incorporates dCTP opposite the G-AF adduct with a rate similar to that measured for the adduct-free ternary complexes and (ii) a major fraction of unproductive complexes (80%) that slowly evolve into productive ones. In the light of structural data, we suggest that this slow rate reflects the translocation of the modified base within the active site, from the pre-insertion site into the insertion site. By making this translocation rate limiting, the G-AF lesion reveals a novel kinetic step occurring after dNTP binding and before chemistry.
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Affiliation(s)
- Dominique Y Burnouf
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC du Centre National de la Recherche Scientifique, 15 rue René Descartes, 67084 Strasbourg, France.
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34
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Stankevicins L, Aiub C, Maria LDS, Lobo-Hajdu G, Felzenszwalb I. Genotoxic and antigenotoxic evaluation of extracts from Arenosclera brasiliensis, a Brazilian marine sponge. Toxicol In Vitro 2008; 22:1869-77. [DOI: 10.1016/j.tiv.2008.09.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 08/25/2008] [Accepted: 09/08/2008] [Indexed: 10/21/2022]
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35
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Jain N, Reshetnyak YK, Gao L, Chiarelli MP, Cho BP. Fluorescence probing of aminofluorene-induced conformational heterogeneity in DNA duplexes. Chem Res Toxicol 2008; 21:445-52. [PMID: 18193841 DOI: 10.1021/tx7003536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fluorescence spectroscopy was used to study carcinogen-induced conformational heterogeneity in DNA duplexes. The fluorophore 2-aminopurine (AP) was incorporated adjacent (5') to the lesion (G*) in eight different DNA duplexes [d(5'-CTTCT PG* NCCTC-3'):d(5'-GAGGN XTAGAAG-3'), G* = FAF adduct, P = AP, N = G, A, C, T, and X = C, A] modified by FAF [ N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene], a fluorine-tagged model DNA adduct derived from the potent carcinogen 2-aminofluorene. Steady-state measurements showed that fluorescence intensity and Stern-Volmer constants ( Ksv) derived from acrylamide quenching experiments decreased for all carcinogen-modified duplexes relative to the controls, which suggests greater AP stacking in the duplex upon adduct formation. Conformation-specific stacking of AP with the neighboring adduct was evidenced by a sequence-dependent variation in fluorescence intensity, position of emission maximum, degree of emission quenching by acrylamide, and temperature-dependent spectral changes. The magnitude of stacking was in the order of FAF residue in base-displaced stacked (S) > minor groove wedged (W) > major groove B type (B). This work represents a novel utility of AP in probing adduct-induced conformational heterogeneities in DNA duplexes.
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Affiliation(s)
- Nidhi Jain
- Department of Biomedical and Pharmaceutical Sciences and Physics, University of Rhode Island, Kingston, RI 02881, USA
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36
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Broyde S, Wang L, Zhang L, Rechkoblit O, Geacintov NE, Patel DJ. DNA adduct structure-function relationships: comparing solution with polymerase structures. Chem Res Toxicol 2007; 21:45-52. [PMID: 18052109 DOI: 10.1021/tx700193x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
It has now been nearly two decades since the first solution structures of DNA duplexes covalently damaged by metabolically activated polycyclic aromatic hydrocarbons and amines were determined by NMR. Dozens of such high-resolution structures are now available, and some broad structural themes have been uncovered. It has been hypothesized that the solution structures are relevant to the biochemical processing of the adducts. The structural features of the adducts are considered to determine their mutational properties in DNA polymerases and their repair susceptibilities. In recent years, a number of crystal structures of DNA adducts of interest to our work have been determined in DNA polymerases. Accordingly, it is now timely to consider how NMR solution structures relate to structures within DNA polymerases. The NMR solution structural themes for polycyclic aromatic adducts are often observed in polymerase crystal structures. While the polymerase interactions can on occasion override the solution preferences, intrinsic adduct conformations favored in solution are often manifested within polymerases and likely play a significant role in lesion processing.
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Affiliation(s)
- Suse Broyde
- Department of Biology, New York University, New York NY 10003, USA.
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37
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Jain N, Li Y, Zhang L, Meneni SR, Cho BP. Probing the sequence effects on NarI-induced -2 frameshift mutagenesis by dynamic 19F NMR, UV, and CD spectroscopy. Biochemistry 2007; 46:13310-21. [PMID: 17960913 DOI: 10.1021/bi701386f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The NarI recognition sequence (5'-G1G2CG3CN-3') is the most vulnerable hot spot for frameshift mutagenesis induced by the carcinogen 2-aminofluorene and its analogues in Escherichia coli. Lesioning of the guanine in the G3 position induces an especially high frequency of -2 deletion mutations; vulnerability to these mutations is modulated by the nature of the nucleotide in the N position (C approximately A > G > T). The objective of the present study was to probe the structural basis of this N-mediated influence on the propensity of the G3 lesion to form a slipped mutagenic intermediate (SMI) during translesion synthesis. We studied NarI-based fully paired [(5'-CTCG1G2CG3*CNATC-3')(5'-GATNCGGCCGAG-3'), N = dC or dT] and -2 deletion [(5'-CTCG1G2CG3*CNATC-3')(5'-GATNGCCGAG-3'), N = dC or dT] duplexes, in which G* was either AF [N-(2'-deoxyguanosin-8-yl)-2-aminofluorene] or the 19F probe FAF [N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene]. The latter sequences mimic the bulged SMI for -2 deletion mutations. Dynamic 19F NMR, circular dichroism, and UV melting results indicated that the NarI-dC/-2 deletion duplex adopts exclusively an intercalated conformer, whereas the NarI-dT/-2 deletion duplex exists as multiple conformers. The data support the presence of a putative equilibrium between a carcinogen-intercalated and a carcinogen-exposed SMI for the dT/-2 duplex. A similar dT-induced conformational heterogeneity was observed for the fully paired duplexes in which all three guanines were individually modified by AF or FAF. The frequency of the carcinogen stacked S-conformation was found to be highest (69-75%) at the G3 hot spot in NarI-dC duplexes. Taken together, our results support the hypothesis that the conformational stability of the SMI is a critical determinant for the efficacy of -2 frameshift mutagenesis in the NarI sequence. We also provide evidence for AF/FAF conformational compatibility in the NarI sequences.
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Affiliation(s)
- Nidhi Jain
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, USA
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Wang F, Elmquist CE, Stover JS, Rizzo CJ, Stone MP. DNA sequence modulates the conformation of the food mutagen 2-amino-3-methylimidazo[4,5-f]quinoline in the recognition sequence of the NarI restriction enzyme. Biochemistry 2007; 46:8498-516. [PMID: 17602664 PMCID: PMC2782574 DOI: 10.1021/bi700361u] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The conformations of C8-dG adducts of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) positioned in the C-X1-G, G-X2-C, and C-X3-C contexts in the C-G1-G2-C-G3-C-C recognition sequence of the NarI restriction enzyme were compared, using the oligodeoxynucleotides 5'-d(CTCXGCGCCATC)-3'.5'-d(GATGGCGCCGAG)-3', 5'-d(CTCGXCGCCATC)-3'.5'-d(GATGGCGCCGAG)-3', and 5'-d(CTCGGCXCCATC)-3'.5'-d(GATGGCGCCGAG)-3' (X is the C8-dG adduct of IQ). These were the NarIIQ1, NarIIQ2, and NarIIQ3 duplexes, respectively. In each instance, the glycosyl torsion angle chi for the IQ-modified dG was in the syn conformation. The orientations of the IQ moieties were dependent upon the conformations of torsion angles alpha' [N9-C8-N(IQ)-C2(IQ)] and beta' [C8-N(IQ)-C2(IQ)-N3(IQ)], which were monitored by the patterns of 1H NOEs between the IQ moieties and the DNA in the three sequence contexts. The conformational states of IQ torsion angles alpha' and beta' were predicted from the refined structures of the three adducts obtained from restrained molecular dynamics calculations, utilizing simulated annealing protocols. For the NarIIQ1 and NarIIQ2 duplexes, the alpha' torsion angles were predicted to be -176 +/- 8 degrees and -160 +/- 8 degrees , respectively, whereas for the NarIIQ3 duplex, torsion angle alpha' was predicted to be 159 +/- 7 degrees . Likewise, for the NarIIQ1 and NarIIQ2 duplexes, the beta' torsion angles were predicted to be -152 +/- 8 degrees and -164 +/- 7 degrees , respectively, whereas for the NarIIQ3 duplex, torsion angle beta' was predicted to be -23 +/- 8 degrees . Consequently, the conformations of the IQ adduct in the NarIIQ1 and NarIIQ2 duplexes were similar, with the IQ methyl protons and IQ H4 and H5 protons facing outward in the minor groove, whereas in the NarIIQ3 duplex, the IQ methyl protons and the IQ H4 and H5 protons faced into the DNA duplex, facilitating the base-displaced intercalated orientation of the IQ moiety [Wang, F., Elmquist, C. E., Stover, J. S., Rizzo, C. J., and Stone, M. P. (2006) J. Am. Chem. Soc. 128, 10085-10095]. In contrast, for the NarIIQ1 and NarIIQ2 duplexes, the IQ moiety remained in the minor groove. These sequence-dependent differences suggest that base-displaced intercalation of the IQ adduct is favored when both the 5'- and 3'-flanking nucleotides in the complementary strand are guanines. These conformational differences may correlate with sequence-dependent differences in translesion replication.
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Affiliation(s)
| | | | | | - Carmelo J. Rizzo
- To whom correspondence should be addressed. C.J.R.: telephone, (615) 322−6100; fax, (615) 343−1234; e-mail, . M.P.S.: telephone, (615) 322−2589; fax, (615) 322−7591; e-mail,
| | - Michael P. Stone
- To whom correspondence should be addressed. C.J.R.: telephone, (615) 322−6100; fax, (615) 343−1234; e-mail, . M.P.S.: telephone, (615) 322−2589; fax, (615) 322−7591; e-mail,
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Stover JS, Chowdhury G, Zang H, Guengerich FP, Rizzo CJ. Translesion synthesis past the C8- and N2-deoxyguanosine adducts of the dietary mutagen 2-Amino-3-methylimidazo[4,5-f]quinoline in the NarI recognition sequence by prokaryotic DNA polymerases. Chem Res Toxicol 2007; 19:1506-17. [PMID: 17112239 PMCID: PMC3150502 DOI: 10.1021/tx0601455] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
2-Amino-3-methylimidazo[4,5-f]quinoline (IQ) is found in cooked meats and forms DNA adducts at the C8- and N2-positions of dGuo after appropriate activation. IQ is a potent inducer of frameshift mutations in bacteria and is carcinogenic in laboratory animals. We have incorporated both IQ-adducts into the G1- and G3-positions of the NarI recognition sequence (5'-G1G2CG3CC-3'), which is a hotspot for arylamine modification. The in vitro replication of the oligonucleotides was examined with Escherichia coli pol I Klenow fragment exo-, E. coli pol II exo-, and Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4), and the extension products were sequenced by tandem mass spectrometry. Replication of the C8-adduct at the G3-position resulted in two-base deletions with all three polymerases, whereas error-free bypass and extension was observed at the G1-position. The N2-adduct was bypassed and extended by all three polymerases when positioned at the G1-position, and the error-free product was observed. The N2-adduct at the G3-position was more blocking and was bypassed and extended only by Dpo4 to produce an error-free product. These results indicate that the replication of the IQ-adducts of dGuo is strongly influenced by the local sequence and the regioisomer of the adduct. These results also suggest a possible role for pol II and IV in the error-prone bypass of the C8-IQ-adduct leading to frameshift mutations in reiterated sequences, whereas noniterated sequences result in error-free bypass.
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Affiliation(s)
| | | | | | | | - Carmelo J. Rizzo
- Corresponding author. Tel.: (615) 322-6100; fax: (615) 343-1234;
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40
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Elmquist CE, Wang F, Stover JS, Stone MP, Rizzo CJ. Conformational differences of the C8-deoxyguanosine adduct of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) within the NarI recognition sequence. Chem Res Toxicol 2007; 20:445-54. [PMID: 17311423 PMCID: PMC2743555 DOI: 10.1021/tx060229d] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
2-amino-3-methylimidazo[4,5-f]quinoline (IQ) is a highly mutagenic heterocyclic amine found in cooked meats. The major DNA adduct of IQ is at the C8-position of dGuo. We have previously reported the incorporation of the C8-IQ adduct into oligonucleotides, namely, the G1-position of codon 12 of the N-ras oncogene sequence (G1G2T) and the G3-position of the NarI recognition sequence (G1G2CG3CC) (Elmquist et al. (2004) J. Am. Chem. Soc. 126, 11189-11201). Ultraviolet spectroscopy and circular dichroism studies indicated that the conformation of the adduct in the two oligonucleotides was different, and they were assigned as groove-bound and base-displaced intercalated, respectively. The conformation of the latter was subsequently confirmed through NMR and restrained molecular dynamics studies (Wang et al. (2006) J. Am. Chem. Soc. 128, 10085-10095). We report here the incorporation of the C8-IQ adduct into the G1- and G2-positions of the NarI sequence. A complete analysis of the UV, CD, and NMR chemical shift data for the IQ protons are consistent with the IQ adduct adopting a minor groove-bound conformation at the G1- and G2-positions of the NarI sequence. To further correlate the spectroscopic data with the adduct conformation, the C8-aminofluorene (AF) adduct of dGuo was also incorporated into the NarI sequence; previous NMR studies demonstrated that the AF-modified oligonucleotides were in a sequence-dependent conformational exchange between major groove-bound and base-displaced intercalated conformations. The spectroscopic data for the IQ- and AF-modified oligonucleotides are compared. The sequence-dependent conformational preferences are likely to play a key role in the repair and mutagenicity of C8-arylamine adducts.
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Affiliation(s)
| | | | | | - Michael P. Stone
- To whom correspondence should be addressed. Phone: 615-322-6100. Fax: 615-343-1234. E-mail: (C.J.R.). Phone: (615) 322-2589. Fax: (615) 322-7591. E-mail: (M.P.S.)
| | - Carmelo J. Rizzo
- To whom correspondence should be addressed. Phone: 615-322-6100. Fax: 615-343-1234. E-mail: (C.J.R.). Phone: (615) 322-2589. Fax: (615) 322-7591. E-mail: (M.P.S.)
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41
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Meneni S, Liang F, Cho BP. Examination of the long-range effects of aminofluorene-induced conformational heterogeneity and its relevance to the mechanism of translesional DNA synthesis. J Mol Biol 2006; 366:1387-400. [PMID: 17217958 PMCID: PMC1850230 DOI: 10.1016/j.jmb.2006.12.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 12/06/2006] [Accepted: 12/12/2006] [Indexed: 10/23/2022]
Abstract
Adduct-induced conformational heterogeneity complicates the understanding of how DNA adducts exert mutation. A case in point is the N-deacetylated AF lesion [N-(2'-deoxyguanosin-8-yl)-2-aminofluorene], the major adduct derived from the strong liver carcinogen N-acetyl-2-aminofluorene. Three conformational families have been previously characterized and are dependent on the positioning of the aminofluorene rings: B is in the "B-DNA" major groove, S is "stacked" into the helix with base-displacement, and W is "wedged" into the minor groove. Here, we conducted (19)F NMR, CD, T(m), and modeling experiments at various primer positions with respect to a template modified by a fluorine tagged AF-adduct (FAF). In the first set, the FAF-G was paired with C and in the second set it was paired with A. The FAF-G:C oligonucleotides were found to preferentially adopt the B or S-conformers while the FAF-G:A mismatch ones preferred the B and W-conformers. The conformational preferences of both series were dependent on temperature and complementary strand length; the largest differences in conformation were displayed at lower temperatures. The CD and T(m) results are in general agreement with the NMR data. Molecular modeling indicated that the aminofluorene moiety in the minor groove of the W-conformer would impose a steric clash with the tight-packing amino acid residues on the DNA binding area of the Bacillus fragment (BF), a replicative DNA polymerase. In the case of the B-type conformer, the carcinogenic moiety resides in the solvent-exposed major groove throughout the replication/translocation process. The present dynamic NMR results, combined with previous primer extension kinetic data by Miller & Grollman, support a model in which adduct-induced conformational heterogeneities at positions remote from the replication fork affect polymerase function through a long-range DNA-protein interaction.
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Affiliation(s)
| | | | - Bongsup P. Cho
- *Address correspondence to: Bongsup P. Cho, Dept. of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 41 Lower College Road, Kingston, Rhode Island 02881, Tel. 401-874-5024; Fax. 401-874-5766;
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42
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Choi JY, Stover JS, Angel KC, Chowdhury G, Rizzo CJ, Guengerich FP. Biochemical basis of genotoxicity of heterocyclic arylamine food mutagens: Human DNA polymerase eta selectively produces a two-base deletion in copying the N2-guanyl adduct of 2-amino-3-methylimidazo[4,5-f]quinoline but not the C8 adduct at the NarI G3 site. J Biol Chem 2006; 281:25297-306. [PMID: 16835218 DOI: 10.1074/jbc.m605699200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heterocyclic arylamines are highly mutagenic and cause tumors in animal models. The mutagenicity is attributed to the C8- and N2-G adducts, the latter of which accumulates due to slower repair. The C8- and N 2-G adducts derived from 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) were placed at the G1 and G3 sites of the NarI sequence, in which the G3 site is an established hot spot for frameshift mutation with the model arylamine derivative 2-acetylaminofluorene but G1 is not. Human DNA polymerase (pol) eta extended primers beyond template G-IQ adducts better than did pol kappa and much better than pol iota or delta. In 1-base incorporation studies, pol eta inserted C and A, pol iota inserted T, and pol kappa inserted G. Steady-state kinetic parameters were measured for these dNTPs opposite the C8- and N 2-IQ adducts at both sites, being most favorable for pol eta. Mass spectrometry of pol eta extension products revealed a single major product in each of four cases; with the G1 and G3 C8-IQ adducts, incorporation was largely error-free. With the G3 N 2-IQ adduct, a -2 deletion occurred at the site of the adduct. With the G1 N 2-IQ adduct, the product was error-free at the site opposite the base and then stalled. Thus, the pol eta products yielded frame-shifts with the N 2 but not the C8 IQ adducts. We show a role for pol eta and the complexity of different chemical adducts of IQ, DNA position, and DNA polymerases.
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Affiliation(s)
- Jeong-Yun Choi
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232-0146, USA
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43
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
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Rechkoblit O, Malinina L, Cheng Y, Kuryavyi V, Broyde S, Geacintov NE, Patel DJ. Stepwise translocation of Dpo4 polymerase during error-free bypass of an oxoG lesion. PLoS Biol 2006; 4:e11. [PMID: 16379496 PMCID: PMC1325099 DOI: 10.1371/journal.pbio.0040011] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 11/01/2005] [Indexed: 12/02/2022] Open
Abstract
7,8-dihydro-8-oxoguanine (oxoG), the predominant lesion formed following oxidative damage of DNA by reactive oxygen species, is processed differently by replicative and bypass polymerases. Our kinetic primer extension studies demonstrate that the bypass polymerase Dpo4 preferentially inserts C opposite oxoG, and also preferentially extends from the oxoG•C base pair, thus achieving error-free bypass of this lesion. We have determined the crystal structures of preinsertion binary, insertion ternary, and postinsertion binary complexes of oxoG-modified template-primer DNA and Dpo4. These structures provide insights into the translocation mechanics of the bypass polymerase during a complete cycle of nucleotide incorporation. Specifically, during noncovalent dCTP insertion opposite oxoG (or G), the little-finger domain–DNA phosphate contacts translocate by one nucleotide step, while the thumb domain–DNA phosphate contacts remain fixed. By contrast, during the nucleotidyl transfer reaction that covalently incorporates C opposite oxoG, the thumb-domain–phosphate contacts are translocated by one nucleotide step, while the little-finger contacts with phosphate groups remain fixed. These stepwise conformational transitions accompanying nucleoside triphosphate binding and covalent nucleobase incorporation during a full replication cycle of Dpo4-catalyzed bypass of the oxoG lesion are distinct from the translocation events in replicative polymerases. Crystal structures of the bypass polymerase Dpo4 at different stages of lesion-bypass reveal how the cell copes with oxidative DNA damage.
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Affiliation(s)
- Olga Rechkoblit
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Lucy Malinina
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Yuan Cheng
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Vitaly Kuryavyi
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Suse Broyde
- 2Biology Department, New York University, New York, New York, United States of America
| | - Nicholas E Geacintov
- 3Chemistry Department, New York University, New York, New York, United States of America
| | - Dinshaw J Patel
- 1Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
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45
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Garcia-Diaz M, Kunkel TA. Mechanism of a genetic glissando: structural biology of indel mutations. Trends Biochem Sci 2006; 31:206-14. [PMID: 16545956 DOI: 10.1016/j.tibs.2006.02.004] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 01/17/2006] [Accepted: 02/22/2006] [Indexed: 11/30/2022]
Abstract
Insertions and deletions of bases in DNA (collectively termed "indels") are both common and biologically relevant, being associated with different human pathologies including cancer and diseases associated with expansions of repeats. Four decades of research have resulted in several hypotheses regarding how indels are generated during DNA synthesis and how they subsequently undergo or escape correction. Recent structural studies of DNA polymerases bound to mutagenic substrates have increased our understanding of how DNA polymerases cope with abnormal substrates. These structures provide insight into the molecular mechanisms underlying indel generation.
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Affiliation(s)
- Miguel Garcia-Diaz
- Laboratory of Structural Biology and Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA
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Wang L, Broyde S. A new anti conformation for N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (AAF-dG) allows Watson-Crick pairing in the Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4). Nucleic Acids Res 2006; 34:785-95. [PMID: 16452300 PMCID: PMC1360743 DOI: 10.1093/nar/gkj479] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Primer extension studies have shown that the Y-family DNA polymerase IV (Dpo4) from Sulfolobus solfataricus P2 can preferentially insert C opposite N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (AAF-dG) [F. Boudsocq, S. Iwai, F. Hanaoka and R. Woodgate (2001) Nucleic Acids Res., 29, 4607–4616]. Our goal is to elucidate on a structural level how AAF-dG can be harbored in the Dpo4 active site opposite an incoming dCTP, using molecular modeling and molecular dynamics simulations, since AAF-dG prefers the syn glycosidic torsion. Both anti and syn conformations of the templating AAF-dG in a Dpo4 ternary complex were investigated. All four dNTPs were studied. We found that an anti glycosidic torsion with C1′-exo deoxyribose conformation allows AAF-dG to be Watson–Crick hydrogen-bonded with dCTP with modest polymerase perturbation, but other nucleotides are more distorting. The AAF is situated in the Dpo4 major groove open pocket with fluorenyl rings 3′- and acetyl 5′-directed along the modified strand, irrespective of dNTP. With AAF-dG syn, the fluorenyl rings are in the small minor groove pocket and the active site region is highly distorted. The anti-AAF-dG conformation with C1′-exo sugar pucker can explain the preferential incorporation of dC by Dpo4. Possible relevance of our new major groove structure for AAF-dG to other polymerases, lesion repair and solution conformations are discussed.
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Affiliation(s)
| | - Suse Broyde
- To whom all correspondence should be addressed. Tel: +1 212 998 8231; Fax: +1 212 995 4015;
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47
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Meneni SR, D'Mello R, Norigian G, Baker G, Gao L, Chiarelli MP, Cho BP. Sequence effects of aminofluorene-modified DNA duplexes: thermodynamic and circular dichroism properties. Nucleic Acids Res 2006; 34:755-63. [PMID: 16449208 PMCID: PMC1356535 DOI: 10.1093/nar/gkj480] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/14/2005] [Accepted: 01/14/2005] [Indexed: 11/12/2022] Open
Abstract
Circular dichroism (CD) and UV-melting experiments were conducted with 16 oligodeoxynucleotides modified by the carcinogen 2-aminofluorene, whose sequence around the lesion was varied systematically [d(CTTCTNG[AF]NCCTC), N = G, A, C, T], to gain insight into the factors that determine the equilibrium between base-displaced stacked (S) and external B-type (B) duplex conformers. Differing stabilities among the duplexes can be attributed to different populations of S and B conformers. The AF modification always resulted in sequence-dependent thermal (T(m)) and thermodynamic (-DeltaG degrees ) destabilization. The population of B-type conformers derived from eight selected duplexes (i.e. -AG*N- and -CG*N-) was inversely proportional to the -DeltaG degrees and T(m) values, which highlights the importance of carcinogen/base stacking in duplex stabilization even in the face of disrupted Watson-Crick base pairing in S-conformation. CD studies showed that the extent of the adduct-induced negative ellipticities in the 290-350 nm range is correlated linearly with -DeltaG degrees and T(m), but inversely with the population of B-type conformations. Taken together, these results revealed a unique interplay between the extent of carcinogenic interaction with neighboring base pairs and the thermodynamic properties of the AF-modified duplexes. The sequence-dependent S/B heterogeneities have important implications in understanding how arylamine-DNA adducts are recognized in nucleotide excision repair.
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Affiliation(s)
- Srinivasa Rao Meneni
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode IslandKingston, RI 02881, USA
- Department of Chemistry, Loyola UniversityChicago, IL 60626, USA
| | - Rhijuta D'Mello
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode IslandKingston, RI 02881, USA
- Department of Chemistry, Loyola UniversityChicago, IL 60626, USA
| | - Gregory Norigian
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode IslandKingston, RI 02881, USA
- Department of Chemistry, Loyola UniversityChicago, IL 60626, USA
| | - Gregory Baker
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode IslandKingston, RI 02881, USA
- Department of Chemistry, Loyola UniversityChicago, IL 60626, USA
| | - Lan Gao
- Department of Chemistry, Loyola UniversityChicago, IL 60626, USA
| | | | - Bongsup P. Cho
- To whom correspondence should be addressed at Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 41 Lower College Road, Kingston, RI 02881, USA. Tel: +1 401 874 5024; Fax: +1 401 874 5766;
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48
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Vaisman A, Ling H, Woodgate R, Yang W. Fidelity of Dpo4: effect of metal ions, nucleotide selection and pyrophosphorolysis. EMBO J 2005; 24:2957-67. [PMID: 16107880 PMCID: PMC1201362 DOI: 10.1038/sj.emboj.7600786] [Citation(s) in RCA: 159] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2005] [Accepted: 07/22/2005] [Indexed: 11/09/2022] Open
Abstract
We report the crystal structures of a translesion DNA polymerase, Dpo4, complexed with a matched or mismatched incoming nucleotide and with a pyrophosphate product after misincorporation. These structures suggest two mechanisms by which Dpo4 may reject a wrong incoming nucleotide with its preformed and open active site. First, a mismatched replicating base pair leads to poor base stacking and alignment of the metal ions and as a consequence, inhibits incorporation. By replacing Mg2+ with Mn2+, which has a relaxed coordination requirement and tolerates misalignment, the catalytic efficiency of misincorporation increases dramatically. Mn2+ also enhances translesion synthesis by Dpo4. Subtle conformational changes that lead to the proper metal ion coordination may, therefore, be a key step in catalysis. Second, the slow release of pyrophosphate may increase the fidelity of Dpo4 by stalling mispaired primer extension and promoting pyrophosphorolysis that reverses the polymerization reaction. Indeed, Dpo4 has robust pyrophosphorolysis activity and degrades the primer strand in the presence of pyrophosphate. The correct incoming nucleotide allows DNA synthesis to overcome pyrophosphorolysis, but an incorrect incoming nucleotide does not.
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Affiliation(s)
- Alexandra Vaisman
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Hong Ling
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. Tel.: +1 301 402 4645; Fax: +1 301 496 0201; E-mail:
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