1
|
Pujari SS, Jokipii Krueger CC, Chao C, Hutchins S, Hurben AK, Boysen G, Tretyakova N. DEB-FAPy-dG Adducts of 1,3-Butadiene: Synthesis, Structural Characterization, and Formation in 1,2,3,4-Diepoxybutane Treated DNA. Chemistry 2022; 28:e202103245. [PMID: 34767297 PMCID: PMC10603587 DOI: 10.1002/chem.202103245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Indexed: 11/10/2022]
Abstract
Metabolic activation of the human carcinogen 1,3-butadiene (BD) by cytochrome 450 monooxygenases gives rise to a genotoxic diepoxide, 1,2,3,4-diepoxybutane (DEB). This reactive electrophile alkylates guanine bases in DNA to produce N7-(2-hydroxy-3,4-epoxy-1-yl)-dG (N7-DE-dG) adducts. Because of the positive charge at the N7 position of the purine heterocycle, N7-DEB-dG adducts are inherently unstable and can undergo spontaneous depurination or base-catalyzed imidazole ring opening to give N6 -[2-deoxy-D-erythro-pentofuranosyl]-2,6-diamino-3,4-dihydro-4-oxo-5-N-1-(oxiran-2-yl)propan-1-ol-formamidopyrimidine (DEB-FAPy-dG) adducts. Here we report the first synthesis and structural characterization of DEB-FAPy-dG adducts. Authentic standards of DEB-FAPy-dG and its 15 N3 -labeled analogue were used for the development of a quantitative nanoLC-ESI+ -HRMS/MS method, allowing for adduct detection in DEB-treated calf thymus DNA. DEB-FAPy-dG formation in DNA was dependent on DEB concentration and pH, with higher numbers observed under alkaline conditions.
Collapse
Affiliation(s)
- Suresh S Pujari
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Caitlin C Jokipii Krueger
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Christopher Chao
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Spencer Hutchins
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Alexander K Hurben
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Gunnar Boysen
- Department of Environmental and Occupational Health and the Winthrop P Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 West Markham St., Slot 820, Little Rock, AR, 72205, USA
| | - Natalia Tretyakova
- Department of Medicinal Chemistry, College of Pharmacy, Cancer and Cardiovascular Research Building, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| |
Collapse
|
2
|
Effect of N7-methylation on base pairing patterns of guanine: a DFT study. J Mol Model 2021; 27:184. [PMID: 34036469 DOI: 10.1007/s00894-021-04792-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/11/2021] [Indexed: 10/21/2022]
Abstract
In this paper, we aim to determine whether the N7-methylation can influence the base pairing properties of guanine by promoting the formation of guanine enol-tautomers. The keto- to -enol-tautomerization of N7-methylguanine (N7mG) and its base pairing patterns with all the canonical DNA bases have been investigated at the M06-2X/6-311+G(d,p) level of density functional theory. The barrier free energy calculations reveal that N7-methylation does not promote the keto- to enol- tautomerization of guanine. The Watson-Crick-like enol-N7mG:T1 or enol-N7mG:T2 base pair similar to what is observed experimentally is found to be energetically more stable than the keto-N7mG:T base pairs. However, the keto-N7mG:C1 which is structurally similar to the canonical G:C base pair is the most stable base pair among all the base pairs studied here. Thus, our calculations predict that N7mG would pair preferably with cytosine during DNA replication but there is also a probability that it can cause mutation through mispairing with thymine, in agreement with experimental observations.
Collapse
|
3
|
Ullmann R, Becker BV, Rothmiller S, Schmidt A, Thiermann H, Kaatsch HL, Schrock G, Müller J, Jakobi J, Obermair R, Port M, Scherthan H. Genomic Adaption and Mutational Patterns in a HaCaT Subline Resistant to Alkylating Agents and Ionizing Radiation. Int J Mol Sci 2021; 22:ijms22031146. [PMID: 33498964 PMCID: PMC7865644 DOI: 10.3390/ijms22031146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/15/2021] [Accepted: 01/20/2021] [Indexed: 11/16/2022] Open
Abstract
Sulfur mustard (SM) is a chemical warfare agent that can damage DNA via alkylation and oxidative stress. Because of its genotoxicity, SM is cancerogenic and the progenitor of many chemotherapeutics. Previously, we developed an SM-resistant cell line via chronic exposure of the popular keratinocyte cell line HaCaT to increasing doses of SM over a period of 40 months. In this study, we compared the genomic landscape of the SM-resistant cell line HaCaT/SM to its sensitive parental line HaCaT in order to gain insights into genetic changes associated with continuous alkylation and oxidative stress. We established chromosome numbers by cytogenetics, analyzed DNA copy number changes by means of array Comparative Genomic Hybridization (array CGH), employed the genome-wide chromosome conformation capture technique Hi-C to detect chromosomal translocations, and derived mutational signatures by whole-genome sequencing. We observed that chronic SM exposure eliminated the initially prevailing hypotetraploid cell population in favor of a hyperdiploid one, which contrasts with previous observations that link polyploidization to increased tolerance and adaptability toward genotoxic stress. Furthermore, we observed an accumulation of chromosomal translocations, frequently flanked by DNA copy number changes, which indicates a high rate of DNA double-strand breaks and their misrepair. HaCaT/SM-specific single-nucleotide variants showed enrichment of C > A and T > A transversions and a lower rate of deaminated cytosines in the CpG dinucleotide context. Given the frequent use of HaCaT in toxicology, this study provides a valuable data source with respect to the original genotype of HaCaT and the mutational signatures associated with chronic alkylation and oxidative stress.
Collapse
Affiliation(s)
- Reinhard Ullmann
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
- Correspondence:
| | - Benjamin Valentin Becker
- Bundeswehr Central Hospital, Department of Radiology and Neuroradiology, Rübenacherstrasse 170, D-56072 Koblenz, Germany;
| | - Simone Rothmiller
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstr. 11, D-80937 Munich, Germany; (S.R.); (A.S.); (H.T.)
| | - Annette Schmidt
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstr. 11, D-80937 Munich, Germany; (S.R.); (A.S.); (H.T.)
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstr. 11, D-80937 Munich, Germany; (S.R.); (A.S.); (H.T.)
| | - Hanns Leonhard Kaatsch
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Gerrit Schrock
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Jessica Müller
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Julia Jakobi
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Richard Obermair
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Matthias Port
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| | - Harry Scherthan
- Bundeswehr Institute of Radiobiology Affiliated to the University of Ulm, Neuherbergstr. 11, D-80937 Munich, Germany; (H.L.K.); (G.S.); (J.M.); (J.J.); (R.O.); (M.P.); (H.S.)
| |
Collapse
|
4
|
Smith MR, Shock DD, Beard WA, Greenberg MM, Freudenthal BD, Wilson SH. A guardian residue hinders insertion of a Fapy•dGTP analog by modulating the open-closed DNA polymerase transition. Nucleic Acids Res 2019; 47:3197-3207. [PMID: 30649431 PMCID: PMC6451102 DOI: 10.1093/nar/gkz002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 12/17/2018] [Accepted: 01/03/2019] [Indexed: 01/07/2023] Open
Abstract
4,6-Diamino-5-formamidopyrimidine (Fapy•dG) is an abundant form of oxidative DNA damage that is mutagenic and contributes to the pathogenesis of human disease. When Fapy•dG is in its nucleotide triphosphate form, Fapy•dGTP, it is inefficiently cleansed from the nucleotide pool by the responsible enzyme in Escherichia coli MutT and its mammalian homolog MTH1. Therefore, under oxidative stress conditions, Fapy•dGTP could become a pro-mutagenic substrate for insertion into the genome by DNA polymerases. Here, we evaluated insertion kinetics and high-resolution ternary complex crystal structures of a configurationally stable Fapy•dGTP analog, β-C-Fapy•dGTP, with DNA polymerase β. The crystallographic snapshots and kinetic data indicate that binding of β-C-Fapy•dGTP impedes enzyme closure, thus hindering insertion. The structures reveal that an active site residue, Asp276, positions β-C-Fapy•dGTP so that it distorts the geometry of critical catalytic atoms. Removal of this guardian side chain permits enzyme closure and increases the efficiency of β-C-Fapy•dG insertion opposite dC. These results highlight the stringent requirements necessary to achieve a closed DNA polymerase active site poised for efficient nucleotide incorporation and illustrate how DNA polymerase β has evolved to hinder Fapy•dGTP insertion.
Collapse
Affiliation(s)
- Mallory R Smith
- Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center, 3901 Rainbow Blvd Mail Stop #3030, Kansas City, KS 66160, USA
| | - David D Shock
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA
| | - William A Beard
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, and Department of Cancer Biology, University of Kansas Medical Center, 3901 Rainbow Blvd Mail Stop #3030, Kansas City, KS 66160, USA,Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA,To whom correspondence should be addressed. Tel: +1 913 588 5560;
| | - Samuel H Wilson
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, P.O. Box 12233, Research Triangle Park, NC 27709-2233, USA,Correspondence may also be addressed to Samuel H. Wilson. Tel: +1 984 287 3451;
| |
Collapse
|
5
|
Groehler AS, Najjar D, Pujari SS, Sangaraju D, Tretyakova NY. N 6-(2-Deoxy-d- erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5- N-(2-hydroxy-3-buten-1-yl)-formamidopyrimidine Adducts of 1,3-Butadiene: Synthesis, Structural Identification, and Detection in Human Cells. Chem Res Toxicol 2018; 31:885-897. [PMID: 30016111 DOI: 10.1021/acs.chemrestox.8b00123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1,3-Butadiene (BD) is an environmental and occupational toxicant classified as a human carcinogen. BD is metabolically activated by cytochrome P450 monooxygenases to 3,4-epoxy-1-butene (EB), which alkylates DNA to form a range of nucleobase adducts. Among these, the most abundant are the hydrolytically labile N7-guanine adducts such as N7-(2-hydroxy-3-buten-1-yl)-guanine (N7-EB-dG). We now report that N7-EB-dG can be converted to the corresponding ring open N6-(2-deoxy-d- erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5- N-(2-hydroxy-3-buten-1-yl)-formamidopyrimidine (EB-Fapy-dG) adducts. EB-Fapy-dG lesions were detected in EB-treated calf thymus DNA and in EB-treated mammalian cells using quantitative isotope dilution nanoLC-ESI+-MS/MS. EB-Fapy-dG adduct formation in EB-treated calf thymus DNA was concentration dependent and was greatly accelerated at an increased pH. EB-FAPy-dG adduct amounts were 2-fold higher in base excision repair-deficient NEIL1-/- mouse embryonic fibroblasts (MEF) as compared to isogenic controls (NEIL1+/+), suggesting that this lesion may be a substrate for NEIL1. Furthermore, NEIL1-/- cells were sensitized to EB treatment as compared to NEIL1+/+ fibroblasts. Overall, our results indicate that ring-opened EB-FAPy-dG adducts form under physiological conditions, prompting future studies to determine their contributions to genotoxicity and mutagenicity of BD.
Collapse
Affiliation(s)
- Arnold S Groehler
- Department of Medicinal Chemistry and Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Dominic Najjar
- Department of Medicinal Chemistry and Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Suresh S Pujari
- Department of Medicinal Chemistry and Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Dewakar Sangaraju
- Department of Medicinal Chemistry and Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry and Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| |
Collapse
|
6
|
Bamberger SN, Malik CK, Voehler MW, Brown SK, Pan H, Johnson-Salyard TL, Rizzo CJ, Stone MP. Configurational and Conformational Equilibria of N 6-(2-Deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5- N-methylformamidopyrimidine (MeFapy-dG) Lesion in DNA. Chem Res Toxicol 2018; 31:924-935. [PMID: 30169026 DOI: 10.1021/acs.chemrestox.8b00135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The most common lesion in DNA occurring due to clinical treatment with Temozolomide or cellular exposures to other methylating agents is 7-methylguanine (N7-Me-dG). It can undergo a secondary reaction to form N6-(2-deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5- N-methylformamidopyrimidine (MeFapy-dG). MeFapy-dG undergoes epimerization in DNA to produce either α or β deoxyribose anomers. Additionally, conformational rotation around the formyl bond, C5- N5 bond, and glycosidic bond may occur. To characterize and quantitate the mixture of these isomers in DNA, a 13C-MeFapy-dG lesion, in which the CH3 group of the MeFapy-dG was isotopically labeled, was incorporated into the trimer 5'-TXT-3' and the dodecamer 5'-CATXATGACGCT-3' (X = 13C-MeFapy-dG). NMR spectroscopy of both the trimer and dodecamer revealed that the MeFapy-dG lesion exists in single strand DNA as ten configurationally and conformationally discrete species, eight of which may be unequivocally assigned. In the duplex dodecamer, the MeFapy-dG lesion exists as six configurationally and conformationally discrete species. Analyses of NMR data in the single strand trimer confirm that for each deoxyribose anomer, atropisomerism occurs around the C5- N5 bond to produce R a and S a atropisomers. Each atropisomer exhibits geometrical isomerism about the formyl bond yielding E and Z conformations. 1H NMR experiments allow the relative abundances of the species to be determined. For the single strand trimer, the α and β anomers exist in a 3:7 ratio, favoring the β anomer. For the β anomer, with respect to the C5- N5 bond, the R a and S a atropisomers are equally populated. However, the Z geometrical isomer of the formyl moiety is preferred. For the α anomer, the E- S a isomer is present at 12%, whereas all other isomers are present at 5-7%. DNA processing enzymes may differentially recognize different isomers of the MeFapy-dG lesion. Moreover, DNA sequence-specific differences in the populations of configurational and conformational species may modulate biological responses to the MeFapy-dG lesion.
Collapse
Affiliation(s)
- Stephanie N Bamberger
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Chanchal K Malik
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Markus W Voehler
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Summer K Brown
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Hope Pan
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Tracy L Johnson-Salyard
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Carmelo J Rizzo
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Michael P Stone
- Department of Chemistry , Vanderbilt University Center for Structural Biology, Vanderbilt Center in Molecular Toxicology, and the Vanderbilt-Ingram Cancer Center, Vanderbilt University , Nashville , Tennessee 37235 , United States
| |
Collapse
|
7
|
Ramdzan ZM, Ginjala V, Pinder JB, Chung D, Donovan CM, Kaur S, Leduy L, Dellaire G, Ganesan S, Nepveu A. The DNA repair function of CUX1 contributes to radioresistance. Oncotarget 2017; 8:19021-19038. [PMID: 28147323 PMCID: PMC5386666 DOI: 10.18632/oncotarget.14875] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 01/19/2017] [Indexed: 01/19/2023] Open
Abstract
Ionizing radiation generates a broad spectrum of oxidative DNA lesions, including oxidized base products, abasic sites, single-strand breaks and double-strand breaks. The CUX1 protein was recently shown to function as an auxiliary factor that stimulates enzymatic activities of OGG1 through its CUT domains. In the present study, we investigated the requirement for CUX1 and OGG1 in the resistance to radiation. Cancer cell survival following ionizing radiation is reduced by CUX1 knockdown and increased by higher CUX1 expression. However, CUX1 knockdown is sufficient by itself to reduce viability in many cancer cell lines that exhibit high levels of reactive oxygen species (ROS). Consequently, clonogenic results expressed relative to that of non-irradiated cells indicate that CUX1 knockdown confers no or modest radiosensitivity to cancer cells with high ROS. A recombinant protein containing only two CUT domains is sufficient for rapid recruitment to DNA damage, acceleration of DNA repair and increased survival following radiation. In agreement with these findings, OGG1 knockdown and treatment of cells with OGG1 inhibitors sensitize cancer cells to radiation. Together, these results validate CUX1 and more specifically the CUT domains as therapeutic targets.
Collapse
Affiliation(s)
- Zubaidah M Ramdzan
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Vasudeva Ginjala
- Department of Medicine, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey 08903, USA
| | - Jordan B Pinder
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Dudley Chung
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Caroline M Donovan
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Simran Kaur
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Lam Leduy
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Graham Dellaire
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Shridar Ganesan
- Department of Medicine, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey 08903, USA
| | - Alain Nepveu
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Medicine, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Oncology, McGill University, Montreal, Quebec, H3A 1A3, Canada
| |
Collapse
|
8
|
Fleming AM, Burrows CJ. Formation and processing of DNA damage substrates for the hNEIL enzymes. Free Radic Biol Med 2017; 107:35-52. [PMID: 27880870 PMCID: PMC5438787 DOI: 10.1016/j.freeradbiomed.2016.11.030] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/13/2016] [Accepted: 11/16/2016] [Indexed: 12/13/2022]
Abstract
Reactive oxygen species (ROS) are harnessed by the cell for signaling at the same time as being detrimental to cellular components such as DNA. The genome and transcriptome contain instructions that can alter cellular processes when oxidized. The guanine (G) heterocycle in the nucleotide pool, DNA, or RNA is the base most prone to oxidation. The oxidatively-derived products of G consistently observed in high yields from hydroxyl radical, carbonate radical, or singlet oxygen oxidations under conditions modeling the cellular reducing environment are discussed. The major G base oxidation products are 8-oxo-7,8-dihydroguanine (OG), 5-carboxamido-5-formamido-2-iminohydantoin (2Ih), spiroiminodihydantoin (Sp), and 5-guanidinohydantoin (Gh). The yields of these products show dependency on the oxidant and the reaction context that includes nucleoside, single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), and G-quadruplex DNA (G4-DNA) structures. Upon formation of these products in cells, they are recognized by the DNA glycosylases in the base excision repair (BER) pathway. This review focuses on initiation of BER by the mammalian Nei-like1-3 (NEIL1-3) glycosylases for removal of 2Ih, Sp, and Gh. The unique ability of the human NEILs to initiate removal of the hydantoins in ssDNA, bulge-DNA, bubble-DNA, dsDNA, and G4-DNA is outlined. Additionally, when Gh exists in a G4 DNA found in a gene promoter, NEIL-mediated repair is modulated by the plasticity of the G4-DNA structure provided by additional G-runs flanking the sequence. On the basis of these observations and cellular studies from the literature, the interplay between DNA oxidation and BER to alter gene expression is discussed.
Collapse
Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 S 1400 East, Salt Lake City, UT 84112-0850, United States
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 S 1400 East, Salt Lake City, UT 84112-0850, United States.
| |
Collapse
|
9
|
Abstract
DNA nucleobases are the prime targets for chemical modifications by endogenous and exogenous electrophiles. Alkylation of the N7 position of guanine and adenine in DNA triggers base-catalyzed imidazole ring opening and the formation of N5-substituted formamidopyrimidine (N5-R-FAPy) lesions. Me-FAPy-dG adducts induced by exposure to methylating agents and AFB-FAPy-dG lesions formed by aflatoxin B1 have been shown to persist in cells and to contribute to toxicity and mutagenicity. In contrast, the biological outcomes of other N5-substituted FAPy lesions have not been fully elucidated. To enable their structural and biological evaluation, N5-R-FAPy adducts must be site-specifically incorporated into synthetic DNA strands using phosphoramidite building blocks, which can be complicated by their unusual structural complexity. N5-R-FAPy exist as a mixture of rotamers and can undergo isomerization between α, β anomers and furanose-pyranose forms. In this Perspective, we will discuss the main types of N5-R-FAPy adducts and summarize the strategies for their synthesis and structural elucidation. We will also summarize the chemical biology studies conducted with N5-R-FAPy-containing DNA to elucidate their effects on DNA replication and to identify the mechanisms of N5-R-FAPy repair.
Collapse
Affiliation(s)
- Suresh S. Pujari
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Natalia Tretyakova
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
| |
Collapse
|
10
|
Patra A, Banerjee S, Johnson Salyard TL, Malik CK, Christov PP, Rizzo CJ, Stone MP, Egli M. Structural Basis for Error-Free Bypass of the 5-N-Methylformamidopyrimidine-dG Lesion by Human DNA Polymerase η and Sulfolobus solfataricus P2 Polymerase IV. J Am Chem Soc 2015; 137:7011-4. [PMID: 25988947 DOI: 10.1021/jacs.5b02701] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
N(6)-(2-Deoxy-D-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-N-methylformamidopyrimidine (MeFapy-dG) arises from N7-methylation of deoxyguanosine followed by imidazole ring opening. The lesion has been reported to persist in animal tissues. Previous in vitro replication bypass investigations of the MeFapy-dG adduct revealed predominant insertion of C opposite the lesion, dependent on the identity of the DNA polymerase (Pol) and the local sequence context. Here we report crystal structures of ternary Pol·DNA·dNTP complexes between MeFapy-dG-adducted DNA template:primer duplexes and the Y-family polymerases human Pol η and P2 Pol IV (Dpo4) from Sulfolobus solfataricus. The structures of the hPol η and Dpo4 complexes at the insertion and extension stages, respectively, are representative of error-free replication, with MeFapy-dG in the anti conformation and forming Watson-Crick pairs with dCTP or dC.
Collapse
Affiliation(s)
- Amritraj Patra
- †Department of Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Surajit Banerjee
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States.,§Northeastern Collaborative Access Team and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Building 436E, Argonne, Illinois 60439, United States
| | - Tracy L Johnson Salyard
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Chanchal K Malik
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Plamen P Christov
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Carmelo J Rizzo
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Michael P Stone
- ‡Department of Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Martin Egli
- †Department of Biochemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt Institute of Chemical Biology, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| |
Collapse
|
11
|
Minko IG, Earley LF, Larlee KE, Lin YC, Lloyd RS. Pyrosequencing: applicability for studying DNA damage-induced mutagenesis. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2014; 55:601-608. [PMID: 24962778 PMCID: PMC4197070 DOI: 10.1002/em.21882] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 05/15/2014] [Indexed: 06/03/2023]
Abstract
Site-specifically modified DNAs are routinely used in the study of DNA damage-induced mutagenesis. These analyses involve the creation of DNA vectors containing a lesion at a pre-determined position, DNA replication, and detection of mutations at the target site. The final step has previously required the isolation of individual DNA clones, hybridization with radioactively labeled probes, and verification of mutations by Sanger sequencing. In the search for an alternative procedure that would allow direct quantification of sequence variants in a mixed population of DNA molecules, we evaluated the applicability of pyrosequencing to site-specific mutagenesis assays. The progeny DNAs were analyzed that originated from replication of N(6) -(deoxy-D-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-N-methylformamidopyrimidine (MeFapy-dG)-containing vectors in primate cells, with the lesion being positioned in the 5'-GCNGG-3' sequence context. Pyrosequencing detected ∼8% G to T transversions and ∼3.5% G to A transitions, a result that was in excellent agreement with frequencies previously measured by the standard procedure (Earley LF et al. [2013]: Chem Res Toxicol 26:1108-1114). However, ∼3.5% G to C transversions and ∼2.0% deletions could not be detected by pyrosequencing. Consistent with these observations, the sensitivity of pyrosequencing for measuring the single deoxynucleotide variants differed depending on the deoxynucleotide identity, and in the given sequence contexts, was determined to be ∼1-2% for A and T and ∼5% for C. Pyrosequencing of other DNA isolates that were obtained following replication of MeFapy-dG-containing vectors in primate cells or Escherichia coli, identified several additional limitations. Collectively, our data demonstrated that pyrosequencing can be used for studying DNA damage-induced mutagenesis as an effective complementary experimental approach to current protocols.
Collapse
Affiliation(s)
- Irina G. Minko
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, USA
| | - Lauriel F. Earley
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, USA
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Kimberly E. Larlee
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ying-Chih Lin
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, USA
- Cancer Biology Program, Oregon Health & Science University, Portland, OR 97239, USA
| | - R. Stephen Lloyd
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR 97239, USA
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| |
Collapse
|
12
|
Philippin G, Cadet J, Gasparutto D, Mazon G, Fuchs RP. Ethylene oxide and propylene oxide derived N7-alkylguanine adducts are bypassed accurately in vivo. DNA Repair (Amst) 2014; 22:133-6. [PMID: 25173234 DOI: 10.1016/j.dnarep.2014.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 08/01/2014] [Accepted: 08/04/2014] [Indexed: 01/09/2023]
Abstract
Adducts formed at the nucleophilic N7 position of guanine are the most abundant lesions produced by alkylating agents such as ethylene oxide (EO) and propylene oxide (PO). In order to investigate the intrinsic mutagenic potential of N7-alkylguanine adducts, we prepared single-stranded DNA probes containing a single well-defined N7-alkylguanine adduct under conditions that minimize the presence of depurinated molecules. Following introduction of these probes into Escherichia coli cells, the effect of the N7-alkylguanine adducts on the efficiency and fidelity of replication was determined. To investigate the effect on replication we monitored the relative transformation efficiency of the lesion containing constructs with respect to the control construct. The methyl adduct was found not to be toxic, while the N7-(2-hydroxyethyl)guanine (N7-heG) and N7-(2-hydroxypropyl)guanine (N7-hpG) adducts reduce the transformation efficiency to ≈70% and 40%, respectively. Within the detection limits of our assay, replication across the N7-alkylguanine adducts in vivo is essentially error-free, as no mutant colony was observed among ≈300 individual sequenced colonies (i.e., mutation frequency<0.3%).
Collapse
Affiliation(s)
- Gaëlle Philippin
- Cancer Research Center of Marseille, CNRS, UMR7258 Genome Instability and Carcinogenesis (equipe labellisée Ligue Contre le Cancer) Inserm, U1068, Paoli-Calmettes Institute, Aix-Marseille Univ, F-13009 Marseille, France
| | - Jean Cadet
- Lésions des Acides Nucléiques, INAC/SCIB - UMR-E3 CEA/UJF, CEA Grenoble 17 avenue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - Didier Gasparutto
- Lésions des Acides Nucléiques, INAC/SCIB - UMR-E3 CEA/UJF, CEA Grenoble 17 avenue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - Gerard Mazon
- Cancer Research Center of Marseille, CNRS, UMR7258 Genome Instability and Carcinogenesis (equipe labellisée Ligue Contre le Cancer) Inserm, U1068, Paoli-Calmettes Institute, Aix-Marseille Univ, F-13009 Marseille, France
| | - Robert P Fuchs
- Cancer Research Center of Marseille, CNRS, UMR7258 Genome Instability and Carcinogenesis (equipe labellisée Ligue Contre le Cancer) Inserm, U1068, Paoli-Calmettes Institute, Aix-Marseille Univ, F-13009 Marseille, France.
| |
Collapse
|
13
|
Sinha BK, Leinisch F, Bhattacharjee S, Mason RP. DNA cleavage and detection of DNA radicals formed from hydralazine and copper (II) by ESR and immuno-spin trapping. Chem Res Toxicol 2014; 27:674-82. [PMID: 24502259 DOI: 10.1021/tx500011m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Metal ion-catalyzed oxidation of hydrazine and its derivatives leads to the formation of the hydrazyl radical and subsequently to oxy-radicals in the presence of molecular oxygen. Here, we have examined the role of Cu(2+)-catalyzed oxidation of hydralazine in the induction of DNA damage. Neither 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) nor dimethyl sulfoxide (DMSO) was effective in inhibiting hydralazine-Cu(2+)-induced DNA damage. Singlet oxygen did not appear to participate in this DNA cleavage. The one-electron oxidation of hydralazine also leads to the formation of DNA radicals as confirmed by immuno-spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide. Electron spin resonance (ESR) and spin-trapping studies further confirmed the formation of DNA radicals; predominantly, 2'-deoxyadenosine radical adducts were detected, while some radicals were also detected with other nucleosides. Our results suggest that free hydroxyl radicals may not be the main damaging species causing DNA cleavage and that possibly Cu-peroxide complexes, formed from Cu(+)-H2O2, are responsible for this hydralazine-Cu(2+)-induced DNA cleavage.
Collapse
Affiliation(s)
- Birandra K Sinha
- Laboratory of Toxicology and Pharmacology, National Institutes of Environmental Health Sciences , Research Triangle Park, North Carolina, United States
| | | | | | | |
Collapse
|
14
|
Mandal S, Poria DK, Seth DK, Ray PS, Gupta P. Cyclometalated rhodium and iridium complexes with imidazole containing Schiff bases: Synthesis, structure and cellular imaging. Polyhedron 2014; 73:12-21. [PMID: 31274947 DOI: 10.1016/j.poly.2014.01.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cyclometalated rhodium(III) and iridium(III) complexes (1-4) of two Schiff base ligands L1 and L2 with the general formula [M(ppy)2(Ln)]Cl {M = Rh, Ir; ppy = 2-phenylpyridine; n = 1, 2; L = Schiff base ligand} have been synthesized. The new ligands and the complexes have been characterized with spectroscopic techniques. Electrochemistry of the complexes revealed anodic behavior, corresponding to an M(III) to M(IV) oxidation. The X-ray crystal structures of complexes 2 and 4 have also been determined to interpret the coordination behavior of the complexes. Photophysical study shows that all the complexes display fluorescence at room temperature with quantum yield of about 3 × 10-2 to 5 × 10-2. The electronic absorption spectra of all the complexes fit well with the computational studies. Cellular imaging studies were done with the newly synthesized complexes. To the best of our knowledge, this is the first report of organometallic complexes of rhodium(III) and iridium(III) with Schiff base ligands explored for cellular imaging. Emphasis of this work lies on the structural features, photophysical behavior, cellular uptake and imaging of the fluorescent transition metal complexes.
Collapse
Affiliation(s)
- Soumik Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur campus, Mohanpur, Nadia 741252, West Bengal, India
| | - Dipak K Poria
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, Mohanpur, Nadia 741252, West Bengal, India
| | - Dipravath K Seth
- Department of Chemistry, Inorganic Chemistry Section, Jadavpur University, Jadavpur 700032, India
| | - Partho Sarothi Ray
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur Campus, Mohanpur, Nadia 741252, West Bengal, India
| | - Parna Gupta
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur campus, Mohanpur, Nadia 741252, West Bengal, India
| |
Collapse
|
15
|
Acharyya N, Chattopadhyay S, Maiti S. Chemoprevention against arsenic-induced mutagenic DNA breakage and apoptotic liver damage in rat via antioxidant and SOD1 upregulation by green tea (Camellia sinensis) which recovers broken DNA resulted from arsenic-H2O2 related in vitro oxidant stress. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2014; 32:338-361. [PMID: 25436473 DOI: 10.1080/10590501.2014.967061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Green tea (Camellia sinensis; CS) strongly reverses/prevents arsenic-induced apoptotic hepatic degeneration/micronecrosis and mutagenic DNA damage in in vitro oxidant stress model and in rat as shown by comet assay and histoarchitecture (HE and PAS staining) results. Earlier, we demonstrated a link between carcinogenesis and impaired antioxidant system-associated mutagenic DNA damage in arsenic-exposed human. In this study, arsenic-induced (0.6 ppm/100 g body weight/day for 28 days) impairment of cytosolic superoxide-dismutase (SOD1), catalase, xanthine-oxidase, thiol, and urate activities/levels led to increase in tissue levels of damaging malondialdehyde, conjugated dienes, serum necrotic-marker lactate-dehydrogenase, and metabolic inflammatory-marker c-reactive protein suggesting dysregulation at the transcriptional/signal-transduction level. These are decisively restrained by CS-extract (≥10 mg/ml aqueous) with a restoration of DNA/tissue structure. The structural/functional impairment of dialyzed and centrifugally concentrated (6-8 kd cutoff) hepatic SOD1 via its important Cys modifications by H2O2/arsenite redox-stress and that protection by CS/2-mercaptoethanol are shown in in vitro/in situ studies paralleling the present Swiss-Model-generated rSOD1 structural data. Here, arsenite(3+) incubation (≥10(-8) μM + 10 mM H2O2, 2 hr) is shown for the first time with this low-concentration to initiate breakage in rat hepatic-DNA in vitro whereas, arsenite/H2O2/UV-radiation does not affect DNA separately. Arsenic initiates Fe and Cu ion-associated free-radical reaction cascade in vivo. Here, 10 μM of Cu(2+)/Fe(3+)/As(3+) +H2O2-induced in vitro DNA fragmentation is prevented by CS (≥1 mg/ml), greater than the prevention of ascorbate or tocopherol or DMSO or their combination. Moreover, CS incubation for various time with differentially and already degraded DNA resulted from pre-incubation in 10 μM As(3+)-H2O2 system markedly recovers broken DNA. Present results decisively suggest for the first time that CS and its mixed polyphenols have potent SOD1 protecting, diverse radical-scavenging and antimutagenic activities furthering to DNA protection/therapy in arsenic-induced tissue necrosis/apoptosis.
Collapse
Affiliation(s)
- Nirmallya Acharyya
- a Post Graduate Department of Biochemistry and Biotechnology, Cell and Molecular Therapeutics Laboratory , Oriental Institute of Science and Technology, Vidyasagar University , Midnapore , West Bengal , India
| | | | | |
Collapse
|
16
|
Earley LF, Minko IG, Christov PP, Rizzo CJ, Lloyd RS. Mutagenic spectra arising from replication bypass of the 2,6-diamino-4-hydroxy-N(5)-methyl formamidopyrimidine adduct in primate cells. Chem Res Toxicol 2013; 26:1108-14. [PMID: 23763662 DOI: 10.1021/tx4001495] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA exposures to electrophilic methylating agents that are commonly used during chemotherapeutic treatments cause diverse chemical modifications of nucleobases, with reaction at N7-dG being the most abundant. Although this base modification frequently results in destabilization of the glycosyl bond and spontaneous depurination, the adduct can react with hydroxide ion to yield a stable, ring-opened MeFapy-dG, and this lesion has been reported to persist in animal tissues. Results from prior in vitro replication bypass investigations of the MeFapy-dG adduct had revealed complex spectra of replication errors that differed depending on the identity of DNA polymerase and the local sequence context. In this study, a series of nine site-specifically modified MeFapy-dG-containing oligodeoxynucleotides were engineered into a shuttle vector and subjected to replication in primate cells. In all nine sequence contexts examined, MeFapy-dG was shown to be associated with a strong mutator phenotype, predominantly causing base substitutions, with G to T transversions being most common. Single and dinucleotide deletions were also found in a subset of the sequence contexts. Interestingly, single-nucleotide deletions occurred at not only the adducted site, but also one nucleotide downstream of the adduct. Standard models for primer-template misalignment could account for some but not all mutations observed. These data demonstrate that in addition to mutagenesis predicted from replication of DNAs containing O(6)-Me-dG and O(4)-Me-dT, the MeFapy-dG adduct likely contributes to mutagenic events following chemotherapeutic treatments.
Collapse
Affiliation(s)
- Lauriel F Earley
- Center for Research on Occupational and Environmental Toxicology and §Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239, United States
| | | | | | | | | |
Collapse
|
17
|
Joyner-Matos J, Hicks KA, Cousins D, Keller M, Denver DR, Baer CF, Estes S. Evolution of a higher intracellular oxidizing environment in Caenorhabditis elegans under relaxed selection. PLoS One 2013; 8:e65604. [PMID: 23776511 PMCID: PMC3679170 DOI: 10.1371/journal.pone.0065604] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/29/2013] [Indexed: 01/22/2023] Open
Abstract
We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutation-accumulation (MA) lines of the nematode Caenorhabditis elegans and in their common ancestor. We measured steady-state levels of free radicals and oxidatively damaged guanosine nucleosides in the somatic tissues of five MA lines for which nuclear genome base substitution and GC-TA transversion frequencies are known. The two markers of oxidative stress are highly correlated and are elevated in the MA lines relative to the ancestor; point estimates of the per-generation rate of mutational decay (ΔM) of these measures of oxidative stress are similar to those reported for fitness-related traits. Conversely, there is no significant relationship between either marker of oxidative stress and the per-generation frequencies of base substitution or GC-TA transversion. Although these results provide no direct evidence for a causative relationship between oxidative damage and base substitution mutations, to the extent that oxidative damage may be weakly mutagenic in the germline, the case for condition-dependent mutation is advanced.
Collapse
Affiliation(s)
- Joanna Joyner-Matos
- Department of Biology, Eastern Washington University, Cheney, Washington, United States of America.
| | | | | | | | | | | | | |
Collapse
|
18
|
Rapid inactivation and proteasome-mediated degradation of OGG1 contribute to the synergistic effect of hyperthermia on genotoxic treatments. DNA Repair (Amst) 2013; 12:227-37. [PMID: 23332971 DOI: 10.1016/j.dnarep.2012.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/18/2012] [Accepted: 12/21/2012] [Indexed: 12/16/2022]
Abstract
Inhibition of DNA repair has been proposed as a mechanism underlying heat-induced sensitization of tumour cells to some anticancer treatments. Base excision repair (BER) constitutes the main pathway for the repair of DNA lesions induced by oxidizing or alkylating agents. Here, we report that mild hyperthermia, without toxic consequences per se, affects cellular DNA glycosylase activities, thus impairing BER. Exposure of cells to mild hyperthermia leads to a rapid and selective inactivation of OGG1 (8-oxoguanine DNA glycosylase) associated with the relocalisation of the protein into a detergent-resistant cellular fraction. Following its inactivation, OGG1 is ubiquitinated and directed to proteasome-mediated degradation, through a CHIP (C-terminus of HSC70-interacting protein) E3 ligase-mediated process. Moreover, the residual OGG1 accumulates in the perinuclear region leading to further depletion from the nucleus. As a consequence, HeLa cells subjected to hyperthermia and exposed to a genotoxic treatment have a reduced capacity to repair OGG1 cognate base lesions and an enhanced cell growth defect. The partial alleviation of this response by OGG1 overexpression indicates that heat-induced glycosylase inactivation contributes to the synergistic effect of hyperthermia on genotoxic treatments. Taken together, our results suggest that OGG1 inhibition contributes to heat-induced chemosensitisation of cells and could lay the basis for new anticancer therapeutic protocols that include hyperthermia.
Collapse
|
19
|
Brooks SC, Adhikary S, Rubinson EH, Eichman BF. Recent advances in the structural mechanisms of DNA glycosylases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:247-71. [PMID: 23076011 DOI: 10.1016/j.bbapap.2012.10.005] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/24/2012] [Accepted: 10/05/2012] [Indexed: 02/06/2023]
Abstract
DNA glycosylases safeguard the genome by locating and excising a diverse array of aberrant nucleobases created from oxidation, alkylation, and deamination of DNA. Since the discovery 28years ago that these enzymes employ a base flipping mechanism to trap their substrates, six different protein architectures have been identified to perform the same basic task. Work over the past several years has unraveled details for how the various DNA glycosylases survey DNA, detect damage within the duplex, select for the correct modification, and catalyze base excision. Here, we provide a broad overview of these latest advances in glycosylase mechanisms gleaned from structural enzymology, highlighting features common to all glycosylases as well as key differences that define their particular substrate specificities.
Collapse
Affiliation(s)
- Sonja C Brooks
- Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | | | | | | |
Collapse
|
20
|
Christov PP, Yamanaka K, Choi JY, Takata KI, Wood RD, Guengerich FP, Lloyd RS, Rizzo CJ. Replication of the 2,6-diamino-4-hydroxy-N(5)-(methyl)-formamidopyrimidine (MeFapy-dGuo) adduct by eukaryotic DNA polymerases. Chem Res Toxicol 2012; 25:1652-61. [PMID: 22721435 DOI: 10.1021/tx300113e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
N(6)-(2-Deoxy-d-erythro-pentofuranosyl)-2,6-diamino-3,4-dihydro-4-oxo-5-N-methylformamidopyrimidine (MeFapy-dGuo) has been identified as a stable DNA adduct that arises from the reaction of DNA with a variety of methylating agents. Since this lesion persists in DNA and may contribute to the overall mutagenesis from electrophilic methylating agents, the MeFapy-dGuo lesion was incorporated into oligonucleotides, and its replication bypass was examined in vitro with a panel of eukaryotic high fidelity (hPols α, β, and δ/PCNA) and translesion (hPols η, κ, ι, Rev1, ν, and yPol ζ) polymerases to address its miscoding potential. The MeFapy-dGuo was found to be a strong block to the high fidelity polymerases at either the insertion or the extension step. Efficient translesion synthesis was observed for hPols η and κ, and the combined activities of hRev1 and yPol ζ. The nucleotide sequences of the extension products were determined by mass spectrometry. The error-free extension product was the most abundant product observed for each polymerase. Misreplication products, which included misinsertion of Thy, Gua, and Ade opposite the MeFapy-dGuo lesion, as well as an interesting one-nucleotide deletion product, were observed when hPols η and κ were employed; these events accounted for 8-29% of the total extension products observed. The distribution and abundance of the misreplication products were dependent on the polymerases and local sequence context of the lesion. Collectively, these data suggest that although MeFapy-dGuo adducts represent a relatively minor proportion of the total alkylated lesions, their miscoding potentials could significantly contribute to genomic instability.
Collapse
Affiliation(s)
- Plamen P Christov
- Departments of Chemistry and Biochemistry, Vanderbilt-Ingram Cancer Center and Center in Molecular Toxicology, Vanderbilt University, Nashville, TN 37235, USA
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Jena NR, Mishra PC. Formation of ring-opened and rearranged products of guanine: mechanisms and biological significance. Free Radic Biol Med 2012; 53:81-94. [PMID: 22583701 DOI: 10.1016/j.freeradbiomed.2012.04.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 03/30/2012] [Accepted: 04/06/2012] [Indexed: 11/16/2022]
Abstract
DNA damage by endogenous and exogenous agents is a serious concern, as the damaged products can affect genome integrity severely. Damage to DNA may arise from various factors such as DNA base modifications, strand break, inter- and intrastrand crosslinks, and DNA-protein crosslinks. Among these factors, DNA base modification is a common and important form of DNA damage that has been implicated in mutagenesis, carcinogenesis, and many other pathological conditions. Among the four DNA bases, guanine (G) has the smallest oxidation potential, because of which it is frequently modified by reactive species, giving rise to a plethora of lethal lesions. Similarly, 8-oxo-7,8-dihydroguanine (8-oxoG), an oxidatively damaged guanine lesion, also undergoes various degradation reactions giving rise to several mutagenic species. The various products formed from reactions of G or 8-oxoG with different reactive species are mainly 2,6-diamino-4-oxo-5-formamidopyrimidine, 2,5-diamino-4H-imidazolone, 2,2,4-triamino-5-(2H)-oxazolone, 5-guanidino-4-nitroimidazole, guanidinohydantoin, spiroiminodihydantoin, cyanuric acid, parabanic acid, oxaluric acid, and urea, among others. These products are formed from either ring opening or ring opening and subsequent rearrangement. The main aim of this review is to provide a comprehensive overview of various possible reactions and the mechanisms involved, after which these ring-opened and rearranged products of guanine would be formed in DNA. The biological significance of oxidatively damaged products of G is also discussed.
Collapse
Affiliation(s)
- N R Jena
- Department of Physics, Indian Institute of Information Technology, Design and Manufacturing, Khamaria, Jabalpur 482005, India.
| | | |
Collapse
|
22
|
|
23
|
Greenberg MM. The formamidopyrimidines: purine lesions formed in competition with 8-oxopurines from oxidative stress. Acc Chem Res 2012; 45:588-97. [PMID: 22077696 DOI: 10.1021/ar2002182] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA is constantly exposed to agents that induce structural damage, from sources both internal and external to an organism. Endogenous species, such as oxidizing chemicals, and exogenous agents, such as ultraviolet rays in sunlight, together produce more than 70 distinct chemical modifications of native nucleotides. Of these, about 15 of the lesions have been detected in cellular DNA. This kind of structural DNA damage can be cytotoxic, carcinogenic, or both and is being linked to an increasingly lengthy list of diseases. The formamidopyrimidine (Fapy) lesions are a family of DNA lesions that result after purines undergo oxidative stress. The Fapy lesions are produced in yields comparable to the 8-oxopurines, which, owing in part to a perception of mutagenicity in some quarters, have been subjected to intense research scrutiny. But despite the comparable abundance of the formamidopyrimidines and the 8-oxopurines, until recently very little was known about the effects of Fapy lesions on biochemical processes involving DNA or on the structure and stability of the genomic material. In this Account, we discuss the detection of Fapy lesions in DNA and the mechanism proposed for their formation. We also describe methods for the chemical synthesis of oligonucleotides containing Fapy·dA or Fapy·dG and the outcomes of chemical and biochemical studies utilizing these compounds. These experiments reveal that the formamidopyrimidines decrease the fidelity of polymerases and are substrates for DNA repair enzymes. The mutation frequency of Fapy·dG in mammals is even greater than that of 8-oxodGuo (8-oxo-7,8-dihydro-2'-deoxyguanosine, one of the 8-oxopurines), suggesting that this lesion could be a useful biomarker and biologically significant. Despite clear similarities, the formamidopyrimidines have lived in the shadow of the corresponding 8-oxopurine lesions. But the recent development of methods for synthesizing oligonucleotides containing Fapy·dA or Fapy·dG has accelerated research on these lesions, revealing that the formamidopyrimidines are repaired as efficiently and, in some cases, more rapidly than the 8-oxopurines. Fapy·dG appears to be a lesion of biochemical consequence, and further study of its mutagenicity, repair, and interactions with DNA structure will better define the cellular details involving this important product of DNA stress.
Collapse
Affiliation(s)
- Marc M. Greenberg
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
| |
Collapse
|
24
|
Kanamitsu K, Ikeda S. Fission yeast homologs of human XPC and CSB, rhp41 and rhp26, are involved in transcription-coupled repair of methyl methanesulfonate-induced DNA damage. Genes Genet Syst 2011; 86:83-91. [PMID: 21670547 DOI: 10.1266/ggs.86.83] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Methyl methanesulfonate (MMS) methylates nitrogen atoms in purines, and predominantly produces 7-methylguanine and 3-methyladenine (3-meA). Previously, we showed that base excision repair (BER) and nucleotide excision repair (NER) synergistically function to repair MMS-induced DNA damage in the fission yeast Schizosaccharomyces pombe. Here, we studied the roles of NER components in repair of 3-meA and BER intermediates such as the AP site and single strand breaks. Mutants of rhp41 (XPC homolog) and rhp26 (CSB homolog) exhibited moderate sensitivity to MMS. Transcription of the fbp1 gene, which is induced by glucose starvation, was strongly inhibited by MMS damage in rhp41Δ and rhp26Δ strains but not in wild type and 3-meA DNA glycosylase-deficient cells. The results indicate that Rhp41p and Rhp26p are involved in transcription-coupled repair (TCR) of MMS-induced DNA damage. In the BER pathway of S. pombe, AP lyase activity of Nth1p mainly incises the AP site to generate a 3'-blocked end, which is in turn converted to 3'-OH by Apn2p. Deletion of rad16 or rhp26 in the nth1Δ strain greatly enhanced MMS sensitivity, suggesting that the AP site could also be corrected by TCR. Double mutant apn2Δ/rad16Δ exhibited hypersensitivity to MMS, implying that Rad16p provides a backup pathway for removal of the 3'-blocked end. Moreover, an rhp51Δ strain was extremely sensitive to MMS and double mutants of nth1Δ/rhp51Δ and apn2Δ/rhp51Δ increased the sensitivity, suggesting that homologous recombination is necessary for repair of three different types of lesions, 3-meA, AP sites and 3'-blocked ends.
Collapse
Affiliation(s)
- Kyoichiro Kanamitsu
- Department of Biochemistry, Faculty of Science, Okayama University of Science, Okayama 700-0005, Japan
| | | |
Collapse
|
25
|
Shanmugasundaram M, Puranik M. Vibrational markers of structural distortion in adenine nucleobases upon DNA damage. Phys Chem Chem Phys 2011; 13:3851-62. [DOI: 10.1039/c0cp01731k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
26
|
Kim S, Schaefer HF. Vertical detachment energies of anionic thymidine: Microhydration effects. J Chem Phys 2010; 133:144305. [DOI: 10.1063/1.3488105] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
27
|
Christov PP, Banerjee S, Stone MP, Rizzo CJ. Selective Incision of the alpha-N-Methyl-Formamidopyrimidine Anomer by Escherichia coli Endonuclease IV. J Nucleic Acids 2010; 2010. [PMID: 20798848 PMCID: PMC2925382 DOI: 10.4061/2010/850234] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 06/04/2010] [Indexed: 01/09/2023] Open
Abstract
Formamidopyrimidines (Fapy) lesions result from ring opening of the imidazole portion of purines. Fapy lesions can isomerize from the natural β-anomeric stereochemistry to the α-configuration. We have unambiguously demonstrated that the α-methyl-Fapy-dG (MeFapy-dG) lesion is a substrate for Escherichia coli Endonuclease IV (Endo IV). Treatment of a MeFapy-dG-containing 24 mer duplex with Endo IV resulted in 36–40% incision. The catalytic efficiency of the incision was comparable to that of α-dG in the same duplex sequence. The α- and β-MeFapy-dG anomers equilibrate to ~21 : 79 ratio over ~3 days. Related studies with a duplex containing the α-Fapy-dG lesion derived from aflatoxin B1 epoxide (α-AFB-Fapy-dG) showed only low levels of incision. It is hypothesized that the steric bulk of the aflatoxin moiety interferes with the binding of the substrate to Endo IV and the incision chemistry.
Collapse
Affiliation(s)
- Plamen P Christov
- Departments of Chemistry and Biochemistry, Center in Molecular Toxicology, Vanderbilt University, VU Station B 351822, Nashville, N 37235-1822, USA
| | | | | | | |
Collapse
|
28
|
Sipinen V, Laubenthal J, Baumgartner A, Cemeli E, Linschooten JO, Godschalk RWL, Van Schooten FJ, Anderson D, Brunborg G. In vitro evaluation of baseline and induced DNA damage in human sperm exposed to benzo[a]pyrene or its metabolite benzo[a]pyrene-7,8-diol-9,10-epoxide, using the comet assay. Mutagenesis 2010; 25:417-25. [PMID: 20488941 PMCID: PMC2893308 DOI: 10.1093/mutage/geq024] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Exposure to genotoxins may compromise DNA integrity in male reproductive cells, putting future progeny at risk for developmental defects and diseases. To study the usefulness of sperm DNA damage as a biomarker for genotoxic exposure, we have investigated cellular and molecular changes induced by benzo[a]pyrene (B[a]P) in human sperm in vitro, and results have been compared for smokers and non-smokers. Sperm DNA obtained from five smokers was indeed more fragmented than sperm of six non-smokers (mean % Tail DNA 26.5 and 48.8, respectively), as assessed by the alkaline comet assay (P < 0.05). B[a]P-related DNA adducts were detected at increased levels in smokers as determined by immunostaining. Direct exposure of mature sperm cells to B[a]P (10 or 25 μM) caused moderate increases in DNA fragmentation which was independent of addition of human liver S9 mix for enzymatic activation of B[a]P, suggesting some unknown metabolism of B[a]P in ejaculates. In vitro exposure of samples to various doses of B[a]P (with or without S9) did not reveal any significant differences in sensitivity to DNA fragmentation between smokers and non-smokers. Incubations with the proximate metabolite benzo[a]pyrene-r-7,t-8-dihydrodiol-t9,10-epoxide (BPDE) produced DNA fragmentation in a dose-dependent manner (20 or 50 μM), but only when formamidopyrimidine DNA glycosylase treatment was included in the comet assay. These levels of DNA fragmentation were, however, low in relation to very high amounts of BPDE–DNA adducts as measured with 32P postlabelling. We conclude that sperm DNA damage may be useful as a biomarker of direct exposure of sperm using the comet assay adapted to sperm, and as such the method may be applicable to cohort studies. Although the sensitivity is relatively low, DNA damage induced in earlier stages of spermatogenesis may be detected with higher efficiencies.
Collapse
Affiliation(s)
- V Sipinen
- Department of Chemical Toxicology, Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Mechanisms of hop inhibition include the transmembrane redox reaction. Appl Environ Microbiol 2009; 76:142-9. [PMID: 19880646 DOI: 10.1128/aem.01693-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In this work, a novel mechanistic model of hop inhibition beyond the proton ionophore action toward (beer spoiling) bacteria was developed. Investigations were performed with model systems using cyclic voltammetry for the determination of redox processes/conditions in connection with growth challenges with hop-sensitive and -resistant Lactobacillus brevis strains in the presence of oxidants. Cyclic voltammetry identified a transmembrane redox reaction of hop compounds at low pH (common in beer) and in the presence of manganese (present in millimolar levels in lactic acid bacteria). The antibacterial action of hop compounds could be extended from the described proton ionophore activity, lowering the intracellular pH, to pronounced redox reactivity, causing cellular oxidative damage. Accordingly, a correlation between the resistance of L. brevis strains to a sole oxidant to their resistance to hop could not be expected and was not detected. However, in connection with our recent study concerning hop ionophore properties and the resistance of hop-sensitive and -tolerant L. brevis strains toward proton ionophores (J. Behr and R. F. Vogel, J. Agric. Food Chem. 57:6074-6081, 2009), we suggest that both ionophore and oxidant resistance are required for survival under hop stress conditions and confirmed this correlation according to the novel mechanistic model. In consequence, the expression of several published hop resistance mechanisms involved in manganese binding/transport and intracellular redox balance, as well as that of proteins involved in oxidative stress under "highly reducing" conditions (cf. anaerobic cultivation and "antioxidative" hop compounds in the growth medium), is now comprehensible. Accordingly, hop resistance as a multifactorial dynamic property at least implies distinct resistance levels against two different mechanisms of hop inhibition, namely, proton ionophore-induced and oxidative stress-induced mechanisms. Beyond this specific model of hop inhibition, these investigations provide general insight on the role of electrophysiology and ion homeostasis in bacterial stress responses to membrane-active drugs.
Collapse
|
30
|
Shrivastav N, Li D, Essigmann JM. Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation. Carcinogenesis 2009; 31:59-70. [PMID: 19875697 DOI: 10.1093/carcin/bgp262] [Citation(s) in RCA: 207] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The reaction of DNA-damaging agents with the genome results in a plethora of lesions, commonly referred to as adducts. Adducts may cause DNA to mutate, they may represent the chemical precursors of lethal events and they can disrupt expression of genes. Determination of which adduct is responsible for each of these biological endpoints is difficult, but this task has been accomplished for some carcinogenic DNA-damaging agents. Here, we describe the respective contributions of specific DNA lesions to the biological effects of low molecular weight alkylating agents.
Collapse
Affiliation(s)
- Nidhi Shrivastav
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | |
Collapse
|
31
|
Im EK, Hong CH, Back JH, Han YS, Chung JH. Functional identification of an 8-oxoguanine specific endonuclease from Thermotoga maritima. BMB Rep 2009; 38:676-82. [PMID: 16336782 DOI: 10.5483/bmbrep.2005.38.6.676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To date, no 8-oxoguanine-specific endonuclease-coding gene has been identified in Thermotoga maritima of the order Thermotogales, although its entire genome has been deciphered. However, the hypothetical protein Tm1821 from T. maritima, has a helix-hairpin-helix motif that is considered to be important for DNA binding and catalytic activity. Here, Tm1821 was overexpressed in Escherichia coli and purified using Ni-NTA affinity chromatography, protease digestion, and gel filtration. Tm1821 protein was found to efficiently cleave an oligonucleotide duplex containing 8-oxoguanine, but Tm1821 had little effect on other substrates containing modified bases. Moreover, Tm1821 strongly preferred DNA duplexes containing an 8-oxoguanine:C pair among oligonucleotide duplexes containing 8-oxoguanine paired with four different bases (A, C, G, or T). Furthermore, Tm1821 showed AP lyase activity and Schiff base formation with 8-oxoguanine in the presence of NaBH4, which suggests that it is a bifunctional DNA glycosylase. Tm1821 protein shares unique conserved amino acids and substrate specificity with an 8-oxoguanine DNA glycosylase from the hyperthermophilic archaeon. Thus, the DNA recognition and catalytic mechanisms of Tm1821 protein are likely to be similar to archaeal repair protein, although T. maritima is an eubacterium.
Collapse
Affiliation(s)
- Eun Kyoung Im
- Yonsei Research Institute of Aging Science, Yonsei University, Seoul 120-749, Korea
| | | | | | | | | |
Collapse
|
32
|
Pachkowski BF, Tano K, Afonin V, Elder RH, Takeda S, Watanabe M, Swenberg JA, Nakamura J. Cells deficient in PARP-1 show an accelerated accumulation of DNA single strand breaks, but not AP sites, over the PARP-1-proficient cells exposed to MMS. Mutat Res 2009; 671:93-9. [PMID: 19778542 DOI: 10.1016/j.mrfmmm.2009.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 08/31/2009] [Accepted: 09/16/2009] [Indexed: 10/20/2022]
Abstract
Poly(ADP-ribose) polymerase-1 (PARP-1) is a base excision repair (BER) protein that binds to DNA single strand breaks (SSBs) and subsequently synthesizes and transfers poly(ADP-ribose) polymers to various nuclear proteins. Numerous biochemical studies have implicated PARP-1 as a modulator of BER; however, the role of PARP-1 in BER in living cells remains unclear partly due to lack of accurate quantitation of BER intermediates existing in cells. Since DT40 cells, chicken B lymphocytes, naturally lack PARP-2, DT40 cells allow for the investigation of the PARP-1 null phenotype without confounding by PARP-2. To test the hypothesis that PARP-1 is necessary for efficient BER during methylmethane sulfonate (MMS) exposure in vertebrate cells, intact DT40 cells and their isogenic PARP-1 null counterparts were challenged with different exposure scenarios for phenotypic characterization. With chronic exposure, PARP-1 null cells exhibited sensitivity to MMS but with an acute exposure did not accumulate base lesions or AP sites to a greater extent than wild-type cells. However, an increase in SSB content in PARP-1 null cell DNA, as indicated by glyoxal gel electrophoresis under neutral conditions, suggested the presence of BER intermediates. These data suggest that during exposure, PARP-1 impacts the stage of BER after excision of the deoxyribosephosphate moiety from the 5' end of DNA strand breaks by polymerase beta.
Collapse
Affiliation(s)
- Brian F Pachkowski
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC, USA
| | | | | | | | | | | | | | | |
Collapse
|
33
|
The formation and biological significance of N7-guanine adducts. Mutat Res 2009; 678:76-94. [PMID: 19465146 DOI: 10.1016/j.mrgentox.2009.05.006] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 05/13/2009] [Indexed: 11/24/2022]
Abstract
DNA alkylation or adduct formation occurs at nucleophilic sites in DNA, mainly the N7-position of guanine. Ever since identification of the first N7-guanine adduct, several hundred studies on DNA adducts have been reported. Major issues addressed include the relationships between N7-guanine adducts and exposure, mutagenesis, and other biological endpoints. It became quickly apparent that N7-guanine adducts are frequently formed, but may have minimal biological relevance, since they are chemically unstable and do not participate in Watson Crick base pairing. However, N7-guanine adducts have been shown to be excellent biomarkers for internal exposure to direct acting and metabolically activated carcinogens. Questions arise, however, regarding the biological significance of N7-guanine adducts that are readily formed, do not persist, and are not likely to be mutagenic. Thus, we set out to review the current literature to evaluate their formation and the mechanistic evidence for the involvement of N7-guanine adducts in mutagenesis or other biological processes. It was concluded that there is insufficient evidence that N7-guanine adducts can be used beyond confirmation of exposure to the target tissue and demonstration of the molecular dose. There is little to no evidence that N7-guanine adducts or their depurination product, apurinic sites, are the cause of mutations in cells and tissues, since increases in AP sites have not been shown unless toxicity is extant. However, more research is needed to define the extent of chemical depurination versus removal by DNA repair proteins. Interestingly, N7-guanine adducts are clearly present as endogenous background adducts and the endogenous background amounts appear to increase with age. Furthermore, the N7-guanine adducts have been shown to convert to ring opened lesions (FAPy), which are much more persistent and have higher mutagenic potency. Studies in humans are limited in sample size and differences between controls and study groups are small. Future investigations should involve human studies with larger numbers of individuals and analysis should include the corresponding ring opened FAPy derivatives.
Collapse
|
34
|
Abstract
Mitochondrial DNA is thought to be especially prone to oxidative damage by reactive oxygen species generated through electron transport during cellular respiration. This damage is mitigated primarily by the base excision repair (BER) pathway, one of the few DNA repair pathways with confirmed activity on mitochondrial DNA. Through genetic epistasis analysis of the yeast Saccharomyces cerevisiae, we examined the genetic interaction between each of the BER proteins previously shown to localize to the mitochondria. In addition, we describe a series of genetic interactions between BER components and the MutS homolog MSH1, a respiration-essential gene. We show that, in addition to their variable effects on mitochondrial function, mutant msh1 alleles conferring partial function interact genetically at different points in mitochondrial BER. In addition to this separation of function, we also found that the role of Msh1p in BER is unlikely to be involved in the avoidance of large-scale deletions and rearrangements.
Collapse
|
35
|
Jiranusornkul S, Laughton CA. Destabilization of DNA duplexes by oxidative damage at guanine: implications for lesion recognition and repair. J R Soc Interface 2009; 5 Suppl 3:S191-8. [PMID: 18782724 DOI: 10.1098/rsif.2008.0304.focus] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We have used molecular dynamics simulations to study the structure and dynamics of a range of DNA duplexes containing the 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapydG) lesion that can result from oxidative damage at guanine. Compared to the corresponding undamaged DNA duplexes, FapydG-containing duplexes show little gross structural changes-the damaged base remains stacked in to the DNA double helix and retains hydrogen bonds to its cytosine partner. However, the experimentally observed reduction in DNA stability that accompanies lesion formation can be explained by a careful energetic analysis of the simulation data. Irrespective of the nature of the base pairs on either side of the lesion site, conversion of a guanine to a FapydG base results in increased dynamical flexibility in the base (but not in the DNA as a whole) that significantly weakens its hydrogen-bonding interactions. Surprisingly, the stacking interactions with its neighbours are not greatly altered. The formamido group adopts a non-planar conformation that can interact significantly and in a sequence-dependent manner with its 3'-neighbour. We conclude that the recognition of FapydG lesions by the repair protein formamidopyrimidine-DNA glycosylase probably does not involve the protein capturing an already-extrahelical FapydG base, but rather it relies on detecting alterations to the DNA structure and flexibility created by the lesion site.
Collapse
Affiliation(s)
- Supat Jiranusornkul
- School of Pharmacy and Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | | |
Collapse
|
36
|
Structural and biological impact of radical addition reactions with DNA nucleobases. ADVANCES IN PHYSICAL ORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0065-3160(08)00005-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
|
37
|
Dizdaroglu M, Kirkali G, Jaruga P. Formamidopyrimidines in DNA: mechanisms of formation, repair, and biological effects. Free Radic Biol Med 2008; 45:1610-21. [PMID: 18692130 DOI: 10.1016/j.freeradbiomed.2008.07.004] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 06/26/2008] [Accepted: 07/08/2008] [Indexed: 01/01/2023]
Abstract
Oxidatively induced damage to DNA results in a plethora of lesions comprising modified bases and sugars, DNA-protein cross-links, tandem lesions, strand breaks, and clustered lesions. Formamidopyrimidines, 4,6-diamino-5-formamidopyrimidine (FapyAde) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua), are among the major lesions generated in DNA by hydroxyl radical attack, UV radiation, or photosensitization under numerous in vitro and in vivo conditions. They are formed by one-electron reduction of C8-OH-adduct radicals of purines and thus have a common precursor with 8-hydroxypurines generated upon one-electron oxidation. Methodologies using mass spectrometry exist to accurately measure FapyAde and FapyGua in vitro and in vivo. Formamidopyrimidines are repaired by base excision repair. Numerous prokaryotic and eukaryotic DNA glycosylases are highly specific for removal of these lesions from DNA in the first step of this repair pathway, indicating their biological importance. FapyAde and FapyGua are bypassed by DNA polymerases with the insertion of the wrong intact base opposite them, leading to mutagenesis. In mammalian cells, the mutagenicity of FapyGua exceeds that of 8-hydroxyguanine, which is thought to be the most mutagenic of the oxidatively induced lesions in DNA. The background and formation levels of the former in vitro and in vivo equal or exceed those of the latter under various conditions. FapyAde and FapyGua exist in living cells at significant background levels and are abundantly generated upon exposure to oxidative stress. Mice lacking the genes that encode specific DNA glycosylases accumulate these lesions in different organs and, in some cases, exhibit a series of pathological conditions including metabolic syndrome and cancer. Animals exposed to environmental toxins accumulate formamidopyrimidines in their organs. Here, we extensively review the mechanisms of formation, measurement, repair, and biological effects of formamidopyrimidines that have been investigated in the past 50 years. Our goal is to emphasize the importance of these neglected lesions in many biological and disease processes.
Collapse
Affiliation(s)
- Miral Dizdaroglu
- Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
| | | | | |
Collapse
|
38
|
Cantrell WR, Lovett D, Engles T, Anderson B, Bauta WE, Wolstenholme-Hogg PC. Synthetic studies on formamidopyrimidines related to clofarabine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 27:901-13. [PMID: 18696361 DOI: 10.1080/15257770802257770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Degradation of clofarabine (3) in 0.9% saline solution at 100 degrees C afforded three degradation products which were determined to be formamidopyrimidines 4-6. Compounds 4 and 5 were assigned as C(1') anomers on the basis of one-dimensional and two-dimensional NMR experiments, whereas 6 was found to be the formamidopyrimidine lacking the sugar moiety. An improved procedure for the synthesis of formamidopyrimidines was developed, wherein benzoylated clofarabine (11) was treated with allyl chloroformate, followed by deprotection of the alloc group with catalytic Pd(PPh(3))(4) and dimedone. A synthesis of compound 6 from 4 is also described.
Collapse
Affiliation(s)
- William R Cantrell
- Genzyme Corporation, Quality and Technical Operations, San Antonio, Texas78229, USA
| | | | | | | | | | | |
Collapse
|
39
|
Coste F, Ober M, Le Bihan YV, Izquierdo MA, Hervouet N, Mueller H, Carell T, Castaing B. Bacterial Base Excision Repair Enzyme Fpg Recognizes Bulky N7-Substituted-FapydG Lesion via Unproductive Binding Mode. ACTA ACUST UNITED AC 2008; 15:706-17. [DOI: 10.1016/j.chembiol.2008.05.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Revised: 05/14/2008] [Accepted: 05/19/2008] [Indexed: 01/18/2023]
|
40
|
Ho J, Van Arsdale K, Braun M. Efficient Synthesis of14C-Labeled 1H-Pyrazolo[3,4-d]pyrimidine and Related [4.3.0]-Bicyclic Pyrimidino Systems. Helv Chim Acta 2008. [DOI: 10.1002/hlca.200890102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
41
|
dos Santos PE, Egito LCM, de Medeiros SRB, Agnez-Lima LF. Genotoxicity induced by Eugenia caryophyllata infusion. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2008; 71:439-444. [PMID: 18306091 DOI: 10.1080/15287390701839232] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Several therapeutic properties have been described for Eugenia caryophyllata (clove). In the present study the infusion of E. caryophyllata was evaluated in a series of bacterial and cell-free assays in order to determine genotoxic potential. Negative results were obtained in the SOS chromotest and in the Salmonella reversion assay using strains TA97a, TA98, TA100, and TA102. However, in a forward mutagenesis assay an increase in mutagenesis and high cytotoxicity was observed with the CC104 mutMmutY strain, suggesting that oxidative DNA damage occurred. The treatment of plasmid with clove infusion showed that DNA strand breaks and sites recognized by formamidopyrimidine-DNA-glycosylase (FPG/MutM) were generated. Data suggest that the occurrence of oxidative DNA damage, with low mutagenic potential, may also be involved in the cytotoxicity attributed to clove infusion.
Collapse
Affiliation(s)
- Patrícia Estevam dos Santos
- Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | | | | | | |
Collapse
|
42
|
Behr J, Israel L, Gänzle MG, Vogel RF. Proteomic approach for characterization of hop-inducible proteins in Lactobacillus brevis. Appl Environ Microbiol 2007; 73:3300-6. [PMID: 17369340 PMCID: PMC1907096 DOI: 10.1128/aem.00124-07] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Resistance to hops is a prerequisite for the capability of lactic acid bacteria to grow in beer and thus cause beer spoilage. Bactericidal hop compounds, mainly iso-alpha-acids, are described as ionophores which exchange H+ for cellular divalent cations, e.g., Mn2+, and thus dissipate ion gradients across the cytoplasmic membrane. The acid stress response of Lactobacillus brevis TMW 1.465 and hop adaptation in its variant L. brevis TMW 1.465A caused changes at the level of metabolism, membrane physiology, and cell wall composition. To identify the basis for these changes, a proteomic approach was taken. The experimental design allowed the discrimination of acid stress and hop stress. A strategy for improved protein identification enabled the identification of 84% of the proteins investigated despite the lack of genome sequence data for this strain. Hop resistance in L. brevis TMW 1.465A implies mechanisms to cope with intracellular acidification, mechanisms for energy generation and economy, genetic information fidelity, and enzyme functionality. Interestingly, the majority of hop-regulated enzymes are described as manganese or divalent cation dependent. Regulation of the manganese level allows fine-tuning of the metabolism, which enables a rapid response to environmental (stress) conditions. The hop stress response indicates adaptations shifting the metabolism into an energy-saving mode by effective substrate conversion and prevention of exhaustive protein de novo synthesis. The findings further demonstrate that hop stress in bacteria not only is associated with proton motive force depletion but obviously implies divalent cation limitation.
Collapse
Affiliation(s)
- Jürgen Behr
- Technische Mikrobiologie, Technische Universität München, Weihenstephaner Steig 16, 85350 Freising, Germany
| | | | | | | |
Collapse
|
43
|
Akatsuka S, Aung TT, Dutta KK, Jiang L, Lee WH, Liu YT, Onuki J, Shirase T, Yamasaki K, Ochi H, Naito Y, Yoshikawa T, Kasai H, Tominaga Y, Sakumi K, Nakabeppu Y, Kawai Y, Uchida K, Yamasaki A, Tsuruyama T, Yamada Y, Toyokuni S. Contrasting genome-wide distribution of 8-hydroxyguanine and acrolein-modified adenine during oxidative stress-induced renal carcinogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2006; 169:1328-42. [PMID: 17003489 PMCID: PMC1780183 DOI: 10.2353/ajpath.2006.051280] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Oxidative stress is a persistent threat to the genome and is associated with major causes of human mortality, including cancer, atherosclerosis, and aging. Here we established a method to generate libraries of genomic DNA fragments containing oxidatively modified bases by using specific monoclonal antibodies to immunoprecipitate enzyme-digested genome DNA. We applied this technique to two different base modifications, 8-hydroxyguanine and 1,N6-propanoadenine (acrotein-Ade), in a ferric nitrilotriacetate-induced murine renal carcinogenesis model. Renal cortical genomic DNA derived from 10- to 12-week-old male C57BL/6 mice, of untreated control or 6 hours after intraperitoneal injection of 3 mg iron/kg ferric nitrilotriacetate, was enzyme digested, immunoprecipitated, cloned, and mapped to each chromosome. The results revealed that distribution of the two modified bases was not random but differed in terms of chromosomes, gene size, and expression, which could be partially explained by chromosomal territory. In the wild-type mice, low GC content areas were more likely to harbor the two modified bases. Knockout of OGG1, a repair enzyme for genomic 8-hydroxyguanine, increased the amounts of acrolein-Ade as determined by quantitative polymerase chain reaction analyses. This versatile technique would introduce a novel research area as a high-throughput screening method for critical genomic loci under oxidative stress.
Collapse
Affiliation(s)
- Shinya Akatsuka
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Lacoste S, Castonguay A, Drouin R. Formamidopyrimidine adducts are detected using the comet assay in human cells treated with reactive metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Mutat Res 2006; 600:138-49. [PMID: 16914170 DOI: 10.1016/j.mrfmmm.2006.04.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Revised: 03/17/2006] [Accepted: 04/02/2006] [Indexed: 11/18/2022]
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is the most lung-specific of the carcinogens present in tobacco smoke. Its bioactivation in cells leads to a small amount of methylation or pyridyloxobutylation DNA damage. Considering its great sensitivity, the comet assay seems a technique of choice to investigate NNK-related damage. Several strategies were used to impart some specificity to the assay: (1) using analogs that produce a limited variety of DNA lesions, as they mimic either the methylation or the pyridyloxobutylation pathway; (2) using cells with different bioactivation abilities; (3) using alkali conversion and/or enzymes specific for cleaving particular classes of damage; (4) using different lysis conditions to convert a specific class of DNA lesions into enzyme-sensitive lesions. We determined that several NNK-associated lesions can be detected with some specificity with the comet assay. For the methylation pathway, they are AP sites and the more frequent formamidopyrimidine (fapy) adducts. These fapy adducts correspond to N7-methylguanines generated in the cells that were ring-opened during the assay by the lysis solution at pH 10. For the pyridyloxobutylation pathway, alkylphosphotriesters and a roughly equal frequency of fapy sites were detected. By analogy to the methylation damage, these fapy adducts are thought to be the ring-opened form of N7-pyridyloxobutylguanines (N7-pobG). N7-pobG are unstable and this constitutes the first indirect demonstration of their formation in cells. But contrary to N7-m-fapy, the lysis time or pH did not influence the frequency of N7-pob-fapy adducts detected, suggesting that they already exist in the cells and are not related to the experimental conditions. These N7-pob-fapy have a strong mutagenic potential and we think that the comet assay, in spite of its limitations, is a good way to study them considering their low frequency and the inherent instability of the adduct from which they originate.
Collapse
Affiliation(s)
- Sandrine Lacoste
- Service of Genetics, Department of Paediatrics, Faculty of Medicine and Health Sciences, University of Sherbrooke, 3001, 12th Avenue North, Sherbrooke, Que., Canada J1H 5N4
| | | | | |
Collapse
|
45
|
de Jésus KP, Serre L, Zelwer C, Castaing B. Structural insights into abasic site for Fpg specific binding and catalysis: comparative high-resolution crystallographic studies of Fpg bound to various models of abasic site analogues-containing DNA. Nucleic Acids Res 2005; 33:5936-44. [PMID: 16243784 PMCID: PMC1266061 DOI: 10.1093/nar/gki879] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Fpg is a DNA glycosylase that recognizes and excises the mutagenic 8-oxoguanine (8-oxoG) and the potentially lethal formamidopyrimidic residues (Fapy). Fpg is also associated with an AP lyase activity which successively cleaves the abasic (AP) site at the 3′ and 5′ sides by βδ-elimination. Here, we present the high-resolution crystal structures of the wild-type and the P1G defective mutant of Fpg from Lactococcus lactis bound to 14mer DNA duplexes containing either a tetrahydrofuran (THF) or 1,3-propanediol (Pr) AP site analogues. Structures show that THF is less extrahelical than Pr and its backbone C5′–C4′–C3′ diverges significantly from those of Pr, rAP, 8-oxodG and FapydG. Clearly, the heterocyclic oxygen of THF is pushed back by the carboxylate of the strictly conserved E2 residue. We can propose that the ring-opened form of the damaged deoxyribose is the structure active form of the sugar for Fpg catalysis process. Both structural and functional data suggest that the first step of catalysis mediated by Fpg involves the expulsion of the O4′ leaving group facilitated by general acid catalysis (involving E2), rather than the immediate cleavage of the N-glycosic bond of the damaged nucleoside.
Collapse
Affiliation(s)
| | - Laurence Serre
- Institut de Biologie Structurale, CEA-CNRS-UJF41 rue Jules Horowitz, 38027 Grenoble cedex 01, France
| | | | - Bertrand Castaing
- To whom correspondence should be addressed. Tel: +33 2 38 25 78 43; Fax: +33 2 38 63 15 17;
| |
Collapse
|