1
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Tomar R, Ghodke PP, Patra A, Smyth E, Pontarelli A, Copp W, Guengerich FP, Chaput JJ, Wilds CJ, Stone MP, Egli M. DNA Replication across α-l-(3'-2')-Threofuranosyl Nucleotides Mediated by Human DNA Polymerase η. Biochemistry 2024. [PMID: 39259676 DOI: 10.1021/acs.biochem.4c00387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2024]
Abstract
α-l-(3'-2')-Threofuranosyl nucleic acid (TNA) pairs with itself, cross-pairs with DNA and RNA, and shows promise as a tool in synthetic genetics, diagnostics, and oligonucleotide therapeutics. We studied in vitro primer insertion and extension reactions catalyzed by human trans-lesion synthesis (TLS) DNA polymerase η (hPol η) opposite a TNA-modified template strand without and in combination with O4-alkyl thymine lesions. Across TNA-T (tT), hPol η inserted mostly dAMP and dGMP, dTMP and dCMP with lower efficiencies, followed by extension of the primer to a full-length product. hPol η inserted dAMP opposite O4-methyl and -ethyl analogs of tT, albeit with reduced efficiencies relative to tT. Crystal structures of ternary hPol η complexes with template tT and O4-methyl tT at the insertion and extension stages demonstrated that the shorter backbone and different connectivity of TNA compared to DNA (3' → 2' versus 5' → 3', respectively) result in local differences in sugar orientations, adjacent phosphate spacings, and directions of glycosidic bonds. The 3'-OH of the primer's terminal thymine was positioned at 3.4 Å on average from the α-phosphate of the incoming dNTP, consistent with insertion opposite and extension past the TNA residue by hPol η. Conversely, the crystal structure of a ternary hPol η·DNA·tTTP complex revealed that the primer's terminal 3'-OH was too distant from the tTTP α-phosphate, consistent with the inability of the polymerase to incorporate TNA. Overall, our study provides a better understanding of the tolerance of a TLS DNA polymerase vis-à-vis unnatural nucleotides in the template and as the incoming nucleoside triphosphate.
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Affiliation(s)
- Rachana Tomar
- Department of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Pratibha P Ghodke
- Department of Biochemistry, School of Medicine, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Amritraj Patra
- Department of Biochemistry, School of Medicine, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Elizabeth Smyth
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec H4B 1R6, Canada
| | - Alexander Pontarelli
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec H4B 1R6, Canada
| | - William Copp
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec H4B 1R6, Canada
| | - F Peter Guengerich
- Department of Biochemistry, School of Medicine, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - John J Chaput
- Department of Pharmaceutical Sciences, University of California, Irvine, California 92697, United States
| | - Christopher J Wilds
- Department of Chemistry and Biochemistry, Concordia University, Montréal, Québec H4B 1R6, Canada
| | - Michael P Stone
- Department of Chemistry, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Martin Egli
- Department of Biochemistry, School of Medicine, Vanderbilt Ingram Cancer Center, and Vanderbilt Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
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2
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Carvajal-Maldonado D, Li Y, Returan M, Averill AM, Doublié S, Wood RD. Dynamic stem-loop extension by Pol θ and templated insertion during DNA repair. J Biol Chem 2024; 300:107461. [PMID: 38876299 PMCID: PMC11292364 DOI: 10.1016/j.jbc.2024.107461] [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: 04/17/2024] [Revised: 05/26/2024] [Accepted: 05/28/2024] [Indexed: 06/16/2024] Open
Abstract
Theta-mediated end joining (TMEJ) is critical for survival of cancer cells when other DNA double-stranded break repair pathways are impaired. Human DNA polymerase theta (Pol θ) can extend ssDNA oligonucleotides, but little is known about preferred substrates and mechanism. We show that Pol θ can extend both ssDNA and RNA substrates by unimolecular stem-loop synthesis initiated by only two 3' terminal base pairs. Given sufficient time, Pol θ uses alternative pairing configurations that greatly expand the repertoire of sequence outcomes. Further primer-template adjustments yield low-fidelity outcomes when the nucleotide pool is imbalanced. Unimolecular stem-loop synthesis competes with bimolecular end joining, even when a longer terminal microhomology for end joining is available. Both reactions are partially suppressed by the ssDNA-binding protein replication protein A. Protein-primer grasp residues that are specific to Pol θ are needed for rapid stem-loop synthesis. The ability to perform stem-loop synthesis from a minimally paired primer is rare among human DNA polymerases, but we show that human DNA polymerases Pol η and Pol λ can catalyze related reactions. Using purified human Pol θ, we reconstituted in vitro TMEJ incorporating an insertion arising from a stem-loop extension. These activities may help explain TMEJ repair events that include inverted repeat sequences.
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Affiliation(s)
- Denisse Carvajal-Maldonado
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - Yuzhen Li
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - Mark Returan
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA
| | - April M Averill
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA.
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3
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Steele EJ, Franklin A, Lindley RA. Somatic mutation patterns at Ig and Non-Ig Loci. DNA Repair (Amst) 2024; 133:103607. [PMID: 38056368 DOI: 10.1016/j.dnarep.2023.103607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 11/17/2023] [Accepted: 11/21/2023] [Indexed: 12/08/2023]
Abstract
The reverse transcriptase (RT) model of immunoglobulin (Ig) somatic hypermutation (SHM) has received insufficient scientific attention. This is understandable given that DNA deamination mediated by activation-induced deaminase (AID), the initiating step of Ig SHM, has dominated experiments since 2002. We summarise some key history of the RT Ig SHM model dating to 1987. For example, it is now established that DNA polymerase η, the sole DNA repair polymerase involved in post-replication short-patch repair, is an efficient cellular RT. This implies that it is potentially able to initiate target site reverse transcription by RNA-directed DNA repair at AID-induced lesions. Recently, DNA polymerase θ has also been shown to be an efficient cellular RT. Since DNA polymerase θ plays no significant role in Ig SHM, it could serve a similar RNA-dependent DNA polymerase role as DNA polymerase η at non-Ig loci in the putative RNA-templated nucleotide excision repair of bulky adducts and other mutagenic lesions on the transcribed strand. A major yet still poorly recognised consequence of the proposed RT process in Ig SHM is the generation of significant and characteristic strand-biased mutation signatures at both deoxyadenosine/deoxythymidine and deoxyguanosine/deoxycytidine base pairs. In this historical perspective, we highlight how diagnostic strand-biased mutation signatures are detected in vivo during SHM at both Ig loci in germinal centre B lymphocytes and non-Ig loci in cancer genomes. These strand-biased signatures have been significantly obscured by technical issues created by improper use of the polymerase chain reaction technique. A heightened awareness of this fact should contribute to better data interpretation and somatic mutation pattern recognition both at Ig and non-Ig loci.
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Affiliation(s)
- Edward J Steele
- Melville Analytics Pty Ltd, 2/102 Duke St, Kangaroo Point, Brisbane 4169, Qld, Australia.
| | - Andrew Franklin
- Novartis Pharmaceuticals UK Limited, The WestWorks Building, White City Place, 195 Wood Lane, W12 7FQ London, United Kingdom
| | - Robyn A Lindley
- GMDxgenomics, Suite 201, 697 Burke Rd, Camberwell, Melbourne 3124, Vic, Australia; Department of Clinical Pathology, Faculty of Medicine, Dentistry & Health Sciences, University of Melbourne, Vic, Australia
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4
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Balint E, Unk I. For the Better or for the Worse? The Effect of Manganese on the Activity of Eukaryotic DNA Polymerases. Int J Mol Sci 2023; 25:363. [PMID: 38203535 PMCID: PMC10779026 DOI: 10.3390/ijms25010363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/12/2024] Open
Abstract
DNA polymerases constitute a versatile group of enzymes that not only perform the essential task of genome duplication but also participate in various genome maintenance pathways, such as base and nucleotide excision repair, non-homologous end-joining, homologous recombination, and translesion synthesis. Polymerases catalyze DNA synthesis via the stepwise addition of deoxynucleoside monophosphates to the 3' primer end in a partially double-stranded DNA. They require divalent metal cations coordinated by active site residues of the polymerase. Mg2+ is considered the likely physiological activator because of its high cellular concentration and ability to activate DNA polymerases universally. Mn2+ can also activate the known DNA polymerases, but in most cases, it causes a significant decrease in fidelity and/or processivity. Hence, Mn2+ has been considered mutagenic and irrelevant during normal cellular function. Intriguingly, a growing body of evidence indicates that Mn2+ can positively influence some DNA polymerases by conferring translesion synthesis activity or altering the substrate specificity. Here, we review the relevant literature focusing on the impact of Mn2+ on the biochemical activity of a selected set of polymerases, namely, Polβ, Polλ, and Polµ, of the X family, as well as Polι and Polη of the Y family of polymerases, where congruous data implicate the physiological relevance of Mn2+ in the cellular function of these enzymes.
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Affiliation(s)
| | - Ildiko Unk
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, H-6726 Szeged, Hungary;
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5
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Chakraborty A, Tapryal N, Islam A, Sarker AH, Manohar K, Mitra J, Hegde ML, Hazra T. Human DNA polymerase η promotes RNA-templated error-free repair of DNA double-strand breaks. J Biol Chem 2023; 299:102991. [PMID: 36758800 PMCID: PMC10011834 DOI: 10.1016/j.jbc.2023.102991] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/20/2023] [Accepted: 01/31/2023] [Indexed: 02/10/2023] Open
Abstract
A growing body of evidence indicates that RNA plays a critical role in orchestrating DNA double-strand break repair (DSBR). Recently, we showed that homologous nascent RNA can be used as a template for error-free repair of double-strand breaks (DSBs) in the transcribed genome and to restore the missing sequence at the break site via the transcription-coupled classical nonhomologous end-joining (TC-NHEJ) pathway. TC-NHEJ is a complex multistep process in which a reverse transcriptase (RT) is essential for synthesizing the DNA strand from template RNA. However, the identity of the RT involved in the TC-NHEJ pathway remained unknown. Here, we report that DNA polymerase eta (Pol η), known to possess RT activity, plays a critical role in TC-NHEJ. We found that Pol η forms a multiprotein complex with RNAP II and other TC-NHEJ factors, while also associating with nascent RNA. Moreover, purified Pol η, along with DSBR proteins PNKP, XRCC4, and Ligase IV can fully repair RNA templated 3'-phosphate-containing gapped DNA substrate. In addition, we demonstrate here that Pol η deficiency leads to accumulation of R-loops and persistent strand breaks in the transcribed genes. Finally, we determined that, in Pol η depleted but not in control cells, TC-NHEJ-mediated repair was severely abrogated when a reporter plasmid containing a DSB with several nucleotide deletion within the E. coli lacZ gene was introduced for repair in lacZ-expressing mammalian cells. Thus, our data strongly suggest that RT activity of Pol η is required in error-free DSBR.
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Affiliation(s)
- Anirban Chakraborty
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Nisha Tapryal
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Azharul Islam
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Altaf H Sarker
- Life Sciences Division, Department of Cancer and DNA Damage Responses, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Kodavati Manohar
- Department of Neurosurgery, Center for Neuroregeneration, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Joy Mitra
- Department of Neurosurgery, Center for Neuroregeneration, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Muralidhar L Hegde
- Department of Neurosurgery, Center for Neuroregeneration, The Houston Methodist Research Institute, Houston, Texas, USA
| | - Tapas Hazra
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
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6
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Multifaceted Nature of DNA Polymerase θ. Int J Mol Sci 2023; 24:ijms24043619. [PMID: 36835031 PMCID: PMC9962433 DOI: 10.3390/ijms24043619] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/26/2023] [Accepted: 02/02/2023] [Indexed: 02/15/2023] Open
Abstract
DNA polymerase θ belongs to the A family of DNA polymerases and plays a key role in DNA repair and damage tolerance, including double-strand break repair and DNA translesion synthesis. Pol θ is often overexpressed in cancer cells and promotes their resistance to chemotherapeutic agents. In this review, we discuss unique biochemical properties and structural features of Pol θ, its multiple roles in protection of genome stability and the potential of Pol θ as a target for cancer treatment.
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7
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Primer terminal ribonucleotide alters the active site dynamics of DNA polymerase η and reduces DNA synthesis fidelity. J Biol Chem 2023; 299:102938. [PMID: 36702254 PMCID: PMC9976465 DOI: 10.1016/j.jbc.2023.102938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 01/25/2023] Open
Abstract
DNA polymerases catalyze DNA synthesis with high efficiency, which is essential for all life. Extensive kinetic and structural efforts have been executed in exploring mechanisms of DNA polymerases, surrounding their kinetic pathway, catalytic mechanisms, and factors that dictate polymerase fidelity. Recent time-resolved crystallography studies on DNA polymerase η (Pol η) and β have revealed essential transient events during the DNA synthesis reaction, such as mechanisms of primer deprotonation, separated roles of the three metal ions, and conformational changes that disfavor incorporation of the incorrect substrate. DNA-embedded ribonucleotides (rNs) are the most common lesion on DNA and a major threat to genome integrity. While kinetics of rN incorporation has been explored and structural studies have revealed that DNA polymerases have a steric gate that destabilizes ribonucleotide triphosphate binding, the mechanism of extension upon rN addition remains poorly characterized. Using steady-state kinetics, static and time-resolved X-ray crystallography with Pol η as a model system, we showed that the extra hydroxyl group on the primer terminus does alter the dynamics of the polymerase active site as well as the catalysis and fidelity of DNA synthesis. During rN extension, Pol η error incorporation efficiency increases significantly across different sequence contexts. Finally, our systematic structural studies suggest that the rN at the primer end improves primer alignment and reduces barriers in C2'-endo to C3'-endo sugar conformational change. Overall, our work provides further mechanistic insights into the effects of rN incorporation on DNA synthesis.
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8
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Eckert KA. Nontraditional Roles of DNA Polymerase Eta Support Genome Duplication and Stability. Genes (Basel) 2023; 14:genes14010175. [PMID: 36672916 PMCID: PMC9858799 DOI: 10.3390/genes14010175] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/03/2023] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
DNA polymerase eta (Pol η) is a Y-family polymerase and the product of the POLH gene. Autosomal recessive inheritance of POLH mutations is the cause of the xeroderma pigmentosum variant, a cancer predisposition syndrome. This review summarizes mounting evidence for expanded Pol η cellular functions in addition to DNA lesion bypass that are critical for maintaining genome stability. In vitro, Pol η displays efficient DNA synthesis through difficult-to-replicate sequences, catalyzes D-loop extensions, and utilizes RNA-DNA hybrid templates. Human Pol η is constitutively present at the replication fork. In response to replication stress, Pol η is upregulated at the transcriptional and protein levels, and post-translational modifications regulate its localization to chromatin. Numerous studies show that Pol η is required for efficient common fragile site replication and stability. Additionally, Pol η can be recruited to stalled replication forks through protein-protein interactions, suggesting a broader role in replication fork recovery. During somatic hypermutations, Pol η is recruited by mismatch repair proteins and is essential for VH gene A:T basepair mutagenesis. Within the global context of repeat-dense genomes, the recruitment of Pol η to perform specialized functions during replication could promote genome stability by interrupting pure repeat arrays with base substitutions. Alternatively, not engaging Pol η in genome duplication is costly, as the absence of Pol η leads to incomplete replication and increased chromosomal instability.
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Affiliation(s)
- Kristin A Eckert
- Gittlen Cancer Research Laboratories, Department of Pathology, Penn State University College of Medicine, 500 University Drive, Hershey, PA 17036, USA
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9
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Tsegay PS, Hernandez D, Qu F, Olatunji M, Mamun Y, Chapagain P, Liu Y. RNA-guided DNA base damage repair via DNA polymerase-mediated nick translation. Nucleic Acids Res 2022; 51:166-181. [PMID: 36533524 PMCID: PMC9841414 DOI: 10.1093/nar/gkac1178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/28/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
DNA repair is mediated by DNA synthesis guided by a DNA template. Recent studies have shown that DNA repair can also be accomplished by RNA-guided DNA synthesis. However, it remains unknown how RNA can guide DNA synthesis to repair DNA damage. In this study, we revealed the molecular mechanisms underlying RNA-guided DNA synthesis and base damage repair mediated by human repair DNA polymerases. We showed that pol β, pol κ, and pol ι predominantly synthesized one nucleotide, and pol η, pol ν, and pol θ synthesized multi-nucleotides during RNA-guided DNA base damage repair. The steady-state kinetics showed that pol η exhibited more efficient RNA-guided DNA synthesis than pol β. Using molecular dynamics simulation, we further revealed dynamic conformational changes of pol β and pol η and their structural basis to accommodate the RNA template and misoriented triphosphates of an incoming nucleotide. We demonstrated that RNA-guided base damage repair could be accomplished by the RNA-guided DNA strand-displacement synthesis and nick translation leading to nick ligation in a double-strand DNA region. Our study revealed a novel RNA-guided base damage repair pathway during transcription and DNA replication.
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Affiliation(s)
- Pawlos S Tsegay
- Biochemistry Ph.D. Program, Florida International University, Miami, FL, USA
| | - Daniela Hernandez
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, USA
| | - Fei Qu
- Biochemistry Ph.D. Program, Florida International University, Miami, FL, USA
| | - Mustapha Olatunji
- Biochemistry Ph.D. Program, Florida International University, Miami, FL, USA
| | - Yasir Mamun
- Biochemistry Ph.D. Program, Florida International University, Miami, FL, USA
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, FL, USA,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Yuan Liu
- To whom correspondence should be addressed. Tel: +1 305 348 3628; Fax: +1 305 348 2772;
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10
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Size- and Stereochemistry-Dependent Transcriptional Bypass of DNA Alkyl Phosphotriester Adducts in Mammalian Cells. DNA 2022; 2:221-230. [PMID: 36911626 PMCID: PMC9997456 DOI: 10.3390/dna2040016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Environmental, endogenous and therapeutic alkylating agents can react with internucleotide phosphate groups in DNA to yield alkyl phosphotriester (PTE) adducts. Alkyl-PTEs are induced at relatively high frequencies and are persistent in mammalian tissues; however, their biological consequences in mammalian cells have not been examined. Herein, we assessed how alkyl-PTEs with different alkyl group sizes and stereochemical configurations (S P and R P diastereomers of Me and nPr) affect the efficiency and fidelity of transcription in mammalian cells. We found that, while the R P diastereomer of Me- and nPr-PTEs constituted moderate and strong blockages to transcription, respectively, the S P diastereomer of the two lesions did not appreciably perturb transcription efficiency. In addition, none of the four alkyl-PTEs induced mutant transcripts. Furthermore, polymerase η assumed an important role in promoting transcription across the S P-Me-PTE, but not any of other three lesions. Loss of other translesion synthesis (TLS) polymerases tested, including Pol κ, Pol ι, Pol ξ and REV1, did not alter the transcription bypass efficiency or mutation frequency for any of the alkyl-PTE lesions. Together, our study provided important new knowledge about the impact of alkyl-PTE lesions on transcription and expanded the substrate pool of Pol η in transcriptional bypass.
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11
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Carvajal-Maldonado D, Drogalis Beckham L, Wood RD, Doublié S. When DNA Polymerases Multitask: Functions Beyond Nucleotidyl Transfer. Front Mol Biosci 2022; 8:815845. [PMID: 35071329 PMCID: PMC8782244 DOI: 10.3389/fmolb.2021.815845] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
DNA polymerases catalyze nucleotidyl transfer, the central reaction in synthesis of DNA polynucleotide chains. They function not only in DNA replication, but also in diverse aspects of DNA repair and recombination. Some DNA polymerases can perform translesion DNA synthesis, facilitating damage tolerance and leading to mutagenesis. In addition to these functions, many DNA polymerases conduct biochemically distinct reactions. This review presents examples of DNA polymerases that carry out nuclease (3'-5' exonuclease, 5' nuclease, or end-trimming nuclease) or lyase (5' dRP lyase) extracurricular activities. The discussion underscores how DNA polymerases have a remarkable ability to manipulate DNA strands, sometimes involving relatively large intramolecular movement.
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Affiliation(s)
- Denisse Carvajal-Maldonado
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX, United States
| | - Lea Drogalis Beckham
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, TX, United States
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
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12
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Balint E, Unk I. Manganese Is a Strong Specific Activator of the RNA Synthetic Activity of Human Polη. Int J Mol Sci 2021; 23:ijms23010230. [PMID: 35008656 PMCID: PMC8745064 DOI: 10.3390/ijms23010230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/21/2021] [Accepted: 12/23/2021] [Indexed: 12/02/2022] Open
Abstract
DNA polymerase η (Polη) is a translesion synthesis polymerase that can bypass different DNA lesions with varying efficiency and fidelity. Its most well-known function is the error-free bypass of ultraviolet light-induced cyclobutane pyrimidine dimers. The lack of this unique ability in humans leads to the development of a cancer-predisposing disease, the variant form of xeroderma pigmentosum. Human Polη can insert rNTPs during DNA synthesis, though with much lower efficiency than dNTPs, and it can even extend an RNA chain with ribonucleotides. We have previously shown that Mn2+ is a specific activator of the RNA synthetic activity of yeast Polη that increases the efficiency of the reaction by several thousand-fold over Mg2+. In this study, our goal was to investigate the metal cofactor dependence of RNA synthesis by human Polη. We found that out of the investigated metal cations, only Mn2+ supported robust RNA synthesis. Steady state kinetic analysis showed that Mn2+ activated the reaction a thousand-fold compared to Mg2+, even during DNA damage bypass opposite 8-oxoG and TT dimer. Our results revealed a two order of magnitude higher affinity of human Polη towards ribonucleotides in the presence of Mn2+ compared to Mg2+. It is noteworthy that activation occurred without lowering the base selectivity of the enzyme on undamaged templates, whereas the fidelity decreased across a TT dimer. In summary, our data strongly suggest that, like with its yeast homolog, Mn2+ is the proper metal cofactor of hPolη during RNA chain extension, and selective metal cofactor utilization contributes to switching between its DNA and RNA synthetic activities.
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13
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Franklin A, Steele EJ. RNA-directed DNA repair and antibody somatic hypermutation. Trends Genet 2021; 38:426-436. [PMID: 34740453 DOI: 10.1016/j.tig.2021.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/03/2021] [Accepted: 10/04/2021] [Indexed: 10/19/2022]
Abstract
Somatic hypermutation at antibody loci affects both deoxyadenosine-deoxythymidine (A/T) and deoxycytidine-deoxyguanosine (C/G) pairs. Deamination of C to deoxyuridine (U) by activation-induced deaminase (AID) explains how mutation at C/G pairs is potentiated. Mutation at A/T pairs is triggered during the initial stages of repair of AID-generated U lesions and occurs through an as yet unknown mechanism in which polymerase η has a major role. Recent evidence confirms that human polymerase η can act as a reverse transcriptase. Here, we compare the popular suggestion of mutation at A/T pairs through nucleotide mispairing (owing to polymerase error) during short-patch repair synthesis with the alternative proposal of mutation at A/T pairs through RNA editing and RNA-directed DNA repair.
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Affiliation(s)
- Andrew Franklin
- Novartis Pharma AG, Novartis Campus, 4056, Basel, Switzerland.
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14
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Guengerich FP, Ghodke PP. Etheno adducts: from tRNA modifications to DNA adducts and back to miscoding ribonucleotides. Genes Environ 2021; 43:24. [PMID: 34130743 PMCID: PMC8207595 DOI: 10.1186/s41021-021-00199-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/03/2021] [Indexed: 11/19/2022] Open
Abstract
Etheno (and ethano) derivatives of nucleic acid bases have an extra 5-membered ring attached. These were first noted as wyosine bases in tRNAs. Some were fluorescent, and the development of etheno derivatives of adenosine, cytosine, and guanosine led to the synthesis of fluorescent analogs of ATP, NAD+, and other cofactors for use in biochemical studies. Early studies with the carcinogen vinyl chloride revealed that these modified bases were being formed in DNA and RNA and might be responsible for mutations and cancer. The etheno bases are also derived from other carcinogenic vinyl monomers. Further work showed that endogenous etheno DNA adducts were present in animals and humans and are derived from lipid peroxidation. The chemical mechanisms of etheno adduct formation involve reactions with bis-electrophiles generated by cytochrome P450 enzymes or lipid peroxidation, which have been established in isotopic labeling studies. The mechanisms by which etheno DNA adducts miscode have been studied with several DNA polymerases, aided by the X-ray crystal structures of these polymerases in mispairing situations and in extension beyond mispairs. Repair of etheno DNA adduct damage is done primarily by glycosylases and also by the direct action of dioxygenases. Some human DNA polymerases (η, κ) can insert bases opposite etheno adducts in DNA and RNA, and the reverse transcriptase activity may be of relevance with the RNA etheno adducts. Further questions involve the extent that the etheno adducts contribute to human cancer.
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Affiliation(s)
- F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, 638B Robinson Research Building, 2200 Pierce Avenue, Nashville, TN, 37232-0146, USA.
| | - Pratibha P Ghodke
- Department of Biochemistry, Vanderbilt University School of Medicine, 638B Robinson Research Building, 2200 Pierce Avenue, Nashville, TN, 37232-0146, USA
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15
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Chandramouly G, Zhao J, McDevitt S, Rusanov T, Hoang T, Borisonnik N, Treddinick T, Lopezcolorado FW, Kent T, Siddique LA, Mallon J, Huhn J, Shoda Z, Kashkina E, Brambati A, Stark JM, Chen XS, Pomerantz RT. Polθ reverse transcribes RNA and promotes RNA-templated DNA repair. SCIENCE ADVANCES 2021; 7:7/24/eabf1771. [PMID: 34117057 PMCID: PMC8195485 DOI: 10.1126/sciadv.abf1771] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 04/23/2021] [Indexed: 05/12/2023]
Abstract
Genome-embedded ribonucleotides arrest replicative DNA polymerases (Pols) and cause DNA breaks. Whether mammalian DNA repair Pols efficiently use template ribonucleotides and promote RNA-templated DNA repair synthesis remains unknown. We find that human Polθ reverse transcribes RNA, similar to retroviral reverse transcriptases (RTs). Polθ exhibits a significantly higher velocity and fidelity of deoxyribonucleotide incorporation on RNA versus DNA. The 3.2-Å crystal structure of Polθ on a DNA/RNA primer-template with bound deoxyribonucleotide reveals that the enzyme undergoes a major structural transformation within the thumb subdomain to accommodate A-form DNA/RNA and forms multiple hydrogen bonds with template ribose 2'-hydroxyl groups like retroviral RTs. Last, we find that Polθ promotes RNA-templated DNA repair in mammalian cells. These findings suggest that Polθ was selected to accommodate template ribonucleotides during DNA repair.
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Affiliation(s)
- Gurushankar Chandramouly
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jiemin Zhao
- Molecular and Computational Biology, USC Dornsife Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Shane McDevitt
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Timur Rusanov
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Trung Hoang
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Nikita Borisonnik
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Taylor Treddinick
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Tatiana Kent
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Labiba A Siddique
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Joseph Mallon
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jacklyn Huhn
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Zainab Shoda
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ekaterina Kashkina
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Alessandra Brambati
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Jeremy M Stark
- Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, USC Dornsife Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Richard T Pomerantz
- Department of Biochemistry and Molecular Biology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA.
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16
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Selective Metal Ion Utilization Contributes to the Transformation of the Activity of Yeast Polymerase η from DNA Polymerization toward RNA Polymerization. Int J Mol Sci 2020; 21:ijms21218248. [PMID: 33158019 PMCID: PMC7672554 DOI: 10.3390/ijms21218248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 12/16/2022] Open
Abstract
Polymerase eta (Polη) is a translesion synthesis DNA polymerase directly linked to cancer development. It can bypass several DNA lesions thereby rescuing DNA damage-stalled replication complexes. We previously presented evidence implicating Saccharomyces cerevisiae Polη in transcription elongation, and identified its specific RNA extension and translesion RNA synthetic activities. However, RNA synthesis by Polη proved rather inefficient under conditions optimal for DNA synthesis. Searching for factors that could enhance its RNA synthetic activity, we have identified the divalent cation of manganese. Here, we show that manganese triggers drastic changes in the activity of Polη. Kinetics experiments indicate that manganese increases the efficiency of ribonucleoside incorporation into RNA by ~400–2000-fold opposite undamaged DNA, and ~3000 and ~6000-fold opposite TT dimer and 8oxoG, respectively. Importantly, preference for the correct base is maintained with manganese during RNA synthesis. In contrast, activity is strongly impaired, and base discrimination is almost lost during DNA synthesis by Polη with manganese. Moreover, Polη shows strong preference for manganese during RNA synthesis even at a 25-fold excess magnesium concentration. Based on this, we suggest that a new regulatory mechanism, selective metal cofactor utilization, modulates the specificity of Polη helping it to perform distinct activities needed for its separate functions during replication and transcription.
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17
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Zhang H. Mechanisms of mutagenesis induced by DNA lesions: multiple factors affect mutations in translesion DNA synthesis. Crit Rev Biochem Mol Biol 2020; 55:219-251. [PMID: 32448001 DOI: 10.1080/10409238.2020.1768205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Environmental mutagens lead to mutagenesis. However, the mechanisms are very complicated and not fully understood. Environmental mutagens produce various DNA lesions, including base-damaged or sugar-modified DNA lesions, as well as epigenetically modified DNA. DNA polymerases produce mutation spectra in translesion DNA synthesis (TLS) through misincorporation of incorrect nucleotides, frameshift deletions, blockage of DNA replication, imbalance of leading- and lagging-strand DNA synthesis, and genome instability. Motif or subunit in DNA polymerases further affects the mutations in TLS. Moreover, protein interactions and accessory proteins in DNA replisome also alter mutations in TLS, demonstrated by several representative DNA replisomes. Finally, in cells, multiple DNA polymerases or cellular proteins collaborate in TLS and reduce in vivo mutagenesis. Summaries and perspectives were listed. This review shows mechanisms of mutagenesis induced by DNA lesions and the effects of multiple factors on mutations in TLS in vitro and in vivo.
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Affiliation(s)
- Huidong Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
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18
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Ghodke PP, Guengerich FP. Impact of 1, N 6-ethenoadenosine, a damaged ribonucleotide in DNA, on translesion synthesis and repair. J Biol Chem 2020; 295:6092-6107. [PMID: 32213600 DOI: 10.1074/jbc.ra120.012829] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/23/2020] [Indexed: 01/02/2023] Open
Abstract
Incorporation of ribonucleotides into DNA can severely diminish genome integrity. However, how ribonucleotides instigate DNA damage is poorly understood. In DNA, they can promote replication stress and genomic instability and have been implicated in several diseases. We report here the impact of the ribonucleotide rATP and of its naturally occurring damaged analog 1,N 6-ethenoadenosine (1,N 6-ϵrA) on translesion synthesis (TLS), mediated by human DNA polymerase η (hpol η), and on RNase H2-mediated incision. Mass spectral analysis revealed that 1,N 6-ϵrA in DNA generates extensive frameshifts during TLS, which can lead to genomic instability. Moreover, steady-state kinetic analysis of the TLS process indicated that deoxypurines (i.e. dATP and dGTP) are inserted predominantly opposite 1,N 6-ϵrA. We also show that hpol η acts as a reverse transcriptase in the presence of damaged ribonucleotide 1,N 6-ϵrA but has poor RNA primer extension activities. Steady-state kinetic analysis of reverse transcription and RNA primer extension showed that hpol η favors the addition of dATP and dGTP opposite 1,N 6-ϵrA. We also found that RNase H2 recognizes 1,N 6-ϵrA but has limited incision activity across from this lesion, which can lead to the persistence of this detrimental DNA adduct. We conclude that the damaged and unrepaired ribonucleotide 1,N 6-ϵrA in DNA exhibits mutagenic potential and can also alter the reading frame in an mRNA transcript because 1,N 6-ϵrA is incompletely incised by RNase H2.
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Affiliation(s)
- Pratibha P Ghodke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37323-0146
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37323-0146.
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19
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Franklin A, Steele EJ, Lindley RA. A proposed reverse transcription mechanism for (CAG)n and similar expandable repeats that cause neurological and other diseases. Heliyon 2020; 6:e03258. [PMID: 32140575 PMCID: PMC7044655 DOI: 10.1016/j.heliyon.2020.e03258] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 09/26/2019] [Accepted: 01/15/2020] [Indexed: 12/12/2022] Open
Abstract
The mechanism of (CAG)n repeat generation, and related expandable repeat diseases in non-dividing cells, is currently understood in terms of a DNA template-based DNA repair synthesis process involving hairpin stabilized slippage, local error-prone repair via MutSβ (MSH2-MSH3) hairpin protective stabilization, then nascent strand extension by DNA polymerases-β and -δ. We advance a very similar slipped hairpin-stabilized model involving MSH2-MSH3 with two key differences: the copying template may also be the nascent pre-mRNA with the repair pathway being mediated by the Y-family error-prone enzymes DNA polymerase-η and DNA polymerase-κ acting as reverse transcriptases. We argue that both DNA-based and RNA-based mechanisms could well be activated in affected non-dividing brain cells in vivo. Here, we compare the advantages of the RNA/RT-based model proposed by us as an adjunct to previously proposed models. In brief, our model depends upon dysregulated innate and adaptive immunity cascades involving AID/APOBEC and ADAR deaminases that are known to be involved in normal locus-specific immunoglobulin somatic hypermutation, cancer progression and somatic mutations at many off-target non-immunoglobulin sites across the genome: we explain how these processes could also play an active role in repeat expansion diseases at RNA polymerase II-transcribed genes.
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Affiliation(s)
- Andrew Franklin
- Medical Department, Novartis Pharmaceuticals UK Limited, 200 Frimley Business Park, Frimley, Surrey, GU16 7SR, United Kingdom
| | - Edward J. Steele
- Melville Analytics Pty Ltd, Melbourne, Vic, 3004, Australia
- CYO’Connor ERADE Village Foundation, Perth, WA, Australia
| | - Robyn A. Lindley
- GMDxgenomics, Melbourne, Vic, Australia
- Department of Clinical Pathology, Faculty of Medicine, Dentistry & Health Sciences, University of Melbourne, Vic, Australia
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20
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Du K, Zhang X, Zou Z, Li B, Gu S, Zhang S, Qu X, Ling Y, Zhang H. Epigenetically modified N 6-methyladenine inhibits DNA replication by human DNA polymerase η. DNA Repair (Amst) 2019; 78:81-90. [PMID: 30991231 DOI: 10.1016/j.dnarep.2019.03.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 01/06/2023]
Abstract
N6-methyladenine (6mA), as a newly reported epigenetic marker, plays significant roles in regulation of various biological processes in eukaryotes. However, the effect of 6mA on human DNA replication remain elusive. In this work, we used Y-family human DNA polymerase η as a model to investigate the kinetics of bypass of 6mA by hPol η. We found 6mA and its intermediate hypoxanthine (I) on template partially inhibited DNA replication by hPol η. dTMP incorporation opposite 6mA and dCMP incorporation opposite I can be considered as correct incorporation. However, both 6mA and I reduced correct incorporation efficiency, next-base extension efficiency, and the priority in extension beyond correct base pair. Both dTMP incorporation opposite 6mA and dCTP opposite I showed fast burst phases. However, 6mA and I reduced the burst incorporation rates (kpol) and increased the dissociation constant (Kd,dNTP), compared with that of dTMP incorporation opposite unmodified A. Biophysical binding assays revealed that both 6mA and I on template reduced the binding affinity of hPol η to DNA in binary or ternary complex compared with unmodified A. All the results explain the inhibition effects of 6mA and I on DNA replication by hPol η, providing new insight in the effects of epigenetically modified 6mA on human DNA replication.
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Affiliation(s)
- Ke Du
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China; Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiangqian Zhang
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China
| | - Zhenyu Zou
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Bianbian Li
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Shiling Gu
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Shuming Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiaoyi Qu
- College of Life Science, Yan´an University, Yan'an, Shaanxi, China
| | - Yihui Ling
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao Panyu District, Guangzhou, China
| | - Huidong Zhang
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China.
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21
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Pilzecker B, Jacobs H. Mutating for Good: DNA Damage Responses During Somatic Hypermutation. Front Immunol 2019; 10:438. [PMID: 30915081 PMCID: PMC6423074 DOI: 10.3389/fimmu.2019.00438] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/19/2019] [Indexed: 11/13/2022] Open
Abstract
Somatic hypermutation (SHM) of immunoglobulin (Ig) genes plays a key role in antibody mediated immunity. SHM in B cells provides the molecular basis for affinity maturation of antibodies. In this way SHM is key in optimizing antibody dependent immune responses. SHM is initiated by targeting the Activation-Induced Cytidine Deaminase (AID) to rearranged V(D)J and switch regions of Ig genes. The mutation rate of this programmed mutagenesis is ~10-3 base pairs per generation, a million-fold higher than the non-AID targeted genome of B cells. AID is a processive enzyme that binds single-stranded DNA and deaminates cytosines in DNA. Cytosine deamination generates highly mutagenic deoxy-uracil (U) in the DNA of both strands of the Ig loci. Mutagenic processing of the U by the DNA damage response generates the entire spectrum of base substitutions characterizing SHM at and around the initial U lesion. Starting from the U as a primary lesion, currently five mutagenic DNA damage response pathways have been identified in generating a well-defined SHM spectrum of C/G transitions, C/G transversions, and A/T mutations around this initial lesion. These pathways include (1) replication opposite template U generates transitions at C/G, (2) UNG2-dependent translesion synthesis (TLS) generates transversions at C/G, (3) a hybrid pathway comprising non-canonical mismatch repair (ncMMR) and UNG2-dependent TLS generates transversions at C/G, (4) ncMMR generates mutations at A/T, and (5) UNG2- and PCNA Ubiquitination (PCNA-Ub)-dependent mutations at A/T. Furthermore, specific strand-biases of SHM spectra arise as a consequence of a biased AID targeting, ncMMR, and anti-mutagenic repriming. Here, we review mammalian SHM with special focus on the mutagenic DNA damage response pathways involved in processing AID induced Us, the origin of characteristic strand biases, and relevance of the cell cycle.
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Affiliation(s)
| | - Heinz Jacobs
- Division of Tumor Biology & Immunology, The Netherlands Cancer Institute, Amsterdam, Netherlands
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22
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Su Y, Ghodke PP, Egli M, Li L, Wang Y, Guengerich FP. Human DNA polymerase η has reverse transcriptase activity in cellular environments. J Biol Chem 2019; 294:6073-6081. [PMID: 30842261 DOI: 10.1074/jbc.ra119.007925] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/04/2019] [Indexed: 12/24/2022] Open
Abstract
Classical DNA and RNA polymerase (pol) enzymes have defined roles with their respective substrates, but several pols have been found to have multiple functions. We reported previously that purified human DNA pol η (hpol η) can incorporate both deoxyribonucleoside triphosphates (dNTPs) and ribonucleoside triphosphates (rNTPs) and can use both DNA and RNA as substrates. X-ray crystal structures revealed that two pol η residues, Phe-18 and Tyr-92, behave as steric gates to influence sugar selectivity. However, the physiological relevance of these phenomena has not been established. Here, we show that purified hpol η adds rNTPs to DNA primers at physiological rNTP concentrations and in the presence of competing dNTPs. When two rATPs were inserted opposite a cyclobutane pyrimidine dimer, the substrate was less efficiently cleaved by human RNase H2. Human XP-V fibroblast extracts, devoid of hpol η, could not add rNTPs to a DNA primer, but the expression of transfected hpol η in the cells restored this ability. XP-V cell extracts did not add dNTPs to DNA primers hybridized to RNA, but could when hpol η was expressed in the cells. HEK293T cell extracts could add dNTPs to DNA primers hybridized to RNA, but lost this ability if hpol η was deleted. Interestingly, a similar phenomenon was not observed when other translesion synthesis (TLS) DNA polymerases-hpol ι, κ, or ζ-were individually deleted. These results suggest that hpol η is one of the major reverse transcriptases involved in physiological processes in human cells.
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Affiliation(s)
- Yan Su
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Pratibha P Ghodke
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Martin Egli
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | - Lin Li
- Department of Chemistry, University of California, Riverside, Riverside, California 92521
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, Riverside, California 92521
| | - F Peter Guengerich
- From the Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
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23
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Acharya N, Manohar K, Peroumal D, Khandagale P, Patel SK, Sahu SR, Kumari P. Multifaceted activities of DNA polymerase η: beyond translesion DNA synthesis. Curr Genet 2018; 65:649-656. [PMID: 30535880 DOI: 10.1007/s00294-018-0918-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 10/27/2022]
Abstract
DNA polymerases are evolved to extend the 3'-OH of a growing primer annealed to a template DNA substrate. Since replicative DNA polymerases have a limited role while replicating structurally distorted template, translesion DNA polymerases mostly from Y-family come to the rescue of stalled replication fork and maintain genome stability. DNA polymerase eta is one such specialized enzyme whose function is directly associated with casual development of certain skin cancers and chemo-resistance. More than 20 years of extensive studies are available to support TLS activities of Polη in bypassing various DNA lesions, in addition, limited but crucial growing evidence also exist to suggest Polη possessing TLS-independent cellular functions. In this review, we have mostly focused on non-TLS activities of Polη from different organisms including our recent findings from pathogenic yeast Candida albicans.
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Affiliation(s)
- Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India.
| | - Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
| | - Doureradjou Peroumal
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
| | - Prashant Khandagale
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
| | - Shraddheya Kumar Patel
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
| | - Satya Ranjan Sahu
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
| | - Premlata Kumari
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, 751023, India
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24
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Manohar K, Peroumal D, Acharya N. TLS dependent and independent functions of DNA polymerase eta (Polη/Rad30) from Pathogenic Yeast Candida albicans. Mol Microbiol 2018; 110:707-727. [PMID: 29907984 DOI: 10.1111/mmi.14004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 06/03/2018] [Accepted: 06/06/2018] [Indexed: 02/06/2023]
Abstract
Polη, a unique TLS DNA polymerase that promotes efficient bypass of UV-induced CPDs and cisplatin adducts, has not been explored in Candida species yet. Here, we show that CaPolη plays a vital role in protecting Candida albicans genome from diverse array of DNA damaging agents, not limited to UV and cisplatin. Polη deficient strain did not exhibit any hyphal development in the presence of UV and cisplatin while the wild type strain profusely developed DNA damage induced filamentation. The polarized growth induced by HU and MMS was found to be Polη independent. No common regulatory pathway of morphogenesis operates in C. albicans due to genomic stress, rather Polη branches away from RAD53 dependent pathway to be specific to UV/cisplatin. Interestingly, serum that does not inflict any DNA damage also induces hyphal growth in C. albicans, and requires a functionally active Polη. Importantly, deletion of RAD30 sensitized the strain to amphotericin B; but its presence resulted in azole drug tolerance only in DNA damaging conditions. We suggest that the roles of CaPolη in genome stability and genotoxins induced filamentation are due to its TLS activities; whereas its TLS independent functions play a vital role in serum induced morphogenesis and amphotericin B resistance.
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Affiliation(s)
- Kodavati Manohar
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Doureradjou Peroumal
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Narottam Acharya
- Laboratory of Genomic Instability and Diseases, Department of Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
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25
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Vaisman A, Woodgate R. Ribonucleotide discrimination by translesion synthesis DNA polymerases. Crit Rev Biochem Mol Biol 2018; 53:382-402. [PMID: 29972306 DOI: 10.1080/10409238.2018.1483889] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The well-being of all living organisms relies on the accurate duplication of their genomes. This is usually achieved by highly elaborate replicase complexes which ensure that this task is accomplished timely and efficiently. However, cells often must resort to the help of various additional "specialized" DNA polymerases that gain access to genomic DNA when replication fork progression is hindered. One such specialized polymerase family consists of the so-called "translesion synthesis" (TLS) polymerases; enzymes that have evolved to replicate damaged DNA. To fulfill their main cellular mission, TLS polymerases often must sacrifice precision when selecting nucleotide substrates. Low base-substitution fidelity is a well-documented inherent property of these enzymes. However, incorrect nucleotide substrates are not only those which do not comply with Watson-Crick base complementarity, but also those whose sugar moiety is incorrect. Does relaxed base-selectivity automatically mean that the TLS polymerases are unable to efficiently discriminate between ribonucleoside triphosphates and deoxyribonucleoside triphosphates that differ by only a single atom? Which strategies do TLS polymerases employ to select suitable nucleotide substrates? In this review, we will collate and summarize data accumulated over the past decade from biochemical and structural studies, which aim to answer these questions.
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Affiliation(s)
- Alexandra Vaisman
- a Laboratory of Genomic Integrity , National Institute of Child Health and Human Development, National Institutes of Health , Bethesda , MD , USA
| | - Roger Woodgate
- a Laboratory of Genomic Integrity , National Institute of Child Health and Human Development, National Institutes of Health , Bethesda , MD , USA
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26
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Genna V, Carloni P, De Vivo M. A Strategically Located Arg/Lys Residue Promotes Correct Base Paring During Nucleic Acid Biosynthesis in Polymerases. J Am Chem Soc 2018; 140:3312-3321. [PMID: 29424536 DOI: 10.1021/jacs.7b12446] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Polymerases (Pols) synthesize the double-stranded nucleic acids in the Watson-Crick (W-C) conformation, which is critical for DNA and RNA functioning. Yet, the molecular basis to catalyze the W-C base pairing during Pol-mediated nucleic acids biosynthesis remains unclear. Here, through bioinformatics analyses on a large data set of Pol/DNA structures, we first describe the conserved presence of one positively charged residue (Lys or Arg), which is similarly located near the enzymatic two-metal active site, always interacting directly with the incoming substrate (d)NTP. Incidentally, we noted that some Pol/DNA structures showing the alternative Hoogsteen base pairing were often solved with this specific residue either mutated, displaced, or missing. We then used quantum and classical simulations coupled to free-energy calculations to illustrate how, in human DNA Pol-η, the conserved Arg61 favors W-C base pairing through defined interactions with the incoming nucleotide. Taken together, these structural observations and computational results suggest a structural framework in which this specific residue is critical for stabilizing the incoming (d)NTP nucleotide and base pairing during Pol-mediated nucleic acid biosynthesis. These results may benefit enzyme engineering for nucleic acid processing and encourage new drug discovery strategies to modulate Pols function.
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Affiliation(s)
- Vito Genna
- Laboratory of Molecular Modeling and Drug Discovery , Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genoa , Italy.,Computational Biophysics, German Research School for Simulation Sciences, and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Institute of Neuroscience and Medicine INM-9 , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Paolo Carloni
- Computational Biophysics, German Research School for Simulation Sciences, and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Institute of Neuroscience and Medicine INM-9 , Forschungszentrum Jülich , 52425 Jülich , Germany
| | - Marco De Vivo
- Laboratory of Molecular Modeling and Drug Discovery , Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genoa , Italy.,Computational Biophysics, German Research School for Simulation Sciences, and Computational Biomedicine, Institute for Advanced Simulation IAS-5 and Institute of Neuroscience and Medicine INM-9 , Forschungszentrum Jülich , 52425 Jülich , Germany
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