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Łazowski K, Woodgate R, Fijalkowska IJ. Escherichia coli DNA replication: the old model organism still holds many surprises. FEMS Microbiol Rev 2024; 48:fuae018. [PMID: 38982189 PMCID: PMC11253446 DOI: 10.1093/femsre/fuae018] [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: 05/09/2024] [Revised: 06/26/2024] [Accepted: 07/08/2024] [Indexed: 07/11/2024] Open
Abstract
Research on Escherichia coli DNA replication paved the groundwork for many breakthrough discoveries with important implications for our understanding of human molecular biology, due to the high level of conservation of key molecular processes involved. To this day, it attracts a lot of attention, partially by virtue of being an important model organism, but also because the understanding of factors influencing replication fidelity might be important for studies on the emergence of antibiotic resistance. Importantly, the wide access to high-resolution single-molecule and live-cell imaging, whole genome sequencing, and cryo-electron microscopy techniques, which were greatly popularized in the last decade, allows us to revisit certain assumptions about the replisomes and offers very detailed insight into how they work. For many parts of the replisome, step-by-step mechanisms have been reconstituted, and some new players identified. This review summarizes the latest developments in the area, focusing on (a) the structure of the replisome and mechanisms of action of its components, (b) organization of replisome transactions and repair, (c) replisome dynamics, and (d) factors influencing the base and sugar fidelity of DNA synthesis.
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Affiliation(s)
- Krystian Łazowski
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, United States
| | - Iwona J Fijalkowska
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
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2
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Yang J, Sun M, Ran Z, Yang T, Kundnani DL, Storici F, Xu P. rNMPID: a database for riboNucleoside MonoPhosphates in DNA. BIOINFORMATICS ADVANCES 2024; 4:vbae063. [PMID: 38736683 PMCID: PMC11088741 DOI: 10.1093/bioadv/vbae063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/27/2024] [Accepted: 05/07/2024] [Indexed: 05/14/2024]
Abstract
Motivation Ribonucleoside monophosphates (rNMPs) are the most abundant non-standard nucleotides embedded in genomic DNA. If the presence of rNMP in DNA cannot be controlled, it can lead to genome instability. The actual regulatory functions of rNMPs in DNA remain mainly unknown. Considering the association between rNMP embedment and various diseases and cancer, the phenomenon of rNMP embedment in DNA has become a prominent area of research in recent years. Results We introduce the rNMPID database, which is the first database revealing rNMP-embedment characteristics, strand bias, and preferred incorporation patterns in the genomic DNA of samples from bacterial to human cells of different genetic backgrounds. The rNMPID database uses datasets generated by different rNMP-mapping techniques. It provides the researchers with a solid foundation to explore the features of rNMP embedded in the genomic DNA of multiple sources, and their association with cellular functions, and, in future, disease. It also significantly benefits researchers in the fields of genetics and genomics who aim to integrate their studies with the rNMP-embedment data. Availability and implementation rNMPID is freely accessible on the web at https://www.rnmpid.org.
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Affiliation(s)
- Jingcheng Yang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Human Phenome Institute, and Shanghai Cancer Center, Fudan University, Shanghai 200438, China
- Greater Bay Area Institute of Precision Medicine, Guangzhou, Guangdong 511462, China
| | - Mo Sun
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Zihan Ran
- Department of Research, Shanghai University of Medicine & Health Sciences Affiliated Zhoupu Hospital, Shanghai 201318, China
- Inspection and Quarantine Department, The College of Medical Technology, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China
| | - Taehwan Yang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Deepali L Kundnani
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Francesca Storici
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Penghao Xu
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States
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3
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Gulkis M, Martinez E, Almohdar D, Çağlayan M. Unfilled gaps by polβ lead to aberrant ligation by LIG1 at the downstream steps of base excision repair pathway. Nucleic Acids Res 2024; 52:3810-3822. [PMID: 38366780 DOI: 10.1093/nar/gkae104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 01/11/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
Base excision repair (BER) involves the tightly coordinated function of DNA polymerase β (polβ) and DNA ligase I (LIG1) at the downstream steps. Our previous studies emphasize that defective substrate-product channeling, from gap filling by polβ to nick sealing by LIG1, can lead to interruptions in repair pathway coordination. Yet, the molecular determinants that dictate accurate BER remains largely unknown. Here, we demonstrate that a lack of gap filling by polβ leads to faulty repair events and the formation of deleterious DNA intermediates. We dissect how ribonucleotide challenge and cancer-associated mutations could adversely impact the ability of polβ to efficiently fill the one nucleotide gap repair intermediate which subsequently results in gap ligation by LIG1, leading to the formation of single-nucleotide deletion products. Moreover, we demonstrate that LIG1 is not capable of discriminating against nick DNA containing a 3'-ribonucleotide, regardless of base-pairing potential or damage. Finally, AP-Endonuclease 1 (APE1) shows distinct substrate specificity for the exonuclease removal of 3'-mismatched bases and ribonucleotides from nick repair intermediate. Overall, our results reveal that unfilled gaps result in impaired coordination between polβ and LIG1, defining a possible type of mutagenic event at the downstream steps where APE1 could provide a proofreading role to maintain BER efficiency.
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Affiliation(s)
- Mitchell Gulkis
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Ernesto Martinez
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Danah Almohdar
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Melike Çağlayan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
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4
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Wurihan W, Wang Y, Yeung S, Zou Y, Lai Z, Fondell JD, Li WV, Zhong G, Fan H. Expression activation of over 70% of Chlamydia trachomatis genes during the first hour of infection. Infect Immun 2024; 92:e0053923. [PMID: 38299827 PMCID: PMC10929459 DOI: 10.1128/iai.00539-23] [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: 01/02/2024] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
The obligate intracellular bacterium Chlamydia has a unique developmental cycle that alternates between two contrasting cell types. With a hardy envelope and highly condensed genome, the small elementary body (EB) maintains limited metabolic activities yet survives in extracellular environments and is infectious. After entering host cells, EBs differentiate into larger and proliferating reticulate bodies (RBs). Progeny EBs are derived from RBs in late developmental stages and eventually exit host cells. How expression of the chlamydial genome consisting of nearly 1,000 genes governs the chlamydial developmental cycle is unclear. A previous microarray study identified only 29 Chlamydia trachomatis immediate early genes, defined as genes with increased expression during the first hour postinoculation in cultured cells. In this study, we performed more sensitive RNA sequencing (RNA-Seq) analysis for C. trachomatis cultures with high multiplicities of infection. Remarkably, we observed well over 700 C. trachomatis genes that underwent 2- to 900-fold activation within 1 hour postinoculation. Quantitative reverse transcription real-time PCR analysis was further used to validate the activated expression of a large subset of the genes identified by RNA-Seq. Importantly, our results demonstrate that the immediate early transcriptome is over 20 times more extensive than previously realized. Gene ontology analysis indicates that the activated expression spans all functional categories. We conclude that over 70% of C. trachomatis genes are activated in EBs almost immediately upon entry into host cells, thus implicating their importance in initiating rapid differentiation into RBs and establishing an intracellular niche conducive with chlamydial development and growth.
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Affiliation(s)
- Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Yuxuan Wang
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Sydney Yeung
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Yi Zou
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, Texas, USA
- Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Joseph D. Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Wei Vivian Li
- Department of Statistics, University of California Riverside, Riverside, California, USA
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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5
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Xu P, Yang T, Kundnani DL, Sun M, Marsili S, Gombolay A, Jeon Y, Newnam G, Balachander S, Bazzani V, Baccarani U, Park V, Tao S, Lori A, Schinazi R, Kim B, Pursell Z, Tell G, Vascotto C, Storici F. Light-strand bias and enriched zones of embedded ribonucleotides are associated with DNA replication and transcription in the human-mitochondrial genome. Nucleic Acids Res 2024; 52:1207-1225. [PMID: 38117983 PMCID: PMC10853789 DOI: 10.1093/nar/gkad1204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/30/2023] [Accepted: 12/05/2023] [Indexed: 12/22/2023] Open
Abstract
Abundant ribonucleoside-triphosphate (rNTP) incorporation into DNA by DNA polymerases in the form of ribonucleoside monophosphates (rNMPs) is a widespread phenomenon in nature, resulting in DNA-structural change and genome instability. The rNMP distribution, characteristics, hotspots and association with DNA metabolic processes in human mitochondrial DNA (hmtDNA) remain mostly unknown. Here, we utilize the ribose-seq technique to capture embedded rNMPs in hmtDNA of six different cell types. In most cell types, the rNMPs are preferentially embedded on the light strand of hmtDNA with a strong bias towards rCMPs; while in the liver-tissue cells, the rNMPs are predominately found on the heavy strand. We uncover common rNMP hotspots and conserved rNMP-enriched zones across the entire hmtDNA, including in the control region, which links the rNMP presence to the frequent hmtDNA replication-failure events. We show a strong correlation between coding-sequence size and rNMP-embedment frequency per nucleotide on the non-template, light strand in all cell types, supporting the presence of transient RNA-DNA hybrids preceding light-strand replication. Moreover, we detect rNMP-embedment patterns that are only partly conserved across the different cell types and are distinct from those found in yeast mtDNA. The study opens new research directions to understand the biology of hmtDNA and genomic rNMPs.
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Affiliation(s)
- Penghao Xu
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Taehwan Yang
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Deepali L Kundnani
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Mo Sun
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Stefania Marsili
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Alli L Gombolay
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Youngkyu Jeon
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Gary Newnam
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Sathya Balachander
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Veronica Bazzani
- Department of Medicine, University of Udine, Udine 33100, Italy
- IMol Polish Academy of Sciences, Warsaw 02-247, Poland
| | - Umberto Baccarani
- Department of Medicine, University of Udine, Udine 33100, Italy
- General Surgery Clinic and Liver Transplant Center, University-Hospital of Udine, Udine 33100, Italy
| | - Vivian S Park
- Department of Biochemistry and Molecular Biology, Tulane Cancer Center, Tulane University of Medicine, New Orleans, LA 70118, USA
| | - Sijia Tao
- Center for ViroScience and Cure, Department of Pediatrics, Laboratory of Biochemical Pharmacology, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta 30322, GA, USA
| | - Adriana Lori
- Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta 30329, GA, USA
- Department of Population Science, American Cancer Society, Kennesaw 30144, GA, USA
| | - Raymond F Schinazi
- Center for ViroScience and Cure, Department of Pediatrics, Laboratory of Biochemical Pharmacology, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta 30322, GA, USA
| | - Baek Kim
- Center for ViroScience and Cure, Department of Pediatrics, Laboratory of Biochemical Pharmacology, Emory University School of Medicine and Children’s Healthcare of Atlanta, Atlanta 30322, GA, USA
| | - Zachary F Pursell
- Department of Biochemistry and Molecular Biology, Tulane Cancer Center, Tulane University of Medicine, New Orleans, LA 70118, USA
| | - Gianluca Tell
- Laboratory of Molecular Biology and DNA Repair, Department of Medicine, University of Udine, Udine 33100, Italy
| | - Carlo Vascotto
- Department of Medicine, University of Udine, Udine 33100, Italy
- IMol Polish Academy of Sciences, Warsaw 02-247, Poland
| | - Francesca Storici
- School of Biological Sciences, Georgia Institute of Technology, Atlanta 30332, GA, USA
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6
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Tripathi D, Oldenburg DJ, Bendich AJ. Ribonucleotide and R-Loop Damage in Plastid DNA and Mitochondrial DNA during Maize Development. PLANTS (BASEL, SWITZERLAND) 2023; 12:3161. [PMID: 37687407 PMCID: PMC10489836 DOI: 10.3390/plants12173161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023]
Abstract
Although the temporary presence of ribonucleotides in DNA is normal, their persistence represents a form of DNA damage. Here, we assess such damage and damage defense to DNA in plastids and mitochondria of maize. Shoot development proceeds from meristematic, non-pigmented cells containing proplastids and promitochondria at the leaf base to non-dividing green cells in the leaf blade containing mature organelles. The organellar DNAs (orgDNAs) become fragmented during this transition. Previously, orgDNA damage and damage defense of two types, oxidative and glycation, was described in maize, and now a third type, ribonucleotide damage, is reported. We hypothesized that ribonucleotide damage changes during leaf development and could contribute to the demise of orgDNAs. The levels of ribonucleotides and R-loops in orgDNAs and of RNase H proteins in organelles were measured throughout leaf development and in leaves grown in light and dark conditions. The data reveal that ribonucleotide damage to orgDNAs increased by about 2- to 5-fold during normal maize development from basal meristem to green leaf and when leaves were grown in normal light conditions compared to in the dark. During this developmental transition, the levels of the major agent of defense, RNase H, declined. The decline in organellar genome integrity during maize development may be attributed to oxidative, glycation, and ribonucleotide damages that are not repaired.
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Affiliation(s)
| | | | - Arnold J. Bendich
- Department of Biology, University of Washington, Seattle, WA 98195, USA; (D.T.); (D.J.O.)
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7
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Dressel N, Natusch L, Munz CM, Costas Ramon S, Morcos MNF, Loff A, Hiller B, Haase C, Schulze L, Müller P, Lesche M, Dahl A, Luksch H, Rösen-Wolff A, Roers A, Behrendt R, Gerbaulet A. Activation of the cGAS/STING Axis in Genome-Damaged Hematopoietic Cells Does Not Impact Blood Cell Formation or Leukemogenesis. Cancer Res 2023; 83:2858-2872. [PMID: 37335136 DOI: 10.1158/0008-5472.can-22-3860] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 05/04/2023] [Accepted: 06/14/2023] [Indexed: 06/21/2023]
Abstract
Genome damage is a main driver of malignant transformation, but it also induces aberrant inflammation via the cGAS/STING DNA-sensing pathway. Activation of cGAS/STING can trigger cell death and senescence, thereby potentially eliminating genome-damaged cells and preventing against malignant transformation. Here, we report that defective ribonucleotide excision repair (RER) in the hematopoietic system caused genome instability with concomitant activation of the cGAS/STING axis and compromised hematopoietic stem cell function, ultimately resulting in leukemogenesis. Additional inactivation of cGAS, STING, or type I IFN signaling, however, had no detectable effect on blood cell generation and leukemia development in RER-deficient hematopoietic cells. In wild-type mice, hematopoiesis under steady-state conditions and in response to genome damage was not affected by loss of cGAS. Together, these data challenge a role of the cGAS/STING pathway in protecting the hematopoietic system against DNA damage and leukemic transformation. SIGNIFICANCE Loss of cGAS/STING signaling does not impact DNA damage-driven leukemogenesis or alter steady-state, perturbed or malignant hematopoiesis, indicating that the cGAS/STING axis is not a crucial antioncogenic mechanism in the hematopoietic system. See related commentary by Zierhut, p. 2807.
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Affiliation(s)
- Nicole Dressel
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Loreen Natusch
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Clara M Munz
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | | | - Mina N F Morcos
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Anja Loff
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Björn Hiller
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Christa Haase
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Livia Schulze
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
| | - Patrick Müller
- Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Mathias Lesche
- DRESDEN-concept Genome Center, Center for Molecular and Cellular Bioengineering, TU Dresden, Dresden, Germany
| | - Andreas Dahl
- DRESDEN-concept Genome Center, Center for Molecular and Cellular Bioengineering, TU Dresden, Dresden, Germany
| | - Hella Luksch
- Department of Pediatrics, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Angela Rösen-Wolff
- Department of Pediatrics, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Axel Roers
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
- Institute for Immunology, Heidelberg University Hospital, Heidelberg, Germany
| | - Rayk Behrendt
- Institute for Immunology, Faculty of Medicine, TU Dresden, Dresden, Germany
- Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
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8
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Łazowski K, Faraz M, Vaisman A, Ashton NW, Jonczyk P, Fijalkowska IJ, Clausen AR, Woodgate R, Makiela-Dzbenska K. Strand specificity of ribonucleotide excision repair in Escherichia coli. Nucleic Acids Res 2023; 51:1766-1782. [PMID: 36762476 PMCID: PMC9976901 DOI: 10.1093/nar/gkad038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/03/2023] [Accepted: 01/12/2023] [Indexed: 02/11/2023] Open
Abstract
In Escherichia coli, replication of both strands of genomic DNA is carried out by a single replicase-DNA polymerase III holoenzyme (pol III HE). However, in certain genetic backgrounds, the low-fidelity TLS polymerase, DNA polymerase V (pol V) gains access to undamaged genomic DNA where it promotes elevated levels of spontaneous mutagenesis preferentially on the lagging strand. We employed active site mutants of pol III (pol IIIα_S759N) and pol V (pol V_Y11A) to analyze ribonucleotide incorporation and removal from the E. coli chromosome on a genome-wide scale under conditions of normal replication, as well as SOS induction. Using a variety of methods tuned to the specific properties of these polymerases (analysis of lacI mutational spectra, lacZ reversion assay, HydEn-seq, alkaline gel electrophoresis), we present evidence that repair of ribonucleotides from both DNA strands in E. coli is unequal. While RNase HII plays a primary role in leading-strand Ribonucleotide Excision Repair (RER), the lagging strand is subject to other repair systems (RNase HI and under conditions of SOS activation also Nucleotide Excision Repair). Importantly, we suggest that RNase HI activity can also influence the repair of single ribonucleotides incorporated by the replicase pol III HE into the lagging strand.
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Affiliation(s)
- Krystian Łazowski
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Mahmood Faraz
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg 40530, Sweden
| | - Alexandra Vaisman
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA
| | - Nicholas W Ashton
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA
| | - Piotr Jonczyk
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Iwona J Fijalkowska
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
| | - Anders R Clausen
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg 40530, Sweden
| | - Roger Woodgate
- Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3371, USA
| | - Karolina Makiela-Dzbenska
- Laboratory of DNA Replication and Genome Stability, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland
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9
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Kandabashi M, Yano H, Hara H, Ogawa S, Kamoda K, Ishibashi S, Himeda K, Baba M, Takita T, Yasukawa K. Analysis of ribonucleotide content in the genomic DNA of ribonuclease H2 A subunit (RH2A)-knockout NIH3T3 cells after transient expression of wild-type RH2A or RH2A variants with an Aicardi-Goutières syndrome-causing mutation. J Biochem 2022; 172:225-231. [DOI: 10.1093/jb/mvac056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 07/03/2022] [Indexed: 11/13/2022] Open
Abstract
Summary
Ribonuclease (RNase) H2 is involved in the removal of ribonucleotides embedded in genomic DNA. Eukaryotic RNase H2 is a heterotrimer consisting of the catalytic A subunit (RH2A) and the accessory B and C subunits. This study aimed to compare the cellular activities of wild-type ribonuclease (RNase) H2 and its variants with a mutation causing neuroinflammatory autoimmune disease, Aicardi-Goutières syndrome (AGS). We first analyzed cellular RNase H2 activity and ribonucleotide content in the genomic DNA of RH2A-knockout (KO) mouse fibroblast NIH3T3 cells after transfection with a transient expression plasmid encoding mouse wild-type RH2A. From four hours after transfection, the RNase H2 activity increased, and the amount of ribonucleotides decreased, as compared with the corresponding non-transfected RH2A-KO cells. This demonstrated the rapidness of ribonucleotide turnover in mammalian genomic DNA and the importance of continuous expression of RNase H2 to maintain the ribonucleotide amount low. Next, we expressed mouse RH2A variants with a mutation corresponding to a human AGS-causing mutation in RH2A-KO NIH3T3 cells. Neither increase in RNase H2 activity nor decrease in ribonucleotide amount were observed for G37S; however, both conditions were observed for N213I and R293H. This corresponded with our previous results on the activity of recombinant human RNase H2 variants.
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Affiliation(s)
- Mako Kandabashi
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Haruna Yano
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Haruka Hara
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Saori Ogawa
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kana Kamoda
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shu Ishibashi
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kohei Himeda
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Misato Baba
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Teisuke Takita
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kiyoshi Yasukawa
- Graduate School of Agriculture Division of Food Science and Biotechnology, , Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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10
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Carvalho G, Repolês BM, Mendes I, Wanrooij PH. Mitochondrial DNA Instability in Mammalian Cells. Antioxid Redox Signal 2022; 36:885-905. [PMID: 34015960 PMCID: PMC9127837 DOI: 10.1089/ars.2021.0091] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 02/06/2023]
Abstract
Significance: The small, multicopy mitochondrial genome (mitochondrial DNA [mtDNA]) is essential for efficient energy production, as alterations in its coding information or a decrease in its copy number disrupt mitochondrial ATP synthesis. However, the mitochondrial replication machinery encounters numerous challenges that may limit its ability to duplicate this important genome and that jeopardize mtDNA stability, including various lesions in the DNA template, topological stress, and an insufficient nucleotide supply. Recent Advances: An ever-growing array of DNA repair or maintenance factors are being reported to localize to the mitochondria. We review current knowledge regarding the mitochondrial factors that may contribute to the tolerance or repair of various types of changes in the mitochondrial genome, such as base damage, incorporated ribonucleotides, and strand breaks. We also discuss the newly discovered link between mtDNA instability and activation of the innate immune response. Critical Issues: By which mechanisms do mitochondria respond to challenges that threaten mtDNA maintenance? What types of mtDNA damage are repaired, and when are the affected molecules degraded instead? And, finally, which forms of mtDNA instability trigger an immune response, and how? Future Directions: Further work is required to understand the contribution of the DNA repair and damage-tolerance factors present in the mitochondrial compartment, as well as the balance between mtDNA repair and degradation. Finally, efforts to understand the events underlying mtDNA release into the cytosol are warranted. Pursuing these and many related avenues can improve our understanding of what goes wrong in mitochondrial disease. Antioxid. Redox Signal. 36, 885-905.
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Affiliation(s)
- Gustavo Carvalho
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Bruno Marçal Repolês
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Isabela Mendes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Paulina H. Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
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11
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Williams JS, Kunkel TA. Ribonucleotide Incorporation by Eukaryotic B-family Replicases and Its Implications for Genome Stability. Annu Rev Biochem 2022; 91:133-155. [PMID: 35287470 DOI: 10.1146/annurev-biochem-032620-110354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our current view of how DNA-based genomes are efficiently and accurately replicated continues to evolve as new details emerge on the presence of ribonucleotides in DNA. Ribonucleotides are incorporated during eukaryotic DNA replication at rates that make them the most common noncanonical nucleotide placed into the nuclear genome, they are efficiently repaired, and their removal impacts genome integrity. This review focuses on three aspects of this subject: the incorporation of ribonucleotides into the eukaryotic nuclear genome during replication by B-family DNA replicases, how these ribonucleotides are removed, and the consequences of their presence or removal for genome stability and disease. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Jessica S Williams
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA;
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA;
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12
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Vanoevelen JM, Bierau J, Grashorn JC, Lambrichs E, Kamsteeg EJ, Bok LA, Wevers RA, van der Knaap MS, Bugiani M, Frisk JH, Colnaghi R, O'Driscoll M, Hellebrekers DMEI, Rodenburg R, Ferreira CR, Brunner HG, van den Wijngaard A, Abdel-Salam GMH, Wang L, Stumpel CTRM. DTYMK is essential for genome integrity and neuronal survival. Acta Neuropathol 2022; 143:245-262. [PMID: 34918187 PMCID: PMC8742820 DOI: 10.1007/s00401-021-02394-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 12/03/2021] [Accepted: 12/03/2021] [Indexed: 11/28/2022]
Abstract
Nucleotide metabolism is a complex pathway regulating crucial cellular processes such as nucleic acid synthesis, DNA repair and proliferation. This study shows that impairment of the biosynthesis of one of the building blocks of DNA, dTTP, causes a severe, early-onset neurodegenerative disease. Here, we describe two unrelated children with bi-allelic variants in DTYMK, encoding dTMPK, which catalyzes the penultimate step in dTTP biosynthesis. The affected children show severe microcephaly and growth retardation with minimal neurodevelopment. Brain imaging revealed severe cerebral atrophy and disappearance of the basal ganglia. In cells of affected individuals, dTMPK enzyme activity was minimal, along with impaired DNA replication. In addition, we generated dtymk mutant zebrafish that replicate this phenotype of microcephaly, neuronal cell death and early lethality. An increase of ribonucleotide incorporation in the genome as well as impaired responses to DNA damage were observed in dtymk mutant zebrafish, providing novel pathophysiological insights. It is highly remarkable that this deficiency is viable as an essential component for DNA cannot be generated, since the metabolic pathway for dTTP synthesis is completely blocked. In summary, by combining genetic and biochemical approaches in multiple models we identified loss-of-function of DTYMK as the cause of a severe postnatal neurodegenerative disease and highlight the essential nature of dTTP synthesis in the maintenance of genome stability and neuronal survival.
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Affiliation(s)
- Jo M Vanoevelen
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands.
- GROW-School for Oncology and Developmental Biology, 6229 ER, Maastricht, The Netherlands.
| | - Jörgen Bierau
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
| | - Janine C Grashorn
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
| | - Ellen Lambrichs
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud UMC, 6525 GA, Nijmegen, The Netherlands
| | - Levinus A Bok
- Department of Pediatrics, Màxima Medical Center, 5504 DB, Veldhoven, The Netherlands
| | - Ron A Wevers
- Translational Metabolic Laboratory, Radboud UMC, 6525 GA, Nijmegen, The Netherlands
| | | | - Marianna Bugiani
- Department of Neuropathology, VUMC, 1105 AZ, Amsterdam, The Netherlands
| | - Junmei Hu Frisk
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Rita Colnaghi
- Genome Damage and Stability Centre, University of Sussex, Brighton, BN1 9RH, UK
| | - Mark O'Driscoll
- Genome Damage and Stability Centre, University of Sussex, Brighton, BN1 9RH, UK
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
| | - Richard Rodenburg
- Translational Metabolic Laboratory, Radboud UMC, 6525 GA, Nijmegen, The Netherlands
| | - Carlos R Ferreira
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Han G Brunner
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
- Department of Human Genetics, Radboud UMC, 6525 GA, Nijmegen, The Netherlands
- GROW-School for Oncology and Developmental Biology, 6229 ER, Maastricht, The Netherlands
- MHENS School of Neuroscience, 6229 ER, Maastricht, The Netherlands
- Donders Institute of Neuroscience, Radboud UMC, 6525 GA, Nijmegen, The Netherlands
| | - Arthur van den Wijngaard
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands
| | - Ghada M H Abdel-Salam
- Department of Clinical Genetics, Human Genetics and Genome Research Division, National Research Centre, Cairo, 12311, Egypt
| | - Liya Wang
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden
| | - Constance T R M Stumpel
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 ER, Maastricht, The Netherlands.
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13
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Chen YX, Tan LM, Gong JP, Huang MS, Yin JY, Zhang W, Zhou HH, Liu ZQ. Response prediction biomarkers and drug combinations of PARP inhibitors in prostate cancer. Acta Pharmacol Sin 2021; 42:1970-1980. [PMID: 33589795 PMCID: PMC8632930 DOI: 10.1038/s41401-020-00604-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 12/20/2020] [Indexed: 01/31/2023] Open
Abstract
PARP inhibitors are a group of inhibitors targeting poly(ADP-ribose) polymerases (PARP1 or PARP2) involved in DNA repair and transcriptional regulation, which may induce synthetic lethality in BRCAness tumors. Systematic analyzes of genomic sequencing in prostate cancer show that ~10%-19% of patients with primary prostate cancer have inactivated DNA repair genes, with a notably higher proportion of 23%-27% in patients with metastatic castration-resistant prostate cancer (mCRPC). These characteristic genomic alterations confer possible vulnerability to PARP inhibitors in patients with mCRPC who benefit only modestly from other therapies. However, only a small proportion of patients with mCRPC shows sensitivity to PARP inhibitors, and these sensitive patients cannot be fully identified by existing response prediction biomarkers. In this review, we provide an overview of the potential response prediction biomarkers and synergistic combinations studied in the preclinical and clinical stages, which may expand the population of patients with prostate cancer who may benefit from PARP inhibitors.
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Affiliation(s)
- Yi-Xin Chen
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China
| | - Li-Ming Tan
- Department of Pharmacy, The Second People's Hospital of Huaihua City, Huaihua, 418000, China
| | - Jian-Ping Gong
- Department of Pharmacy, The Second People's Hospital of Huaihua City, Huaihua, 418000, China
| | - Ma-Sha Huang
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China
| | - Ji-Ye Yin
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China
| | - Wei Zhang
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China
| | - Hong-Hao Zhou
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China
| | - Zhao-Qian Liu
- Department of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, and National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, China.
- Institute of Clinical Pharmacology, Engineering Research Center for Applied Technology of Pharmacogenomics of Ministry of Education, Central South University, Changsha, 410078, China.
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14
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A DOT1B/Ribonuclease H2 Protein Complex Is Involved in R-Loop Processing, Genomic Integrity, and Antigenic Variation in Trypanosoma brucei. mBio 2021; 12:e0135221. [PMID: 34749530 PMCID: PMC8576533 DOI: 10.1128/mbio.01352-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The parasite Trypanosoma brucei periodically changes the expression of protective variant surface glycoproteins (VSGs) to evade its host’s immune system in a process known as antigenic variation. One route to change VSG expression is the transcriptional activation of a previously silent VSG expression site (ES), a subtelomeric region containing the VSG genes. Homologous recombination of a different VSG from a large reservoir into the active ES represents another route. The conserved histone methyltransferase DOT1B is involved in transcriptional silencing of inactive ES and influences ES switching kinetics. The molecular machinery that enables DOT1B to execute these regulatory functions remains elusive, however. To better understand DOT1B-mediated regulatory processes, we purified DOT1B-associated proteins using complementary biochemical approaches. We identified several novel DOT1B interactors. One of these was the RNase H2 complex, previously shown to resolve RNA-DNA hybrids, maintain genome integrity, and play a role in antigenic variation. Our study revealed that DOT1B depletion results in an increase in RNA-DNA hybrids, accumulation of DNA damage, and ES switching events. Surprisingly, a similar pattern of VSG deregulation was observed in RNase H2 mutants. We propose that both proteins act together in resolving R-loops to ensure genome integrity and contribute to the tightly regulated process of antigenic variation.
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15
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Kwok M, Agathanggelou A, Davies N, Stankovic T. Targeting the p53 Pathway in CLL: State of the Art and Future Perspectives. Cancers (Basel) 2021; 13:4681. [PMID: 34572908 PMCID: PMC8468925 DOI: 10.3390/cancers13184681] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/16/2021] [Accepted: 09/16/2021] [Indexed: 12/20/2022] Open
Abstract
The p53 pathway is a desirable therapeutic target, owing to its critical role in the maintenance of genome integrity. This is exemplified in chronic lymphocytic leukemia (CLL), one of the most common adult hematologic malignancies, in which functional loss of p53 arising from genomic aberrations are frequently associated with clonal evolution, disease progression, and therapeutic resistance, even in the contemporary era of CLL targeted therapy and immunotherapy. Targeting the 'undruggable' p53 pathway therefore arguably represents the holy grail of cancer research. In recent years, several strategies have been proposed to exploit p53 pathway defects for cancer treatment. Such strategies include upregulating wild-type p53, restoring tumor suppressive function in mutant p53, inducing synthetic lethality by targeting collateral genome maintenance pathways, and harnessing the immunogenicity of p53 pathway aberrations. In this review, we will examine the biological and clinical implications of p53 pathway defects, as well as our progress towards development of therapeutic approaches targeting the p53 pathway, specifically within the context of CLL. We will appraise the opportunities and pitfalls associated with these therapeutic strategies, and evaluate their place amongst the array of new biological therapies for CLL.
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Affiliation(s)
- Marwan Kwok
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2SY, UK; (A.A.); (N.D.)
- Centre for Clinical Haematology, Queen Elizabeth Hospital Birmingham, Birmingham B15 2SY, UK
| | - Angelo Agathanggelou
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2SY, UK; (A.A.); (N.D.)
| | - Nicholas Davies
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2SY, UK; (A.A.); (N.D.)
| | - Tatjana Stankovic
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2SY, UK; (A.A.); (N.D.)
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16
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Replication Stress, Genomic Instability, and Replication Timing: A Complex Relationship. Int J Mol Sci 2021; 22:ijms22094764. [PMID: 33946274 PMCID: PMC8125245 DOI: 10.3390/ijms22094764] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/29/2022] Open
Abstract
The replication-timing program constitutes a key element of the organization and coordination of numerous nuclear processes in eukaryotes. This program is established at a crucial moment in the cell cycle and occurs simultaneously with the organization of the genome, thus indicating the vital significance of this process. With recent technological achievements of high-throughput approaches, a very strong link has been confirmed between replication timing, transcriptional activity, the epigenetic and mutational landscape, and the 3D organization of the genome. There is also a clear relationship between replication stress, replication timing, and genomic instability, but the extent to which they are mutually linked to each other is unclear. Recent evidence has shown that replication timing is affected in cancer cells, although the cause and consequence of this effect remain unknown. However, in-depth studies remain to be performed to characterize the molecular mechanisms of replication-timing regulation and clearly identify different cis- and trans-acting factors. The results of these studies will potentially facilitate the discovery of new therapeutic pathways, particularly for personalized medicine, or new biomarkers. This review focuses on the complex relationship between replication timing, replication stress, and genomic instability.
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17
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Kim SC, O'Flaherty DK, Giurgiu C, Zhou L, Szostak JW. The Emergence of RNA from the Heterogeneous Products of Prebiotic Nucleotide Synthesis. J Am Chem Soc 2021; 143:3267-3279. [PMID: 33636080 DOI: 10.1021/jacs.0c12955] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in prebiotic chemistry are beginning to outline plausible pathways for the synthesis of the canonical ribonucleotides and their assembly into oligoribonucleotides. However, these reaction pathways suggest that many noncanonical nucleotides are likely to have been generated alongside the standard ribonucleotides. Thus, the oligomerization of prebiotically synthesized nucleotides is likely to have led to a highly heterogeneous collection of oligonucleotides comprised of a wide range of types of nucleotides connected by a variety of backbone linkages. How then did relatively homogeneous RNA emerge from this primordial heterogeneity? Here we focus on nonenzymatic template-directed primer extension as a process that would have strongly enriched for homogeneous RNA over the course of multiple cycles of replication. We review the effects on copying the kinetics of nucleotides with altered nucleobase and sugar moieties, when they are present as activated monomers and when they are incorporated into primer and template oligonucleotides. We also discuss three variations in backbone connectivity, all of which are nonheritable and regenerate native RNA upon being copied. The kinetic superiority of RNA synthesis suggests that nonenzymatic copying served as a chemical selection mechanism that allowed relatively homogeneous RNA to emerge from a complex mixture of prebiotically synthesized nucleotides and oligonucleotides.
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Affiliation(s)
- Seohyun Chris Kim
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Derek K O'Flaherty
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Constantin Giurgiu
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Lijun Zhou
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Jack W Szostak
- Howard Hughes Medical Institute, Department of Molecular Biology, and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.,Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, United States
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18
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Zhou ZX, Williams JS, Lujan SA, Kunkel TA. Ribonucleotide incorporation into DNA during DNA replication and its consequences. Crit Rev Biochem Mol Biol 2021; 56:109-124. [PMID: 33461360 DOI: 10.1080/10409238.2020.1869175] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ribonucleotides are the most abundant non-canonical nucleotides in the genome. Their vast presence and influence over genome biology is becoming increasingly appreciated. Here we review the recent progress made in understanding their genomic presence, incorporation characteristics and usefulness as biomarkers for polymerase enzymology. We also discuss ribonucleotide processing, the genetic consequences of unrepaired ribonucleotides in DNA and evidence supporting the significance of their transient presence in the nuclear genome.
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Affiliation(s)
- Zhi-Xiong Zhou
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Jessica S Williams
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Scott A Lujan
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
| | - Thomas A Kunkel
- Genome Integrity & Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, DHHS, Durham, NC, USA
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19
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Purhonen J, Banerjee R, McDonald AE, Fellman V, Kallijärvi J. A sensitive assay for dNTPs based on long synthetic oligonucleotides, EvaGreen dye and inhibitor-resistant high-fidelity DNA polymerase. Nucleic Acids Res 2020; 48:e87. [PMID: 32573728 PMCID: PMC7470940 DOI: 10.1093/nar/gkaa516] [Citation(s) in RCA: 295] [Impact Index Per Article: 73.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/15/2022] Open
Abstract
Deoxyribonucleoside triphosphates (dNTPs) are vital for the biosynthesis and repair of DNA. Their cellular concentration peaks during the S phase of the cell cycle. In non-proliferating cells, dNTP concentrations are low, making their reliable quantification from tissue samples of heterogeneous cellular composition challenging. Partly because of this, the current knowledge related to the regulation of and disturbances in cellular dNTP concentrations derive mostly from cell culture experiments with little corroboration at the tissue or organismal level. Here, we fill the methodological gap by presenting a simple non-radioactive microplate assay for the quantification of dNTPs with a minimum requirement of 4-12 mg of biopsy material. In contrast to published assays, this assay is based on long synthetic single-stranded DNA templates (50-200 nucleotides), an inhibitor-resistant high-fidelity DNA polymerase, and the double-stranded-DNA-binding EvaGreen dye. The assay quantified reliably less than 50 fmol of each of the four dNTPs and discriminated well against ribonucleotides. Additionally, thermostable RNAse HII-mediated nicking of the reaction products and a subsequent shift in their melting temperature allowed near-complete elimination of the interfering ribonucleotide signal, if present. Importantly, the assay allowed measurement of minute dNTP concentrations in mouse liver, heart and skeletal muscle.
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Affiliation(s)
- Janne Purhonen
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Rishi Banerjee
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | | | - Vineta Fellman
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland.,Department of Clinical Sciences, Lund, Pediatrics, Lund University, Sweden.,Children's Hospital, Helsinki University Hospital, Finland
| | - Jukka Kallijärvi
- Folkhälsan Research Center, Helsinki, Finland.,Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
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20
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Cerritelli SM, El Hage A. RNases H1 and H2: guardians of the stability of the nuclear genome when supply of dNTPs is limiting for DNA synthesis. Curr Genet 2020; 66:1073-1084. [PMID: 32886170 DOI: 10.1007/s00294-020-01086-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/30/2020] [Accepted: 06/01/2020] [Indexed: 11/29/2022]
Abstract
RNA/DNA hybrids are processed by RNases H1 and H2, while single ribonucleoside-monophosphates (rNMPs) embedded in genomic DNA are removed by the error-free, RNase H2-dependent ribonucleotide excision repair (RER) pathway. In the absence of RER, however, topoisomerase 1 (Top1) can cleave single genomic rNMPs in a mutagenic manner. In RNase H2-deficient mice, the accumulation of genomic rNMPs above a threshold of tolerance leads to catastrophic genomic instability that causes embryonic lethality. In humans, deficiencies in RNase H2 induce the autoimmune disorders Aicardi-Goutières syndrome and systemic lupus erythematosus, and cause skin and intestinal cancers. Recently, we reported that in Saccharomyces cerevisiae, the depletion of Rnr1, the major catalytic subunit of ribonucleotide reductase (RNR), which converts ribonucleotides to deoxyribonucleotides, leads to cell lethality in absence of RNases H1 and H2. We hypothesized that under replicative stress and compromised DNA repair that are elicited by an insufficient supply of deoxyribonucleoside-triphosphates (dNTPs), cells cannot survive the accumulation of persistent RNA/DNA hybrids. Remarkably, we found that cells lacking RNase H2 accumulate ~ 5-fold more genomic rNMPs in absence than in presence of Rnr1. When the load of genomic rNMPs is further increased in the presence of a replicative DNA polymerase variant that over-incorporates rNMPs in leading or lagging strand, cells missing both Rnr1 and RNase H2 suffer from severe growth defects. These are reversed in absence of Top1. Thus, in cells lacking RNase H2 and containing a limiting supply of dNTPs, there is a threshold of tolerance for the accumulation of genomic ribonucleotides that is tightly associated with Top1-mediated DNA damage. In this mini-review, we describe the implications of the loss of RNase H2, or RNases H1 and H2, on the integrity of the nuclear genome and viability of budding yeast cells that are challenged with a critically low supply of dNTPs. We further propose that our findings in budding yeast could pave the way for the study of the potential role of mammalian RNR in RNase H2-related diseases.
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Affiliation(s)
- Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Aziz El Hage
- The Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
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21
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22
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Zhao L, Sumberaz P. Mitochondrial DNA Damage: Prevalence, Biological Consequence, and Emerging Pathways. Chem Res Toxicol 2020; 33:2491-2502. [PMID: 32486637 DOI: 10.1021/acs.chemrestox.0c00083] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria have a plethora of functions within a eukaryotic cell, ranging from energy production, cell signaling, and protein cofactor synthesis to various aspects of metabolism. Mitochondrial dysfunction is known to cause over 200 named disorders and has been implicated in many human diseases and aging. Mitochondria have their own genetic material, mitochondrial DNA (mtDNA), which encodes 13 protein subunits in the oxidative phosphorylation system and a full set of transfer and rRNAs. Although more than 99% of the proteins in mitochondria are nuclear DNA (nDNA)-encoded, the integrity of mtDNA is critical for mitochondrial functions, as evidenced by mitochondrial diseases sourced from mtDNA mutations and depletions and the vital role of fragmented mtDNA molecules in cell signaling pathways. Previous research has shown that mtDNA is an important target of genotoxic assaults by a variety of chemical and physical factors. This Perspective discusses the prevalence of mtDNA damage by comparing the abundance of lesions in mDNA and nDNA and summarizes current knowledge on the biological pathways to cope with mtDNA damage, including mtDNA repair, mtDNA degradation, and mitochondrial fission and fusion. Also, emerging roles of mtDNA damage in mutagenesis and immune responses are reviewed.
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Affiliation(s)
- Linlin Zhao
- Department of Chemistry and Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521, United States
| | - Philip Sumberaz
- Department of Chemistry and Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521, United States
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23
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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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24
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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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25
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Role of Rad51 and DNA repair in cancer: A molecular perspective. Pharmacol Ther 2020; 208:107492. [PMID: 32001312 DOI: 10.1016/j.pharmthera.2020.107492] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/13/2020] [Accepted: 01/22/2020] [Indexed: 12/24/2022]
Abstract
The maintenance of genome integrity is essential for any organism survival and for the inheritance of traits to offspring. To the purpose, cells have developed a complex DNA repair system to defend the genetic information against both endogenous and exogenous sources of damage. Accordingly, multiple repair pathways can be aroused from the diverse forms of DNA lesions, which can be effective per se or via crosstalk with others to complete the whole DNA repair process. Deficiencies in DNA healing resulting in faulty repair and/or prolonged DNA damage can lead to genes mutations, chromosome rearrangements, genomic instability, and finally carcinogenesis and/or cancer progression. Although it might seem paradoxical, at the same time such defects in DNA repair pathways may have therapeutic implications for potential clinical practice. Here we provide an overview of the main DNA repair pathways, with special focus on the role played by homologous repair and the RAD51 recombinase protein in the cellular DNA damage response. We next discuss the recombinase structure and function per se and in combination with all its principal mediators and regulators. Finally, we conclude with an analysis of the manifold roles that RAD51 plays in carcinogenesis, cancer progression and anticancer drug resistance, and conclude this work with a survey of the most promising therapeutic strategies aimed at targeting RAD51 in experimental oncology.
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26
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Nishimura T, Baba M, Ogawa S, Kojima K, Takita T, Crouch RJ, Yasukawa K. Characterization of six recombinant human RNase H2 bearing Aicardi-Goutiéres syndrome causing mutations. J Biochem 2019; 166:537-545. [PMID: 31529068 DOI: 10.1093/jb/mvz073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/02/2019] [Indexed: 01/18/2023] Open
Abstract
Mammalian RNase H2 is a heterotrimeric enzyme consisting of one catalytic subunit (A) and two accessory subunits (B and C). RNase H2 is involved in the removal of a single ribonucleotide embedded in genomic DNA and removal of RNA of RNA/DNA hybrids. In humans, mutation of the RNase H2 gene causes a severe neuroinflammatory disorder Aicardi-Goutières syndrome (AGS). Here, we examined the activity and stability of six recombinant human RNase H2 variants bearing one AGS-causing mutation, A-G37S (Gly37 in the A subunit is replaced with Ser), A-N212I, A-R291H, B-A177T, B-V185G, or C-R69W. The activity of A-G37S was 0.3-1% of that of the wild-type RNase H2 (WT), while those of other five variants were 51-120%. In circular dichroism measurement, the melting temperatures of variants were 50-53°C, lower than that of WT (56°C). These results suggested that A-G37S had decreased activity and stability than WT, while other five variants had decreased stability but retained activity. In gel filtration chromatography of the purified enzyme preparation, WT migrated as a heterotrimer, while A-R291H eluted in two separate peaks containing either the heterotrimer or only the A subunit, suggesting that some AGS-causing mutations affect the heterotrimer-forming stability of RNase H2.
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Affiliation(s)
- Takuto Nishimura
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
| | - Misato Baba
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
| | - Saori Ogawa
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
| | - Kenji Kojima
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
| | - Teisuke Takita
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
| | - Robert J Crouch
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kiyoshi Yasukawa
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyoku, Kyoto 606-8502, Japan
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27
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Uehara R, Cerritelli SM, Hasin N, Sakhuja K, London M, Iranzo J, Chon H, Grinberg A, Crouch RJ. Two RNase H2 Mutants with Differential rNMP Processing Activity Reveal a Threshold of Ribonucleotide Tolerance for Embryonic Development. Cell Rep 2019; 25:1135-1145.e5. [PMID: 30380406 PMCID: PMC6309994 DOI: 10.1016/j.celrep.2018.10.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 09/18/2018] [Accepted: 10/03/2018] [Indexed: 11/30/2022] Open
Abstract
RNase H2 has two distinct functions: initiation of the ribonucleotide excision repair (RER) pathway by cleaving ribonucleotides (rNMPs) incorporated during DNA replication and processing the RNA portion of an R-loop formed during transcription. An RNase H2 mutant lacking RER activity but supporting R-loop removal revealed that rNMPs in DNA initiate p53-dependent DNA damage response and early embryonic arrest in mouse. However, an RNase H2 AGS-related mutant with residual RER activity develops to birth. Estimations of the number of rNMPs in DNA in these two mutants define a ribonucleotide threshold above which p53 induces apoptosis. Below the threshold, rNMPs in DNA trigger an innate immune response. Compound heterozygous cells, containing both defective enzymes, retain rNMPs above the threshold, indicative of competition for RER substrates between active and inactive enzymes, suggesting that patients with compound heterozygous mutations in RNASEH2 genes may not reflect the properties of recombinantly expressed proteins. Uehara et al. use RNase H2 mice with differing activity levels for removal of rNMPs embedded in DNA. Moderate levels of rNMPs lead to perinatal lethality activating the cGAS-Sting DNA sensing innate immune response. Exceeding a threshold, high abundance of rNMPs activates p53-dependent DNA damage, causing early embryonic lethality.
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Affiliation(s)
- Ryo Uehara
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Naushaba Hasin
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Kiran Sakhuja
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Mariya London
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Jaime Iranzo
- NCBI, National Library of Medicine, Bethesda, MD, USA
| | - Hyongi Chon
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Alexander Grinberg
- Mouse Core, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Robert J Crouch
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
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28
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Cerritelli SM, Crouch RJ. RNase H2-RED carpets the path to eukaryotic RNase H2 functions. DNA Repair (Amst) 2019; 84:102736. [PMID: 31761672 PMCID: PMC6936605 DOI: 10.1016/j.dnarep.2019.102736] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 10/15/2019] [Indexed: 11/24/2022]
Abstract
Eukaryotic RNases H2 have dual functions in initiating the removal of ribonucleoside monophosphates (rNMPs) incorporated by DNA polymerases during DNA synthesis and in cleaving the RNA moiety of RNA/DNA hybrids formed during transcription and retrotransposition. The other major cellular RNase H, RNase H1, shares the hybrid processing activity, but not all substrates. After RNase H2 incision at the rNMPs in DNA the Ribonucleotide Excision Repair (RER) pathway completes the removal, restoring dsDNA. The development of the RNase H2-RED (Ribonucleotide Excision Defective) mutant enzyme, which can process RNA/DNA hybrids but is unable to cleave rNMPs embedded in DNA has unlinked the two activities and illuminated the roles of RNase H2 in cellular metabolism. Studies mostly in Saccharomyces cerevisiae, have shown both activities of RNase H2 are necessary to maintain genome integrity and that RNase H1 and H2 have overlapping as well as distinct RNA/DNA hybrid substrates. In mouse RNase H2-RED confirmed that rNMPs in DNA during embryogenesis induce lethality in a p53-dependent DNA damage response. In mammalian cell cultures, RNase H2-RED helped identifying DNA lesions produced by Top1 cleavage at rNMPs and led to determine that RNase H2 participates in the retrotransposition of LINE-1 elements. In this review, we summarize the studies and conclusions reached by utilization of RNase H2-RED enzyme in different model systems.
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Affiliation(s)
- Susana M Cerritelli
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Crouch
- SFR, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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29
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Lietard J, Damha MJ, Somoza MM. Large-Scale Photolithographic Synthesis of Chimeric DNA/RNA Hairpin Microarrays To Explore Sequence Specificity Landscapes of RNase HII Cleavage. Biochemistry 2019; 58:4389-4397. [PMID: 31631649 PMCID: PMC6838787 DOI: 10.1021/acs.biochem.9b00806] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ribonuclease HII (RNase HII) is an essential endoribonuclease that binds to double-stranded DNA with RNA nucleotide incorporations and cleaves 5' of the ribonucleotide at RNA-DNA junctions. Thought to be present in all domains of life, RNase HII protects genomic integrity by initiating excision repair pathways that protect the encoded information from rapid degradation. There is sparse evidence that the enzyme cleaves some substrates better than others, but a large-scale study is missing. Such large-scale studies can be carried out on microarrays, and we employ chemical photolithography to synthesize very large combinatorial libraries of fluorescently labeled DNA/RNA chimeric sequences that self-anneal to form hairpin structures that are substrates for Escherichia coli RNase HII. The relative activity is determined by the loss of fluorescence upon cleavage. Each substrate includes a double-stranded 5 bp variable region with one to five consecutive ribonucleotide substitutions. We also examined the effect of all possible single and double mismatches, for a total of >9500 unique structures. Differences in cleavage efficiency indicate some level of substrate preference, and we identified the 5'-dC/rC-rA-dX-3' motif in well-cleaved substrates. The results significantly extend known patterns of RNase HII sequence specificity and serve as a template using large-scale photolithographic synthesis to comprehensively map landscapes of substrate specificity of nucleic acid-processing enzymes.
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Affiliation(s)
- Jory Lietard
- Institute of Inorganic Chemistry, Faculty of Chemistry , University of Vienna , Althanstraße 14 (UZA II) , 1090 Vienna , Austria
| | - Masad J Damha
- Department of Chemistry , McGill University , 801 Rue Sherbrooke Ouest , Montreal , QC H3A 0B8 , Canada
| | - Mark M Somoza
- Institute of Inorganic Chemistry, Faculty of Chemistry , University of Vienna , Althanstraße 14 (UZA II) , 1090 Vienna , Austria
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30
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Briggs E, Crouch K, Lemgruber L, Hamilton G, Lapsley C, McCulloch R. Trypanosoma brucei ribonuclease H2A is an essential R-loop processing enzyme whose loss causes DNA damage during transcription initiation and antigenic variation. Nucleic Acids Res 2019; 47:9180-9197. [PMID: 31350892 PMCID: PMC6753483 DOI: 10.1093/nar/gkz644] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/09/2019] [Accepted: 07/16/2019] [Indexed: 12/21/2022] Open
Abstract
Ribonucleotides represent a threat to DNA genome stability and transmission. Two types of Ribonuclease H (RNase H) excise ribonucleotides when they form part of the DNA strand, or hydrolyse RNA when it base-pairs with DNA in structures termed R-loops. Loss of either RNase H is lethal in mammals, whereas yeast survives the absence of both enzymes. RNase H1 loss is tolerated by the parasite Trypanosoma brucei but no work has examined the function of RNase H2. Here we show that loss of T. brucei RNase H2 (TbRH2A) leads to growth and cell cycle arrest that is concomitant with accumulation of nuclear damage at sites of RNA polymerase (Pol) II transcription initiation, revealing a novel and critical role for RNase H2. Differential gene expression analysis reveals limited overall changes in RNA levels for RNA Pol II genes after TbRH2A loss, but increased perturbation of nucleotide metabolic genes. Finally, we show that TbRH2A loss causes R-loop and DNA damage accumulation in telomeric RNA Pol I transcription sites, also leading to altered gene expression. Thus, we demonstrate separation of function between two nuclear T. brucei RNase H enzymes during RNA Pol II transcription, but overlap in function during RNA Pol I-mediated gene expression during host immune evasion.
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Affiliation(s)
- Emma Briggs
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Kathryn Crouch
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Leandro Lemgruber
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Graham Hamilton
- Glasgow Polyomics, University of Glasgow, Wolfson Wohl Cancer Research Centre, Garscube Estate, Switchback Rd, Bearsden G61 1QH, UK
| | - Craig Lapsley
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Richard McCulloch
- The Wellcome Centre for Integrative Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
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31
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Zou Z, Xu W, Mi C, Xu Y, Du K, Li B, Ye Y, Ling Y, Zhang H. Ribonucleoside triphosphates promote T7 DNA replication and the lysis of T7-Infected Escherichia coli. Biochimie 2019; 167:25-33. [PMID: 31493471 DOI: 10.1016/j.biochi.2019.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 09/01/2019] [Indexed: 11/19/2022]
Abstract
rNTPs are structurally similar to dNTPs, but their concentrations are much higher than those of dNTPs in cells. rNTPs in solutions or rNMP at the primer terminus or embedded in template always inhibit or block DNA replication, due to the reduced Mg2+ apparent concentration, competition of rNTPs with dNTPs, and the extra repulsive interaction of rNTP or rNMP with polymerase active site. In this work, unexpectedly, we found rNTPs can promote T7 DNA replication with the maximal promotion at rNTPs/dNTPs concentration ratio of 20. This promotion was not due to the optimized Mg2+ apparent concentration or the direct incorporation of extra rNMPs into DNA. This promotion was dependent on the concentrations and types of rNTPs. Kinetic analysis showed that this promotion was originated from the increased fraction of polymerase-DNA productive complex and the accelerated DNA polymerization. Further evidence showed that more polymerase-DNA complex was formed and their binding affinity was also enhanced in the presence of extra rNTPs. Moreover, this promotion in T7 DNA replication also accelerated the lysis of T7-infected host Escherichia coli. This work discovered that rNTPs could promote DNA replication, completely different from the traditional concept that rNTPs always inhibit DNA replication.
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Affiliation(s)
- 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
| | - Wendi Xu
- College of Biological Sciences and Engineering, North Minzu University, Yinchuan, Ningxia, 750021, China
| | - Chenyang Mi
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Ying Xu
- Key Laboratory of Environment and Female Reproductive Health, West China School of Public Health & West China Fourth Hospital, Sichuan University, Chengdu, 610041, China
| | - Ke Du
- 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
| | - Yang Ye
- Department of Obstetrics and Gynecology, Sun Yat-sen Memorial Hospital, Yanjiang West Road 107, Guangzhou, Guangdong, 510120, China
| | - Yihui Ling
- Institute for Chemical Carcinogenesis, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou, 510000, 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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32
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Malfatti MC, Henneke G, Balachander S, Koh KD, Newnam G, Uehara R, Crouch RJ, Storici F, Tell G. Unlike the Escherichia coli counterpart, archaeal RNase HII cannot process ribose monophosphate abasic sites and oxidized ribonucleotides embedded in DNA. J Biol Chem 2019; 294:13061-13072. [PMID: 31300556 DOI: 10.1074/jbc.ra119.009493] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/05/2019] [Indexed: 12/12/2022] Open
Abstract
The presence of ribonucleoside monophosphates (rNMPs) in nuclear DNA decreases genome stability. To ensure survival despite rNMP insertions, cells have evolved a complex network of DNA repair mechanisms, in which the ribonucleotide excision repair pathway, initiated by type 2 RNase H (RNase HII/2), plays a major role. We recently demonstrated that eukaryotic RNase H2 cannot repair damage, that is, ribose monophosphate abasic (both apurinic or apyrimidinic) site (rAP) or oxidized rNMP embedded in DNA. Currently, it remains unclear why RNase H2 is unable to repair these modified nucleic acids having either only a sugar moiety or an oxidized base. Here, we compared the endoribonuclease specificity of the RNase HII enzymes from the archaeon Pyrococcus abyssi and the bacterium Escherichia coli, examining their ability to process damaged rNMPs embedded in DNA in vitro We found that E. coli RNase HII cleaves both rAP and oxidized rNMP sites. In contrast, like the eukaryotic RNase H2, P. abyssi RNase HII did not display any rAP or oxidized rNMP incision activities, even though it recognized them. Notably, the archaeal enzyme was also inactive on a mismatched rNMP, whereas the E. coli enzyme displayed a strong preference for the mispaired rNMP over the paired rNMP in DNA. On the basis of our biochemical findings and also structural modeling analyses of RNase HII/2 proteins from organisms belonging to all three domains of life, we propose that RNases HII/2's dual roles in ribonucleotide excision repair and RNA/DNA hydrolysis result in limited acceptance of modified rNMPs embedded in DNA.
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Affiliation(s)
- Matilde Clarissa Malfatti
- Laboratory of Molecular Biology and DNA Repair, Department of Medicine, University of Udine, 33100 Udine, Italy
| | - Ghislaine Henneke
- Ifremer, Univ Brest, CNRS, Laboratoire de Microbiologie des Environnements Extrêmes, F-29280 Plouzané, France
| | - Sathya Balachander
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Kyung Duk Koh
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Gary Newnam
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Ryo Uehara
- Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Robert J Crouch
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
| | - Francesca Storici
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Gianluca Tell
- Laboratory of Molecular Biology and DNA Repair, Department of Medicine, University of Udine, 33100 Udine, Italy.
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33
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Wanrooij PH, Chabes A. Ribonucleotides in mitochondrial DNA. FEBS Lett 2019; 593:1554-1565. [PMID: 31093968 DOI: 10.1002/1873-3468.13440] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/09/2019] [Accepted: 05/09/2019] [Indexed: 01/05/2023]
Abstract
The incorporation of ribonucleotides (rNMPs) into DNA during genome replication has gained substantial attention in recent years and has been shown to be a significant source of genomic instability. Studies in yeast and mammals have shown that the two genomes, the nuclear DNA (nDNA) and the mitochondrial DNA (mtDNA), differ with regard to their rNMP content. This is largely due to differences in rNMP repair - whereas rNMPs are efficiently removed from the nuclear genome, mitochondria lack robust mechanisms for removal of single rNMPs incorporated during DNA replication. In this minireview, we describe the processes that determine the frequency of rNMPs in the mitochondrial genome and summarise recent findings regarding the effect of incorporated rNMPs on mtDNA stability and function.
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Affiliation(s)
- Paulina H Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Sweden
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34
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Tsukiashi M, Baba M, Kojima K, Himeda K, Takita T, Yasukawa K. Construction and characterization of ribonuclease H2 knockout NIH3T3 cells. J Biochem 2019; 165:249-256. [PMID: 30481312 DOI: 10.1093/jb/mvy101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 11/13/2018] [Indexed: 11/13/2022] Open
Abstract
Ribonuclease H (RNase H) specifically hydrolyzes the 5'-phosphodiester bonds of the RNA of RNA/DNA hybrid. Both types 1 and 2 RNases H act on the RNA strand of the hybrid, while only type 2 acts on the single ribonucleotide embedded in DNA duplex. In this study, to explore the role of mammalian type 2 RNase H (RNase H2) in cells, we constructed the RNase H2 knockout NIH3T3 cells (KO cells) by CRISPR/Cas9 system. KO cells hydrolyzed RNA strands in RNA/DNA hybrid, but not single ribonucleotides in DNA duplex, while wild-type NIH3T3 cells (WT cells) hydrolyzed both. Genomic DNA in the KO cells was more heavily hydrolyzed than in the WT cells by the alkaline or RNase H2 treatment, suggesting that the KO cells contained more ribonucleotides in genomic DNA than the WT cells. The growth rate of the KO cells was 60% of that of the WT cells. Expression of interferon-stimulated genes (ISGs) in the KO cells was not markedly elevated compared with the WT cells. These results suggest that in NIH3T3 cells, RNase H2 is crucial for suppressing the accumulation of ribonucleotides in genomic DNA but not for the expression of ISGs.
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Affiliation(s)
- Motoki Tsukiashi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Misato Baba
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kenji Kojima
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kohei Himeda
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Teisuke Takita
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kiyoshi Yasukawa
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan
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35
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Sassa A, Yasui M, Honma M. Current perspectives on mechanisms of ribonucleotide incorporation and processing in mammalian DNA. Genes Environ 2019; 41:3. [PMID: 30700998 PMCID: PMC6346524 DOI: 10.1186/s41021-019-0118-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/08/2019] [Indexed: 01/09/2023] Open
Abstract
Ribonucleotides, which are RNA precursors, are often incorporated into DNA during replication. Although embedded ribonucleotides in the genome are efficiently removed by canonical ribonucleotide excision repair (RER), inactivation of RER causes genomic ribonucleotide accumulation, leading to various abnormalities in cells. Mutation of genes encoding factors involved in RER is associated with the neuroinflammatory autoimmune disorder Aicardi–Goutières syndrome. Over the last decade, the biological impact of ribonucleotides in the genome has attracted much attention. In the present review, we particularly focus on recent studies that have elucidated possible mechanisms of ribonucleotide incorporation and repair and their significance in mammals.
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Affiliation(s)
- Akira Sassa
- 1Department of Biology, Graduate School of Science, Chiba University, Chiba, 263-8522 Japan
| | - Manabu Yasui
- 2Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501 Japan
| | - Masamitsu Honma
- 2Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki 210-9501 Japan
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36
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Mutations and Repair. Mol Biol 2019. [DOI: 10.1016/b978-0-12-813288-3.00026-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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37
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Briggs E, Hamilton G, Crouch K, Lapsley C, McCulloch R. Genome-wide mapping reveals conserved and diverged R-loop activities in the unusual genetic landscape of the African trypanosome genome. Nucleic Acids Res 2018; 46:11789-11805. [PMID: 30304482 PMCID: PMC6294496 DOI: 10.1093/nar/gky928] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 09/25/2018] [Accepted: 10/05/2018] [Indexed: 01/09/2023] Open
Abstract
R-loops are stable RNA-DNA hybrids that have been implicated in transcription initiation and termination, as well as in telomere maintenance, chromatin formation, and genome replication and instability. RNA Polymerase (Pol) II transcription in the protozoan parasite Trypanosoma brucei is highly unusual: virtually all genes are co-transcribed from multigene transcription units, with mRNAs generated by linked trans-splicing and polyadenylation, and transcription initiation sites display no conserved promoter motifs. Here, we describe the genome-wide distribution of R-loops in wild type mammal-infective T. brucei and in mutants lacking RNase H1, revealing both conserved and diverged functions. Conserved localization was found at centromeres, rRNA genes and retrotransposon-associated genes. RNA Pol II transcription initiation sites also displayed R-loops, suggesting a broadly conserved role despite the lack of promoter conservation or transcription initiation regulation. However, the most abundant sites of R-loop enrichment were within the regions between coding sequences of the multigene transcription units, where the hybrids coincide with sites of polyadenylation and nucleosome-depletion. Thus, instead of functioning in transcription termination the most widespread localization of R-loops in T. brucei suggests a novel correlation with pre-mRNA processing. Finally, we find little evidence for correlation between R-loop localization and mapped sites of DNA replication initiation.
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Affiliation(s)
- Emma Briggs
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Graham Hamilton
- Glasgow Polyomics, University of Glasgow, Wolfson Wohl Cancer Research Centre, Garscube Estate, Switchback Rd, Bearsden, G61 1QH, UK
| | - Kathryn Crouch
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Craig Lapsley
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
| | - Richard McCulloch
- The Wellcome Centre for Molecular Parasitology, University of Glasgow, College of Medical, Veterinary and Life Sciences, Institute of Infection, Immunity and Inflammation, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK
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38
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Zatopek KM, Gardner AF, Kelman Z. Archaeal DNA replication and repair: new genetic, biophysical and molecular tools for discovering and characterizing enzymes, pathways and mechanisms. FEMS Microbiol Rev 2018; 42:477-488. [PMID: 29912309 DOI: 10.1093/femsre/fuy017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 04/17/2018] [Indexed: 01/03/2023] Open
Abstract
DNA replication and repair are essential biological processes needed for the survival of all organisms. Although these processes are fundamentally conserved in the three domains, archaea, bacteria and eukarya, the proteins and complexes involved differ. The genetic and biophysical tools developed for archaea in the last several years have accelerated the study of DNA replication and repair in this domain. In this review, the current knowledge of DNA replication and repair processes in archaea will be summarized, with emphasis on the contribution of genetics and other recently developed biophysical and molecular tools, including capillary gel electrophoresis, next-generation sequencing and single-molecule approaches. How these new tools will continue to drive archaeal DNA replication and repair research will also be discussed.
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Affiliation(s)
| | | | - Zvi Kelman
- Biomolecular Labeling Laboratory, Institute for Bioscience and Biotechnology Research, National Institute of Standards and Technology and the University of Maryland, Rockville, MD 20850, USA
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39
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Hiller B, Hoppe A, Haase C, Hiller C, Schubert N, Müller W, Reijns MAM, Jackson AP, Kunkel TA, Wenzel J, Behrendt R, Roers A. Ribonucleotide Excision Repair Is Essential to Prevent Squamous Cell Carcinoma of the Skin. Cancer Res 2018; 78:5917-5926. [PMID: 30154151 DOI: 10.1158/0008-5472.can-18-1099] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 07/10/2018] [Accepted: 08/22/2018] [Indexed: 01/07/2023]
Abstract
Because of imperfect discrimination against ribonucleoside triphosphates by the replicative DNA polymerases, large numbers of ribonucleotides are incorporated into the eukaryotic nuclear genome during S-phase. Ribonucleotides, by far the most common DNA lesion in replicating cells, destabilize the DNA, and an evolutionarily conserved DNA repair machinery, ribonucleotide excision repair (RER), ensures ribonucleotide removal. Whereas complete lack of RER is embryonically lethal, partial loss-of-function mutations in the genes encoding subunits of RNase H2, the enzyme essential for initiation of RER, cause the SLE-related type I interferonopathy Aicardi-Goutières syndrome. Here, we demonstrate that selective inactivation of RER in mouse epidermis results in spontaneous DNA damage and epidermal hyperproliferation associated with loss of hair follicle stem cells and hair follicle function. The animals developed keratinocyte intraepithelial neoplasia and invasive squamous cell carcinoma with complete penetrance, despite potent type I interferon production and skin inflammation. These results suggest that compromises to RER-mediated genome maintenance might represent an important tumor-promoting principle in human cancer.Significance: Selective inactivation of ribonucleotide excision repair by loss of RNase H2 in the murine epidermis results in spontaneous DNA damage, type I interferon response, skin inflammation, and development of squamous cell carcinoma. Cancer Res; 78(20); 5917-26. ©2018 AACR.
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Affiliation(s)
- Björn Hiller
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany.,Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Anja Hoppe
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Christa Haase
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Christina Hiller
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Nadja Schubert
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Werner Müller
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Martin A M Reijns
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew P Jackson
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences (NIEHS), NIH, Research Triangle Park, North Carolina
| | - Jörg Wenzel
- Department of Dermatology and Allergy, University Hospital Bonn, Bonn, Germany
| | - Rayk Behrendt
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany.
| | - Axel Roers
- Institute for Immunology, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany.
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40
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Zou Z, Chen Z, Cai Y, Yang H, Du K, Li B, Jiang Y, Zhang H. Consecutive ribonucleoside monophosphates on template inhibit DNA replication by T7 DNA polymerase or by T7 polymerase and helicase complex. Biochimie 2018; 151:128-138. [DOI: 10.1016/j.biochi.2018.05.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 05/31/2018] [Indexed: 12/19/2022]
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41
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Kojima K, Baba M, Tsukiashi M, Nishimura T, Yasukawa K. RNA/DNA structures recognized by RNase H2. Brief Funct Genomics 2018; 18:169-173. [DOI: 10.1093/bfgp/ely024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Ribonuclease H (RNase H) [EC 3.1.26.4] is an enzyme that specifically degrades RNA from RNA/DNA hybrids. Since its discovery in 1969, the enzyme has been extensively studied for its catalytic mechanism and physiological role. RNase H has been classified into two major families, Type 1 and Type 2. Type 1 enzymes are designated RNase HI in prokaryotes and RNase H1 in eukaryotes, while Type 2 enzymes are designated RNase HII in prokaryotes and RNase H2 in eukaryotes. Type 2 enzymes are able to cleave the 5′-phosphodiester bond of one ribonucleotide embedded in a DNA double strand. Recent studies have shown that RNase H2 is involved in excision of a single ribonucleotide embedded in genomic DNA and removal of an R-loop formed in cells. It is also involved in double-strand break of DNA and its repair. In this review, we aim to outline the structures recognized by RNase H2.
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Affiliation(s)
- Kenji Kojima
- Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Misato Baba
- Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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42
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CRISPR screens identify genomic ribonucleotides as a source of PARP-trapping lesions. Nature 2018; 559:285-289. [PMID: 29973717 PMCID: PMC6071917 DOI: 10.1038/s41586-018-0291-z] [Citation(s) in RCA: 264] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 06/07/2018] [Indexed: 12/18/2022]
Abstract
The observation that BRCA1- and BRCA2-deficient cells are sensitive to poly(ADP-ribose) polymerase (PARP) inhibitors spurred their development into cancer therapies that target homologous recombination (HR) deficiency1. The cytotoxicity of PARP inhibitors depends on PARP trapping, the formation of non-covalent protein-DNA adducts composed of inhibited PARP1 bound to DNA lesions of unclear origins1–4. To address the nature of such lesions and the cellular consequences of PARP trapping, we undertook three CRISPR screens to identify genes and pathways that mediate cellular resistance to olaparib, a clinically approved PARP inhibitor1. Here were present a high-confidence set of 73 genes whose mutation causes increased PARP inhibitor sensitivity. In addition to an expected enrichment for HR-related genes, we discovered that mutation in all three genes encoding RNase H2 sensitized cells to PARP inhibition. We establish that the underlying cause of the PARP inhibitor hypersensitivity of RNase H2-deficient cells is impaired ribonucleotide excision repair (RER)5. Embedded ribonucleotides, abundant in the genome of RER-deficient cells, are substrates for topoisomerase 1 cleavage, resulting in PARP-trapping lesions that impede DNA replication and endanger genome integrity. We conclude that genomic ribonucleotides are a hitherto unappreciated source of PARP-trapping DNA lesions, and that the frequent deletion of RNASEH2B in metastatic prostate cancer and chronic lymphocytic leukemia could provide an opportunity to exploit these findings therapeutically.
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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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44
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General misincorporation frequency: Re-evaluation of the fidelity of DNA polymerases. Biochem Biophys Res Commun 2018; 496:1076-1081. [DOI: 10.1016/j.bbrc.2018.01.135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 01/21/2018] [Indexed: 01/07/2023]
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45
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Baba M, Kojima K, Nakase R, Imai S, Yamasaki T, Takita T, Crouch RJ, Yasukawa K. Effects of neutral salts and pH on the activity and stability of human RNase H2. J Biochem 2017; 162:211-219. [PMID: 28402412 DOI: 10.1093/jb/mvx021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 02/13/2017] [Indexed: 11/14/2022] Open
Abstract
Ribonuclease H (RNase H) specifically degrades the RNA of RNA/DNA hybrid. Recent study has shown that a single ribonucleotide is embedded in DNA double strand at every few thousand base pairs in human genome, and human RNase H2 is involved in its removal. Here, we examined the effects of neutral salts and pH on the activity and stability of human RNase H2. NaCl, KCl, RbCl and NaBr increased the activity to 170-390% at 10-60 mM, while LiCl, LiBr and CsCl inhibited it, suggesting that species of cation, but not anion, is responsible for the effect on activity. NaCl and KCl increased the stability by decreasing the first-order rate constant of the inactivation to 50-60% at 60-80 mM. The activity at 25-35 °C exhibited a narrow bell-shaped pH-dependence with the acidic and alkaline pKe (pKe1 and pKe2) values of 7.3 - 7.6 and 8.1 - 8.8, respectively. Enthalpy changes (ΔH°) of deprotonation were 5 ± 21 kJ mol-1 for pKe1 and 68 ± 25 kJ mol-1 for pKe2. These results suggest that the ionizable groups responsible for pKe1 may be two out of Asp34, Glu35 and Asp141 of DEDD motif, and that for pKe2 may be Lys69 of DSK motif.
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Affiliation(s)
- Misato Baba
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kenji Kojima
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Rihoko Nakase
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shota Imai
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Tomomi Yamasaki
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Teisuke Takita
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
| | - Robert J Crouch
- Section on Formation of RNA, Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kiyoshi Yasukawa
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Oiwakecho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
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Markkanen E. Not breathing is not an option: How to deal with oxidative DNA damage. DNA Repair (Amst) 2017; 59:82-105. [PMID: 28963982 DOI: 10.1016/j.dnarep.2017.09.007] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023]
Abstract
Oxidative DNA damage constitutes a major threat to genetic integrity, and has thus been implicated in the pathogenesis of a wide variety of diseases, including cancer and neurodegeneration. 7,8-dihydro-8oxo-deoxyGuanine (8-oxo-G) is one of the best characterised oxidative DNA lesions, and it can give rise to point mutations due to its miscoding potential that instructs most DNA polymerases (Pols) to preferentially insert Adenine (A) opposite 8-oxo-G instead of the correct Cytosine (C). If uncorrected, A:8-oxo-G mispairs can give rise to C:G→A:T transversion mutations. Cells have evolved a variety of pathways to mitigate the mutational potential of 8-oxo-G that include i) mechanisms to avoid incorporation of oxidized nucleotides into DNA through nucleotide pool sanitisation enzymes (by MTH1, MTH2, MTH3 and NUDT5), ii) base excision repair (BER) of 8-oxo-G in DNA (involving MUTYH, OGG1, Pol λ, and other components of the BER machinery), and iii) faithful bypass of 8-oxo-G lesions during replication (using a switch between replicative Pols and Pol λ). In the following, the fate of 8-oxo-G in mammalian cells is reviewed in detail. The differential origins of 8-oxo-G in DNA and its consequences for genetic stability will be covered. This will be followed by a thorough discussion of the different mechanisms in place to cope with 8-oxo-G with an emphasis on Pol λ-mediated correct bypass of 8-oxo-G during MUTYH-initiated BER as well as replication across 8-oxo-G. Furthermore, the multitude of mechanisms in place to regulate key proteins involved in 8-oxo-G repair will be reviewed. Novel functions of 8-oxo-G as an epigenetic-like regulator and insights into the repair of 8-oxo-G within the cellular context will be touched upon. Finally, a discussion will outline the relevance of 8-oxo-G and the proteins involved in dealing with 8-oxo-G to human diseases with a special emphasis on cancer.
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Affiliation(s)
- Enni Markkanen
- Institute of Veterinary Pharmacology and Toxicology, Vetsuisse Faculty, University of Zürich, Winterthurerstr. 260, 8057 Zürich, Switzerland.
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47
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Mentegari E, Crespan E, Bavagnoli L, Kissova M, Bertoletti F, Sabbioneda S, Imhof R, Sturla SJ, Nilforoushan A, Hübscher U, van Loon B, Maga G. Ribonucleotide incorporation by human DNA polymerase η impacts translesion synthesis and RNase H2 activity. Nucleic Acids Res 2017; 45:2600-2614. [PMID: 27994034 PMCID: PMC5389505 DOI: 10.1093/nar/gkw1275] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 12/07/2016] [Indexed: 12/25/2022] Open
Abstract
Ribonucleotides (rNs) incorporated in the genome by DNA polymerases (Pols) are removed by RNase H2. Cytidine and guanosine preferentially accumulate over the other rNs. Here we show that human Pol η can incorporate cytidine monophosphate (rCMP) opposite guanine, 8-oxo-7,8-dihydroguanine, 8-methyl-2΄-deoxyguanosine and a cisplatin intrastrand guanine crosslink (cis-PtGG), while it cannot bypass a 3-methylcytidine or an abasic site with rNs as substrates. Pol η is also capable of synthesizing polyribonucleotide chains, and its activity is enhanced by its auxiliary factor DNA Pol δ interacting protein 2 (PolDIP2). Human RNase H2 removes cytidine and guanosine less efficiently than the other rNs and incorporation of rCMP opposite DNA lesions further reduces the efficiency of RNase H2. Experiments with XP-V cell extracts indicate Pol η as the major basis of rCMP incorporation opposite cis-PtGG. These results suggest that translesion synthesis by Pol η can contribute to the accumulation of rCMP in the genome, particularly opposite modified guanines.
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Affiliation(s)
- Elisa Mentegari
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Emmanuele Crespan
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Laura Bavagnoli
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Miroslava Kissova
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Federica Bertoletti
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Simone Sabbioneda
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
| | - Ralph Imhof
- Department of Molecular Mechanisms of Disease, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Shana J Sturla
- Department of Health Sciences and Technology, ETH Zurich, Schmelzbergstrasse 9, CH-8092 Zürich, Switzerland
| | - Arman Nilforoushan
- Department of Health Sciences and Technology, ETH Zurich, Schmelzbergstrasse 9, CH-8092 Zürich, Switzerland
| | - Ulrich Hübscher
- Department of Molecular Mechanisms of Disease, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Barbara van Loon
- Department of Molecular Mechanisms of Disease, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Giovanni Maga
- DNA Enzymology & Molecular Virology and Cell Nucleus & DNA replication Units, Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy
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Abstract
Multiple DNA repair pathways maintain genome stability and ensure that DNA remains essentially unchanged over the life of a cell. Various human diseases occur if DNA repair is compromised, and most of these impact the nervous system, in some cases exclusively. However, it is often unclear what specific endogenous damage underpins disease pathology. Generally, the types of causative DNA damage are associated with replication, transcription, or oxidative metabolism; other direct sources of endogenous lesions may arise from aberrant topoisomerase activity or ribonucleotide incorporation into DNA. This review focuses on the etiology of DNA damage in the nervous system and the genome stability pathways that prevent human neurologic disease.
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Affiliation(s)
- Peter J McKinnon
- Department of Genetics, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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49
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Abstract
Genomic DNA is transiently contaminated with ribonucleotide residues during the process of DNA replication through misincorporation by the replicative DNA polymerases α, δ and ε, and by the normal replication process on the lagging strand, which uses RNA primers. These ribonucleotides are efficiently removed during replication by RNase H enzymes and the lagging strand synthesis machinery. However, when ribonucleotides remain in DNA they can distort the DNA helix, affect machineries for DNA replication, transcription and repair, and can stimulate genomic instabilities which are manifest as increased mutation, recombination and chromosome alterations. The genomic instabilities associated with embedded ribonucleotides are considered here, along with a discussion of the origin of the lesions that stimulate particular classes of instabilities.
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Affiliation(s)
- Hannah L Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA.
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50
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Heider MR, Burkhart BW, Santangelo TJ, Gardner AF. Defining the RNaseH2 enzyme-initiated ribonucleotide excision repair pathway in Archaea. J Biol Chem 2017; 292:8835-8845. [PMID: 28373277 PMCID: PMC5448109 DOI: 10.1074/jbc.m117.783472] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 03/31/2017] [Indexed: 11/06/2022] Open
Abstract
Incorporation of ribonucleotides during DNA replication has severe consequences for genome stability. Although eukaryotes possess a number of redundancies for initiating and completing repair of misincorporated ribonucleotides, archaea such as Thermococcus rely only upon RNaseH2 to initiate the pathway. Because Thermococcus DNA polymerases incorporate as many as 1,000 ribonucleotides per genome, RNaseH2 must be efficient at recognizing and nicking at embedded ribonucleotides to ensure genome integrity. Here, we show that ribonucleotides are incorporated by the hyperthermophilic archaeon Thermococcus kodakarensis both in vitro and in vivo and a robust ribonucleotide excision repair pathway is critical to keeping incorporation levels low in wild-type cells. Using pre-steady-state and steady-state kinetics experiments, we also show that archaeal RNaseH2 rapidly cleaves at embedded ribonucleotides (200-450 s-1), but exhibits an ∼1,000-fold slower turnover rate (0.06-0.17 s-1), suggesting a potential role for RNaseH2 in protecting or marking nicked sites for further processing. We found that following RNaseH2 cleavage, the combined activities of polymerase B (PolB), flap endonuclease (Fen1), and DNA ligase are required to complete ribonucleotide processing. PolB formed a ribonucleotide-containing flap by strand displacement synthesis that was cleaved by Fen1, and DNA ligase sealed the nick for complete repair. Our study reveals conservation of the overall mechanism of ribonucleotide excision repair across domains of life. The lack of redundancies in ribonucleotide repair in archaea perhaps suggests a more ancestral form of ribonucleotide excision repair compared with the eukaryotic pathway.
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Affiliation(s)
| | - Brett W Burkhart
- the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80521
| | - Thomas J Santangelo
- the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80521
| | - Andrew F Gardner
- From New England Biolabs, Inc., Ipswich, Massachusetts 01938 and
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