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Yáñez-Vilches A, Romero AM, Barrientos-Moreno M, Cruz E, González-Prieto R, Sharma S, Vertegaal ACO, Prado F. Physical interactions between specifically regulated subpopulations of the MCM and RNR complexes prevent genetic instability. PLoS Genet 2024; 20:e1011148. [PMID: 38776358 DOI: 10.1371/journal.pgen.1011148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 06/04/2024] [Accepted: 05/08/2024] [Indexed: 05/24/2024] Open
Abstract
The helicase MCM and the ribonucleotide reductase RNR are the complexes that provide the substrates (ssDNA templates and dNTPs, respectively) for DNA replication. Here, we demonstrate that MCM interacts physically with RNR and some of its regulators, including the kinase Dun1. These physical interactions encompass small subpopulations of MCM and RNR, are independent of the major subcellular locations of these two complexes, augment in response to DNA damage and, in the case of the Rnr2 and Rnr4 subunits of RNR, depend on Dun1. Partial disruption of the MCM/RNR interactions impairs the release of Rad52 -but not RPA-from the DNA repair centers despite the lesions are repaired, a phenotype that is associated with hypermutagenesis but not with alterations in the levels of dNTPs. These results suggest that a specifically regulated pool of MCM and RNR complexes plays non-canonical roles in genetic stability preventing persistent Rad52 centers and hypermutagenesis.
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Affiliation(s)
- Aurora Yáñez-Vilches
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
| | - Antonia M Romero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
| | - Marta Barrientos-Moreno
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
| | - Esther Cruz
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
| | - Román González-Prieto
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Alfred C O Vertegaal
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Félix Prado
- Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Consejo Superior de Investigaciones Científicas, Universidad de Sevilla, Universidad Pablo de Olavide, Seville, Spain
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2
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Yeast Ribonucleotide Reductase Is a Direct Target of the Proteasome and Provides Hyper Resistance to the Carcinogen 4-NQO. J Fungi (Basel) 2023; 9:jof9030351. [PMID: 36983519 PMCID: PMC10057556 DOI: 10.3390/jof9030351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 03/05/2023] [Accepted: 03/10/2023] [Indexed: 03/15/2023] Open
Abstract
Various external and internal factors damaging DNA constantly disrupt the stability of the genome. Cells use numerous dedicated DNA repair systems to detect damage and restore genomic integrity in a timely manner. Ribonucleotide reductase (RNR) is a key enzyme providing dNTPs for DNA repair. Molecular mechanisms of indirect regulation of yeast RNR activity are well understood, whereas little is known about its direct regulation. The study was aimed at elucidation of the proteasome-dependent mechanism of direct regulation of RNR subunits in Saccharomyces cerevisiae. Proteome analysis followed by Western blot, RT-PCR, and yeast plating analysis showed that upregulation of RNR by proteasome deregulation is associated with yeast hyper resistance to 4-nitroquinoline-1-oxide (4-NQO), a UV-mimetic DNA-damaging drug used in animal models to study oncogenesis. Inhibition of RNR or deletion of RNR regulatory proteins reverses the phenotype of yeast hyper resistance to 4-NQO. We have shown for the first time that the yeast Rnr1 subunit is a substrate of the proteasome, which suggests a common mechanism of RNR regulation in yeast and mammals.
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3
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Reusswig KU, Bittmann J, Peritore M, Courtes M, Pardo B, Wierer M, Mann M, Pfander B. Unscheduled DNA replication in G1 causes genome instability and damage signatures indicative of replication collisions. Nat Commun 2022; 13:7014. [PMID: 36400763 PMCID: PMC9674678 DOI: 10.1038/s41467-022-34379-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/24/2022] [Indexed: 11/19/2022] Open
Abstract
DNA replicates once per cell cycle. Interfering with the regulation of DNA replication initiation generates genome instability through over-replication and has been linked to early stages of cancer development. Here, we engineer genetic systems in budding yeast to induce unscheduled replication in a G1-like cell cycle state. Unscheduled G1 replication initiates at canonical S-phase origins. We quantifiy the composition of replisomes in G1- and S-phase and identified firing factors, polymerase α, and histone supply as factors that limit replication outside S-phase. G1 replication per se does not trigger cellular checkpoints. Subsequent replication during S-phase, however, results in over-replication and leads to chromosome breaks and chromosome-wide, strand-biased occurrence of RPA-bound single-stranded DNA, indicating head-to-tail replication collisions as a key mechanism generating genome instability upon G1 replication. Low-level, sporadic induction of G1 replication induces an identical response, indicating findings from synthetic systems are applicable to naturally occurring scenarios of unscheduled replication initiation.
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Affiliation(s)
- Karl-Uwe Reusswig
- grid.418615.f0000 0004 0491 845XDNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ,grid.38142.3c000000041936754XPresent Address: Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115 USA ,grid.65499.370000 0001 2106 9910Present Address: Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215 USA
| | - Julia Bittmann
- grid.418615.f0000 0004 0491 845XDNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Martina Peritore
- grid.418615.f0000 0004 0491 845XDNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ,grid.7551.60000 0000 8983 7915Present Address: Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany
| | - Mathilde Courtes
- grid.433120.7Institut de Génétique Humaine (IGH), Université de Montpellier – Centre National de la Recherche Scientifique, 34396 Montpellier, France
| | - Benjamin Pardo
- grid.433120.7Institut de Génétique Humaine (IGH), Université de Montpellier – Centre National de la Recherche Scientifique, 34396 Montpellier, France
| | - Michael Wierer
- grid.418615.f0000 0004 0491 845XProteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ,grid.5254.60000 0001 0674 042XPresent Address: Proteomics Research Infrastructure, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Matthias Mann
- grid.418615.f0000 0004 0491 845XProteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Boris Pfander
- grid.418615.f0000 0004 0491 845XDNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany ,grid.7551.60000 0000 8983 7915Present Address: Genome Maintenance Mechanisms in Health and Disease, Institute of Aerospace Medicine, German Aerospace Center (DLR), 51147 Cologne, Germany ,grid.6190.e0000 0000 8580 3777Present Address: Genome Maintenance Mechanisms in Health and Disease, Institute of Genome Stability in Ageing and Disease, CECAD Research Center, University of Cologne, 50931 Cologne, Germany
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4
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Ventroux M, Noirot-Gros MF. Prophage-encoded small protein YqaH counteracts the activities of the replication initiator DnaA in Bacillus subtilis. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 36748575 DOI: 10.1099/mic.0.001268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Bacterial genomes harbour cryptic prophages that are mostly transcriptionally silent with many unannotated genes. Still, cryptic prophages may contribute to their host fitness and phenotypes. In Bacillus subtilis, the yqaF-yqaN operon belongs to the prophage element skin, and is tightly repressed by the Xre-like repressor SknR. This operon contains several small ORFs (smORFs) potentially encoding small-sized proteins. The smORF-encoded peptide YqaH was previously reported to bind to the replication initiator DnaA. Here, using a yeast two-hybrid assay, we found that YqaH binds to the DNA binding domain IV of DnaA and interacts with Spo0A, a master regulator of sporulation. We isolated single amino acid substitutions in YqaH that abolished the interaction with DnaA but not with Spo0A. Then, using a plasmid-based inducible system to overexpress yqaH WT and mutant derivatives, we studied in B. subtilis the phenotypes associated with the specific loss-of-interaction with DnaA (DnaA_LOI). We found that expression of yqaH carrying DnaA_LOI mutations abolished the deleterious effects of yqaH WT expression on chromosome segregation, replication initiation and DnaA-regulated transcription. When YqaH was induced after vegetative growth, DnaA_LOI mutations abolished the drastic effects of YqaH WT on sporulation and biofilm formation. Thus, YqaH inhibits replication, sporulation and biofilm formation mainly by antagonizing DnaA in a manner that is independent of the cell cycle checkpoint Sda.
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Affiliation(s)
- Magali Ventroux
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
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5
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A DNA Replication Fork-centric View of the Budding Yeast DNA Damage Response. DNA Repair (Amst) 2022; 119:103393. [DOI: 10.1016/j.dnarep.2022.103393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 11/23/2022]
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6
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Long MJC, Ly P, Aye Y. Still no Rest for the Reductases: Ribonucleotide Reductase (RNR) Structure and Function: An Update. Subcell Biochem 2022; 99:155-197. [PMID: 36151376 DOI: 10.1007/978-3-031-00793-4_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Herein we present a multidisciplinary discussion of ribonucleotide reductase (RNR), the essential enzyme uniquely responsible for conversion of ribonucleotides to deoxyribonucleotides. This chapter primarily presents an overview of this multifaceted and complex enzyme, covering RNR's role in enzymology, biochemistry, medicinal chemistry, and cell biology. It further focuses on RNR from mammals, whose interesting and often conflicting roles in health and disease are coming more into focus. We present pitfalls that we think have not always been dealt with by researchers in each area and further seek to unite some of the field-specific observations surrounding this enzyme. Our work is thus not intended to cover any one topic in extreme detail, but rather give what we consider to be the necessary broad grounding to understand this critical enzyme holistically. Although this is an approach we have advocated in many different areas of scientific research, there is arguably no other single enzyme that embodies the need for such broad study than RNR. Thus, we submit that RNR itself is a paradigm of interdisciplinary research that is of interest from the perspective of the generalist and the specialist alike. We hope that the discussions herein will thus be helpful to not only those wanting to tackle RNR-specific problems, but also those working on similar interdisciplinary projects centering around other enzymes.
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Affiliation(s)
- Marcus J C Long
- University of Lausanne (UNIL), Lausanne, Switzerland
- Department of Biochemistry, UNIL, Epalinges, Switzerland
| | - Phillippe Ly
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- EPFL SB ISIC LEAGO, Lausanne, Switzerland
| | - Yimon Aye
- Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- EPFL SB ISIC LEAGO, Lausanne, Switzerland.
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7
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Sun H, Lu Z, Singh A, Zhou Y, Zheng E, Zhou M, Wang J, Wu X, Hu Z, Gu Z, Campbell JL, Zheng L, Shen B. Error-prone, stress-induced 3' flap-based Okazaki fragment maturation supports cell survival. Science 2021; 374:1252-1258. [PMID: 34855483 DOI: 10.1126/science.abj1013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Haitao Sun
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Zhaoning Lu
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Amanpreet Singh
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Yajing Zhou
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Eric Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.,Department of Molecular, Cellular, and Developmental Biology, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Mian Zhou
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Jinhui Wang
- Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Xiwei Wu
- Department of Molecular and Cellular Biology, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Zunsong Hu
- Department of Computational and Quantitative Medicine, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Zhaohui Gu
- Department of Computational and Quantitative Medicine, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Judith L Campbell
- Braun Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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8
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Ozturk M, Metin M, Altay V, De Filippis L, Ünal BT, Khursheed A, Gul A, Hasanuzzaman M, Nahar K, Kawano T, Caparrós PG. Molecular Biology of Cadmium Toxicity in Saccharomyces cerevisiae. Biol Trace Elem Res 2021; 199:4832-4846. [PMID: 33462792 DOI: 10.1007/s12011-021-02584-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/08/2021] [Indexed: 02/08/2023]
Abstract
Cadmium (Cd) is a toxic heavy metal mainly originating from industrial activities and causes environmental pollution. To better understand its toxicity and pollution remediation, we must understand the effects of Cd on living beings. Saccharomyces cerevisiae (budding yeast) is an eukaryotic unicellular model organism. It has provided much scientific knowledge about cellular and molecular biology in addition to its economic benefits. Effects associated with copper and zinc, sulfur and selenium metabolism, calcium (Ca2+) balance/signaling, and structure of phospholipids as a result of exposure to cadmium have been evaluated. In yeast as a result of cadmium stress, "mitogen-activated protein kinase," "high osmolarity glycerol," and "cell wall integrity" pathways have been reported to activate different signaling pathways. In addition, abnormalities and changes in protein structure, ribosomes, cell cycle disruption, and reactive oxygen species (ROS) following cadmium cytotoxicity have also been detailed. Moreover, the key OLE1 gene that encodes for delta-9 FA desaturase in relation to cadmium toxicity has been discussed in more detail. Keeping all these studies in mind, an attempt has been made to evaluate published cellular and molecular toxicity data related to Cd stress, and specifically published on S. cerevisiae.
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Affiliation(s)
- Munir Ozturk
- Department of Botany and Centre for Environmental Studies, Ege University, Izmir, Turkey.
| | - Mert Metin
- Graduate School of Environmental Engineering, The University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka, 808-0135, Japan
| | - Volkan Altay
- Department of Biology, Faculty of Science and Arts, Hatay Mustafa Kemal University, Antakya, Hatay, Turkey
| | - Luigi De Filippis
- School of Life Sciences, University of Technology Sydney, Sydney, 123, Australia
| | - Bengu Turkyilmaz Ünal
- Faculty of Science and Arts, Department of Biotechnology, Nigde Omer Halisdemir University, Nigde, Turkey
| | - Anum Khursheed
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-I-Azam University, Islamabad, Pakistan
| | - Alvina Gul
- Atta-ur-Rahman School of Applied Biosciences, National University of Sciences & Technology, Islamabad, Pakistan
| | - Mirza Hasanuzzaman
- Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Kamuran Nahar
- Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Tomonori Kawano
- Graduate School of Environmental Engineering, The University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka, 808-0135, Japan
| | - Pedro García Caparrós
- Agronomy Department of Superior School Engineering, University of Almería, Ctra. Sacramento s/n, La Cañadade San Urbano, 04120, Almería, Spain
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9
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Saccharomyces cerevisiae as a Tool for Studying Mutations in Nuclear Genes Involved in Diseases Caused by Mitochondrial DNA Instability. Genes (Basel) 2021; 12:genes12121866. [PMID: 34946817 PMCID: PMC8701800 DOI: 10.3390/genes12121866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/20/2021] [Accepted: 11/23/2021] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial DNA (mtDNA) maintenance is critical for oxidative phosphorylation (OXPHOS) since some subunits of the respiratory chain complexes are mitochondrially encoded. Pathological mutations in nuclear genes involved in the mtDNA metabolism may result in a quantitative decrease in mtDNA levels, referred to as mtDNA depletion, or in qualitative defects in mtDNA, especially in multiple deletions. Since, in the last decade, most of the novel mutations have been identified through whole-exome sequencing, it is crucial to confirm the pathogenicity by functional analysis in the appropriate model systems. Among these, the yeast Saccharomyces cerevisiae has proved to be a good model for studying mutations associated with mtDNA instability. This review focuses on the use of yeast for evaluating the pathogenicity of mutations in six genes, MPV17/SYM1, MRM2/MRM2, OPA1/MGM1, POLG/MIP1, RRM2B/RNR2, and SLC25A4/AAC2, all associated with mtDNA depletion or multiple deletions. We highlight the techniques used to construct a specific model and to measure the mtDNA instability as well as the main results obtained. We then report the contribution that yeast has given in understanding the pathogenic mechanisms of the mutant variants, in finding the genetic suppressors of the mitochondrial defects and in the discovery of molecules able to improve the mtDNA stability.
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10
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Tannous EA, Burgers PM. Novel insights into the mechanism of cell cycle kinases Mec1(ATR) and Tel1(ATM). Crit Rev Biochem Mol Biol 2021; 56:441-454. [PMID: 34151669 DOI: 10.1080/10409238.2021.1925218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA replication is a highly precise process which usually functions in a perfect rhythm with cell cycle progression. However, cells are constantly faced with various kinds of obstacles such as blocks in DNA replication, lack of availability of precursors and improper chromosome alignment. When these problems are not addressed, they may lead to chromosome instability and the accumulation of mutations, and even cell death. Therefore, the cell has developed response mechanisms to keep most of these situations under control. Of the many factors that participate in this DNA damage response, members of the family of phosphatidylinositol 3-kinase-related protein kinases (PIKKs) orchestrate the response landscape. Our understanding of two members of the PIKK family, human ATR (yeast Mec1) and ATM (yeast Tel1), and their associated partner proteins, has shown substantial progress through recent biochemical and structural studies. Emerging structural information of these unique kinases show common features that reveal the mechanism of kinase activity.
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Affiliation(s)
- Elias A Tannous
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
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11
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Tannous EA, Yates LA, Zhang X, Burgers PM. Mechanism of auto-inhibition and activation of Mec1 ATR checkpoint kinase. Nat Struct Mol Biol 2020; 28:50-61. [PMID: 33169019 PMCID: PMC7855233 DOI: 10.1038/s41594-020-00522-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023]
Abstract
In response to DNA damage or replication fork stalling, the basal activity of Mec1ATR is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1ATR dysfunction leads to cell death in yeast and causes chromosome instability and embryonic lethality in mammals. Thus, ATR is a major target for cancer therapies in homologous recombination-deficient cancers. Here we identify a single mutation in Mec1, conserved in ATR, that results in constitutive activity. Using cryo-electron microscopy, we determine the structures of this constitutively active form (Mec1(F2244L)-Ddc2) at 2.8 Å and the wild type at 3.8 Å, both in complex with Mg2+-AMP-PNP. These structures yield a near-complete atomic model for Mec1-Ddc2 and uncover the molecular basis for low basal activity and the conformational changes required for activation. Combined with biochemical and genetic data, we discover key regulatory regions and propose a Mec1 activation mechanism.
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Affiliation(s)
- Elias A Tannous
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK.
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA.
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12
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Woo TT, Chuang CN, Higashide M, Shinohara A, Wang TF. Dual roles of yeast Rad51 N-terminal domain in repairing DNA double-strand breaks. Nucleic Acids Res 2020; 48:8474-8489. [PMID: 32652040 PMCID: PMC7470947 DOI: 10.1093/nar/gkaa587] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 06/24/2020] [Accepted: 07/03/2020] [Indexed: 01/17/2023] Open
Abstract
Highly toxic DNA double-strand breaks (DSBs) readily trigger the DNA damage response (DDR) in cells, which delays cell cycle progression to ensure proper DSB repair. In Saccharomyces cerevisiae, mitotic S phase (20–30 min) is lengthened upon DNA damage. During meiosis, Spo11-induced DSB onset and repair lasts up to 5 h. We report that the NH2-terminal domain (NTD; residues 1–66) of Rad51 has dual functions for repairing DSBs during vegetative growth and meiosis. Firstly, Rad51-NTD exhibits autonomous expression-enhancing activity for high-level production of native Rad51 and when fused to exogenous β-galactosidase in vivo. Secondly, Rad51-NTD is an S/T-Q cluster domain (SCD) harboring three putative Mec1/Tel1 target sites. Mec1/Tel1-dependent phosphorylation antagonizes the proteasomal degradation pathway, increasing the half-life of Rad51 from ∼30 min to ≥180 min. Our results evidence a direct link between homologous recombination and DDR modulated by Rad51 homeostasis.
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Affiliation(s)
- Tai-Ting Woo
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chi-Ning Chuang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Mika Higashide
- Laboratory of Genome-Chromosome Functions, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Japan
| | - Akira Shinohara
- Laboratory of Genome-Chromosome Functions, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Japan
| | - Ting-Fang Wang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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13
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Cell-cycle-dependent phosphorylation of RRM1 ensures efficient DNA replication and regulates cancer vulnerability to ATR inhibition. Oncogene 2020; 39:5721-5733. [PMID: 32712628 DOI: 10.1038/s41388-020-01403-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 07/14/2020] [Accepted: 07/20/2020] [Indexed: 11/08/2022]
Abstract
Ribonucleotide reductase (RNR) catalyzes the rate-limiting step of de novo synthesis of deoxyribonucleotide triphosphates (dNTPs) building blocks for DNA synthesis, and is a well-recognized target for cancer therapy. RNR is a heterotetramer consisting of two large RRM1 subunits and two small RRM2 subunits. RNR activity is greatly stimulated by transcriptional activation of RRM2 during S/G2 phase to ensure adequate dNTP supply for DNA replication. However, little is known about the cell-cycle-dependent regulation of RNR activity through RRM1. Here, we report that RRM1 is phosphorylated at Ser 559 by CDK2/cyclin A during S/G2 phase. And this S559 phosphorylation of RRM1enhances RNR enzymatic activity and is required for maintaining sufficient dNTPs during normal DNA replication. Defective RRM1 S559 phosphorylation causes DNA replication stress, double-strand break, and genomic instability. Moreover, combined targeting of RRM1 S559 phosphorylation and ATR triggers lethal replication stress and profound antitumor effects. Thus, this posttranslational phosphorylation of RRM1 provides an alternative mechanism to finely regulating RNR and therapeutic opportunities for cancer treatment.
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14
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The yeast Aft1 transcription factor activates ribonucleotide reductase catalytic subunit RNR1 in response to iron deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194522. [PMID: 32147528 DOI: 10.1016/j.bbagrm.2020.194522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/25/2020] [Accepted: 03/01/2020] [Indexed: 12/18/2022]
Abstract
Eukaryotic ribonucleotide reductases are iron-dependent enzymes that catalyze the rate-limiting step in the de novo synthesis of deoxyribonucleotides. Multiple mechanisms regulate the activity of ribonucleotide reductases in response to genotoxic stresses and iron deficiency. Upon iron starvation, the Saccharomyces cerevisiae Aft1 transcription factor specifically binds to iron-responsive cis elements within the promoter of a group of genes, known as the iron regulon, activating their transcription. Members of the iron regulon participate in iron acquisition, mobilization and recycling, and trigger a genome-wide metabolic remodeling of iron-dependent pathways. Here, we describe a mechanism that optimizes the activity of yeast ribonucleotide reductase when iron is scarce. We demonstrate that Aft1 and the DNA-binding protein Ixr1 enhance the expression of the gene encoding for its catalytic subunit, RNR1, in response to iron limitation, leading to an increase in both mRNA and protein levels. By mutagenesis of the Aft1-binding sites within RNR1 promoter, we conclude that RNR1 activation by iron depletion is important for Rnr1 protein and deoxyribonucleotide synthesis. Remarkably, Aft1 also activates the expression of IXR1 upon iron scarcity through an iron-responsive element located within its promoter. These results provide a novel mechanism for the direct activation of ribonucleotide reductase function by the iron-regulated Aft1 transcription factor.
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15
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Affiliation(s)
- Nerea Sanvisens Delgado
- UCSF Helen Diller Comprehensive Cancer Center, Univerisity of Califorinia, San Francisco, California, United States of America
| | - David P. Toczyski
- UCSF Helen Diller Comprehensive Cancer Center, Univerisity of Califorinia, San Francisco, California, United States of America
- * E-mail:
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Li X, Jin X, Sharma S, Liu X, Zhang J, Niu Y, Li J, Li Z, Zhang J, Cao Q, Hou W, Du LL, Liu B, Lou H. Mck1 defines a key S-phase checkpoint effector in response to various degrees of replication threats. PLoS Genet 2019; 15:e1008136. [PMID: 31381575 PMCID: PMC6695201 DOI: 10.1371/journal.pgen.1008136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 08/15/2019] [Accepted: 07/19/2019] [Indexed: 01/23/2023] Open
Abstract
The S-phase checkpoint plays an essential role in regulation of the ribonucleotide reductase (RNR) activity to maintain the dNTP pools. How eukaryotic cells respond appropriately to different levels of replication threats remains elusive. Here, we have identified that a conserved GSK-3 kinase Mck1 cooperates with Dun1 in regulating this process. Deleting MCK1 sensitizes dun1Δ to hydroxyurea (HU) reminiscent of mec1Δ or rad53Δ. While Mck1 is downstream of Rad53, it does not participate in the post-translational regulation of RNR as Dun1 does. Mck1 phosphorylates and releases the Crt1 repressor from the promoters of DNA damage-inducible genes as RNR2-4 and HUG1. Hug1, an Rnr2 inhibitor normally silenced, is induced as a counterweight to excessive RNR. When cells suffer a more severe threat, Mck1 inhibits HUG1 transcription. Consistently, only a combined deletion of HUG1 and CRT1, confers a dramatic boost of dNTP levels and the survival of mck1Δdun1Δ or mec1Δ cells assaulted by a lethal dose of HU. These findings reveal the division-of-labor between Mck1 and Dun1 at the S-phase checkpoint pathway to fine-tune dNTP homeostasis.
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Affiliation(s)
- Xiaoli Li
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Xuejiao Jin
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Hangzhou, China
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan, Gothenburg, Sweden
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Xiaojing Liu
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Jiaxin Zhang
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Yanling Niu
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Jiani Li
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Zhen Li
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Jingjing Zhang
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Qinhong Cao
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Wenya Hou
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
| | - Li-Lin Du
- National Institute of Biological Sciences, Beijing, China
| | - Beidong Liu
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin’an, Hangzhou, China
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan, Gothenburg, Sweden
- * E-mail: (BL); (HL)
| | - Huiqiang Lou
- State Key Laboratory of Agro-Biotechnology and Beijing Advanced Innovation Center for Food Nutrition and Human Health, MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, P.R. China
- * E-mail: (BL); (HL)
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Saatchi F, Kirchmaier AL. Tolerance of DNA Replication Stress Is Promoted by Fumarate Through Modulation of Histone Demethylation and Enhancement of Replicative Intermediate Processing in Saccharomyces cerevisiae. Genetics 2019; 212:631-654. [PMID: 31123043 PMCID: PMC6614904 DOI: 10.1534/genetics.119.302238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 05/07/2019] [Indexed: 12/28/2022] Open
Abstract
Fumarase is a well-characterized TCA cycle enzyme that catalyzes the reversible conversion of fumarate to malate. In mammals, fumarase acts as a tumor suppressor, and loss-of-function mutations in the FH gene in hereditary leiomyomatosis and renal cell cancer result in the accumulation of intracellular fumarate-an inhibitor of α-ketoglutarate-dependent dioxygenases. Fumarase promotes DNA repair by nonhomologous end joining in mammalian cells through interaction with the histone variant H2A.Z, and inhibition of KDM2B, a H3 K36-specific histone demethylase. Here, we report that Saccharomyces cerevisiae fumarase, Fum1p, acts as a response factor during DNA replication stress, and fumarate enhances survival of yeast lacking Htz1p (H2A.Z in mammals). We observed that exposure to DNA replication stress led to upregulation as well as nuclear enrichment of Fum1p, and raising levels of fumarate in cells via deletion of FUM1 or addition of exogenous fumarate suppressed the sensitivity to DNA replication stress of htz1Δ mutants. This suppression was independent of modulating nucleotide pool levels. Rather, our results are consistent with fumarate conferring resistance to DNA replication stress in htz1Δ mutants by inhibiting the H3 K4-specific histone demethylase Jhd2p, and increasing H3 K4 methylation. Although the timing of checkpoint activation and deactivation remained largely unaffected by fumarate, sensors and mediators of the DNA replication checkpoint were required for fumarate-dependent resistance to replication stress in the htz1Δ mutants. Together, our findings imply metabolic enzymes and metabolites aid in processing replicative intermediates by affecting chromatin modification states, thereby promoting genome integrity.
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Affiliation(s)
- Faeze Saatchi
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
| | - Ann L Kirchmaier
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907
- Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
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Versatility of the Mec1 ATM/ATR signaling network in mediating resistance to replication, genotoxic, and proteotoxic stresses. Curr Genet 2019; 65:657-661. [PMID: 30610294 PMCID: PMC6510830 DOI: 10.1007/s00294-018-0920-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 01/11/2023]
Abstract
The ataxia-telangiectasia mutated/ATM and Rad3-related (ATM/ATR) family proteins are evolutionarily conserved serine/threonine kinases best known for their roles in mediating the DNA damage response. Upon activation, ATM/ATR phosphorylate numerous targets to stabilize stalled replication forks, repair damaged DNA, and inhibit cell cycle progression to ensure survival of the cell and safeguard integrity of the genome. Intriguingly, separation of function alleles of the human ATM and MEC1, the budding yeast ATM/ATR, were shown to confer widespread protein aggregation and acute sensitivity to different types of proteotoxic agents including heavy metal, amino acid analogue, and an aggregation-prone peptide derived from the Huntington’s disease protein. Further analyses unveiled that ATM and Mec1 promote resistance to perturbation in protein homeostasis via a mechanism distinct from the DNA damage response. In this minireview, we summarize the key findings and discuss ATM/ATR as a multifaceted signalling protein capable of mediating cellular response to both DNA and protein damage.
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Corcoles-Saez I, Dong K, Johnson AL, Waskiewicz E, Costanzo M, Boone C, Cha RS. Essential Function of Mec1, the Budding Yeast ATM/ATR Checkpoint-Response Kinase, in Protein Homeostasis. Dev Cell 2018; 46:495-503.e2. [DOI: 10.1016/j.devcel.2018.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/22/2018] [Accepted: 07/13/2018] [Indexed: 12/29/2022]
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20
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Upregulation of dNTP Levels After Telomerase Inactivation Influences Telomerase-Independent Telomere Maintenance Pathway Choice in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2018; 8:2551-2558. [PMID: 29848621 PMCID: PMC6071591 DOI: 10.1534/g3.118.200280] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In 10–15% of cancers, telomere length is maintained by a telomerase-independent, recombination-mediated pathway called alternative lengthening of telomeres (ALT). ALT mechanisms were first seen, and have been best studied, in telomerase-null Saccharomyces cerevisiae cells called “survivors”. There are two main types of survivors. Type I survivors amplify Y′ subtelomeric elements while type II survivors, similar to the majority of human ALT cells, amplify the terminal telomeric repeats. Both types of survivors require Rad52, a key homologous recombination protein, and Pol32, a non-essential subunit of DNA polymerase δ. A number of additional proteins have been reported to be important for either type I or type II survivor formation, but it is still unclear how these two pathways maintain telomeres. In this study, we performed a genome-wide screen to identify novel genes that are important for the formation of type II ALT-like survivors. We identified 23 genes that disrupt type II survivor formation when deleted. 17 of these genes had not been previously reported to do so. Several of these genes (DUN1, CCR4, and MOT2) are known to be involved in the regulation of dNTP levels. We find that dNTP levels are elevated early after telomerase inactivation and that this increase favors the formation of type II survivors.
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21
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Voichek Y, Mittelman K, Gordon Y, Bar-Ziv R, Lifshitz Smit D, Shenhav R, Barkai N. Epigenetic Control of Expression Homeostasis during Replication Is Stabilized by the Replication Checkpoint. Mol Cell 2018; 70:1121-1133.e9. [PMID: 29910110 DOI: 10.1016/j.molcel.2018.05.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/22/2018] [Accepted: 05/11/2018] [Indexed: 11/24/2022]
Abstract
DNA replication introduces a dosage imbalance between early and late replicating genes. In budding yeast, buffering gene expression against this imbalance depends on marking replicated DNA by H3K56 acetylation (H3K56ac). Whether additional processes are required for suppressing transcription from H3K56ac-labeled DNA remains unknown. Here, using a database-guided candidate screen, we find that COMPASS, the H3K4 methyltransferase, and its upstream effector, PAF1C, act downstream of H3K56ac to buffer expression. Replicated genes show reduced abundance of the transcription activating mark H3K4me3 and accumulate the transcription inhibitory mark H3K4me2 near transcription start sites. Notably, in hydroxyurea-exposed cells, the S phase checkpoint stabilizes H3K56ac and becomes essential for buffering. We suggest that H3K56ac suppresses transcription of replicated genes by interfering with post-replication recovery of epigenetic marks and assign a new function for the S phase checkpoint in stabilizing this mechanism during persistent dosage imbalance.
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Affiliation(s)
- Yoav Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Karin Mittelman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yulia Gordon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raz Bar-Ziv
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David Lifshitz Smit
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rom Shenhav
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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22
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Erpf PE, Fraser JA. The Long History of the Diverse Roles of Short ORFs: sPEPs in Fungi. Proteomics 2018; 18:e1700219. [PMID: 29465163 DOI: 10.1002/pmic.201700219] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 01/30/2018] [Indexed: 12/30/2022]
Abstract
Since the completion of the genome sequence of the model eukaryote Saccharomyces cerevisiae, there have been significant advancements in the field of genome annotation, in no small part due to the availability of datasets that make large-scale comparative analyses possible. As a result, since its completion there has been a significant change in annotated ORF size distribution in this first eukaryotic genome, especially in short ORFs (sORFs) predicted to encode polypeptides less than 150 amino acids in length. Due to their small size and the difficulties associated with their study, it is only relatively recently that these genomic features and the sORF-encoded peptides (sPEPs) they encode have become a focus of many researchers. Yet while this class of peptides may seem new and exciting, the study of this part of the proteome is nothing new in S. cerevisiae, a species where the biological importance of sPEPs has been elegantly illustrated over the past 30 years. Here the authors showcase a range of different sORFs found in S. cerevisiae and the diverse biological roles of their encoded sPEPs, and provide an insight into the sORFs found in other fungal species, particularly those pathogenic to humans.
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Affiliation(s)
- Paige E Erpf
- Australian Infectious Diseases Research Centre, St Lucia, Queensland, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
| | - James A Fraser
- Australian Infectious Diseases Research Centre, St Lucia, Queensland, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
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Ito-Harashima S, Yagi T. Unique molecular mechanisms for maintenance and alteration of genetic information in the budding yeast Saccharomyces cerevisiae. Genes Environ 2017; 39:28. [PMID: 29213342 PMCID: PMC5709847 DOI: 10.1186/s41021-017-0088-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 10/26/2017] [Indexed: 11/10/2022] Open
Abstract
The high-fidelity transmission of genetic information is crucial for the survival of organisms, the cells of which have the ability to protect DNA against endogenous and environmental agents, including reactive oxygen species (ROS), ionizing radiation, and various chemical compounds. The basis of protection mechanisms has been evolutionarily conserved from yeast to humans; however, each organism often has a specialized mode of regulation that uses different sets of machineries, particularly in lower eukaryotes. The divergence of molecular mechanisms among related organisms has provided insights into the evolution of cellular machineries to a higher architecture. Uncommon characteristics of machineries may also contribute to the development of new applications such as drugs with novel mechanisms of action. In contrast to the cellular properties for maintaining genetic information, living organisms, particularly microbes, inevitably undergo genetic alterations in order to adapt to environmental conditions. The maintenance and alteration of genetic information may be inextricably linked to each other. In this review, we describe recent findings on the unconventional molecular mechanisms of DNA damage response and DNA double-strand break (DSB) repair in the budding yeast Saccharomyces cerevisiae. We also introduce our previous research on genetic and phenotypic instabilities observed in a clonal population of clinically-derived S. cerevisiae. The molecular mechanisms of this case were associated with mutations to generate tyrosine-inserting tRNA-Tyr ochre suppressors and the position effects of mutation frequencies among eight tRNA-Tyr loci dispersed in the genome. Phenotypic variations among different strain backgrounds have also been observed by another type of nonsense suppressor, the aberrant form of the translation termination factor. Nonsense suppressors are considered to be responsible for the genome-wide translational readthrough of termination codons, including natural nonsense codons. The nonsense suppressor-mediated acquisition of phenotypic variations may be advantageous for adaptation to environmental conditions and survival during evolution.
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Affiliation(s)
- Sayoko Ito-Harashima
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
| | - Takashi Yagi
- Department of Biological Sciences, Graduate School of Science, Osaka Prefecture University, 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8570 Japan
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Regulation of Small Mitochondrial DNA Replicative Advantage by Ribonucleotide Reductase in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2017; 7:3083-3090. [PMID: 28717049 PMCID: PMC5592933 DOI: 10.1534/g3.117.043851] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Small mitochondrial genomes can behave as selfish elements by displacing wild-type genomes regardless of their detriment to the host organism. In the budding yeast Saccharomyces cerevisiae, small hypersuppressive mtDNA transiently coexist with wild-type in a state of heteroplasmy, wherein the replicative advantage of the small mtDNA outcompetes wild-type and produces offspring without respiratory capacity in >95% of colonies. The cytosolic enzyme ribonucleotide reductase (RNR) catalyzes the rate-limiting step in dNTP synthesis and its inhibition has been correlated with increased petite colony formation, reflecting loss of respiratory function. Here, we used heteroplasmic diploids containing wild-type (rho+) and suppressive (rho−) or hypersuppressive (HS rho−) mitochondrial genomes to explore the effects of RNR activity on mtDNA heteroplasmy in offspring. We found that the proportion of rho+ offspring was significantly increased by RNR overexpression or deletion of its inhibitor, SML1, while reducing RNR activity via SML1 overexpression produced the opposite effects. In addition, using Ex Taq and KOD Dash polymerases, we observed a replicative advantage for small over large template DNA in vitro, but only at low dNTP concentrations. These results suggest that dNTP insufficiency contributes to the replicative advantage of small mtDNA over wild-type and cytosolic dNTP synthesis by RNR is an important regulator of heteroplasmy involving small mtDNA molecules in yeast.
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Normally lethal amino acid substitutions suppress an ultramutator DNA Polymerase δ variant. Sci Rep 2017; 7:46535. [PMID: 28417960 PMCID: PMC5394481 DOI: 10.1038/srep46535] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 03/22/2017] [Indexed: 02/06/2023] Open
Abstract
In yeast, the pol3-01,L612M double mutant allele, which causes defects in DNA polymerase delta (Pol δ) proofreading (pol3-01) and nucleotide selectivity (pol3-L612M), confers an “ultramutator” phenotype that rapidly drives extinction of haploid and diploid MMR-proficient cells. Here, we investigate antimutator mutations that encode amino acid substitutions in Pol δ that suppress this lethal phenotype. We find that most of the antimutator mutations individually suppress the pol3-01 and pol3-L612M mutator phenotypes. The locations of many of the amino acid substitutions in Pol δ resemble those of previously identified antimutator substitutions; however, two novel mutations encode substitutions (R674G and Q697R) of amino acids in the fingers domain that coordinate the incoming dNTP. These mutations are lethal without pol3-L612M and markedly change the mutation spectra produced by the pol3-01,L612M mutator allele, suggesting that they alter nucleotide selection to offset the pol3-L612M mutator phenotype. Consistent with this hypothesis, mutations and drug treatments that perturb dNTP pool levels disproportionately influence the viability of pol3-L612M,R674G and pol3-L612M,Q697R cells. Taken together, our findings suggest that mutation rate can evolve through genetic changes that alter the balance of dNTP binding and dissociation from DNA polymerases.
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Alterations in cellular metabolism triggered by URA7 or GLN3 inactivation cause imbalanced dNTP pools and increased mutagenesis. Proc Natl Acad Sci U S A 2017; 114:E4442-E4451. [PMID: 28416670 DOI: 10.1073/pnas.1618714114] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic DNA replication fidelity relies on the concerted action of DNA polymerase nucleotide selectivity, proofreading activity, and DNA mismatch repair (MMR). Nucleotide selectivity and proofreading are affected by the balance and concentration of deoxyribonucleotide (dNTP) pools, which are strictly regulated by ribonucleotide reductase (RNR). Mutations preventing DNA polymerase proofreading activity or MMR function cause mutator phenotypes and consequently increased cancer susceptibility. To identify genes not previously linked to high-fidelity DNA replication, we conducted a genome-wide screen in Saccharomyces cerevisiae using DNA polymerase active-site mutants as a "sensitized mutator background." Among the genes identified in our screen, three metabolism-related genes (GLN3, URA7, and SHM2) have not been previously associated to the suppression of mutations. Loss of either the transcription factor Gln3 or inactivation of the CTP synthetase Ura7 both resulted in the activation of the DNA damage response and imbalanced dNTP pools. Importantly, these dNTP imbalances are strongly mutagenic in genetic backgrounds where DNA polymerase function or MMR activity is partially compromised. Previous reports have shown that dNTP pool imbalances can be caused by mutations altering the allosteric regulation of enzymes involved in dNTP biosynthesis (e.g., RNR or dCMP deaminase). Here, we provide evidence that mutations affecting genes involved in RNR substrate production can cause dNTP imbalances, which cannot be compensated by RNR or other enzymatic activities. Moreover, Gln3 inactivation links nutrient deprivation to increased mutagenesis. Our results suggest that similar genetic interactions could drive mutator phenotypes in cancer cells.
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27
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Early Loss of Telomerase Action in Yeast Creates a Dependence on the DNA Damage Response Adaptor Proteins. Mol Cell Biol 2016; 36:1908-19. [PMID: 27161319 PMCID: PMC4936065 DOI: 10.1128/mcb.00943-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 04/07/2016] [Indexed: 02/06/2023] Open
Abstract
Telomeres cap the ends of chromosomes, protecting them from degradation and inappropriate DNA repair processes that can lead to genomic instability. A short telomere elicits increased telomerase action on itself that replenishes telomere length, thereby stabilizing the telomere. In the prolonged absence of telomerase activity in dividing cells, telomeres eventually become critically short, inducing a permanent cell cycle arrest (senescence). We recently showed that even early after telomerase inactivation (ETI), yeast cells have accelerated mother cell aging and mildly perturbed cell cycles. Here, we show that the complete disruption of DNA damage response (DDR) adaptor proteins in ETI cells causes severe growth defects. This synthetic-lethality phenotype was as pronounced as that caused by extensive DNA damage in wild-type cells but showed genetic dependencies distinct from such damage and was completely alleviated by SML1 deletion, which increases deoxynucleoside triphosphate (dNTP) pools. Our results indicated that these deleterious effects in ETI cells cannot be accounted for solely by the slow erosion of telomeres due to incomplete replication that leads to senescence. We propose that normally occurring telomeric DNA replication stress is resolved by telomerase activity and the DDR in two parallel pathways and that deletion of Sml1 prevents this stress.
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Misko TA, Wijerathna SR, Radivoyevitch T, Berdis AJ, Ahmad MF, Harris ME, Dealwis CG. Inhibition of yeast ribonucleotide reductase by Sml1 depends on the allosteric state of the enzyme. FEBS Lett 2016; 590:1704-12. [PMID: 27155231 DOI: 10.1002/1873-3468.12207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 04/19/2016] [Accepted: 04/29/2016] [Indexed: 11/05/2022]
Abstract
Sml1 is an intrinsically disordered protein inhibitor of Saccharomyces cerevisiae ribonucleotide reductase (ScRR1), but its inhibition mechanism is poorly understood. RR reduces ribonucleoside diphosphates to their deoxy forms, and balances the nucleotide pool. Multiple turnover kinetics show that Sml1 inhibition of dGTP/ADP- and ATP/CDP-bound ScRR follows a mixed inhibition mechanism. However, Sml1 cooperatively binds to the ES complex in the dGTP/ADP form, whereas with ATP/CDP, Sml1 binds weakly and noncooperatively. Gel filtration and mutagenesis studies indicate that Sml1 does not alter the oligomerization equilibrium and the CXXC motif is not involved in the inhibition. The data suggest that Sml1 is an allosteric inhibitor.
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Affiliation(s)
- Tessianna A Misko
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Sanath R Wijerathna
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Tomas Radivoyevitch
- Department of Quantitative Health Sciences, Cleveland Clinic Foundation, OH, USA
| | | | - Md Faiz Ahmad
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Michael E Harris
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Chris G Dealwis
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
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29
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Wemhoff S, Klassen R, Meinhardt F. DNA damage induced by the anticodon nuclease from a Pichia acaciae killer strain is linked to ribonucleotide reductase depletion. Cell Microbiol 2015; 18:211-22. [PMID: 26247322 DOI: 10.1111/cmi.12496] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/24/2015] [Accepted: 07/26/2015] [Indexed: 11/30/2022]
Abstract
Virus like element (VLE) encoded killer toxins of Pichia acaciae and Kluyveromyces lactis kill target cells through anticodon nuclease (ACNase) activity directed against tRNA(Gln) and tRNA(Glu) respectively. Not only does tRNA cleavage disable translation, it also affects DNA integrity as well. Consistent with DNA damage, which is involved in toxicity, target cells' mutation frequencies are elevated upon ACNase exposure, suggesting a link between translational integrity and genome surveillance. Here, we analysed whether ACNase action impedes the periodically and highly expressed S-phase specific ribonucleotide reductase (RNR) and proved that RNR expression is severely affected by PaT. Because RNR catalyses the rate-limiting step in dNTP synthesis, mutants affected in dNTP synthesis were scrutinized with respect to ACNase action. Mutations elevating cellular dNTPs antagonized the action of both the above ACNases, whereas mutations lowering dNTPs aggravated toxicity. Consistently, prevention of tRNA cleavage in elp3 or trm9 mutants, which both affect the wobble uridine modification of the target tRNA, suppressed the toxin hypersensitivity of a dNTP synthesis mutant. Moreover, dNTP synthesis defects exacerbated the PaT ACNase sensitivity of cells defective in homologous recombination, proving that dNTP depletion is responsible for subsequent DNA damage.
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Affiliation(s)
- Sabrina Wemhoff
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
| | - Roland Klassen
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
| | - Friedhelm Meinhardt
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
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A Single Conserved Residue Mediates Binding of the Ribonucleotide Reductase Catalytic Subunit RRM1 to RRM2 and Is Essential for Mouse Development. Mol Cell Biol 2015; 35:2910-7. [PMID: 26077802 DOI: 10.1128/mcb.00475-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 06/11/2015] [Indexed: 11/20/2022] Open
Abstract
The ribonucleotide reductase (RNR) complex, composed of a catalytic subunit (RRM1) and a regulatory subunit (RRM2), is thought to be a rate-limiting enzymatic complex for the production of nucleotides. In humans, the Rrm1 gene lies at 11p15.5, a tumor suppressor region, and RRM1 expression in cancer has been shown to predict responses to chemotherapy. Nevertheless, whether RRM1 is essential in mammalian cells and what the effects of its haploinsufficiency are remain unknown. To model RNR function in mice we used a mutation previously described in Saccharomyces cerevisiae (Rnr1-W688G) which, despite being viable, leads to increased interaction of the RNR complex with its allosteric inhibitor Sml1. In contrast to yeast, homozygous mutant mice carrying the Rrm1 mutation (Rrm1(WG/WG)) are not viable, even at the earliest embryonic stages. Proteomic analyses failed to identify proteins that specifically bind to the mutant RRM1 but revealed that, in mammals, the mutation prevents RRM1 binding to RRM2. Despite the impact of the mutation, Rrm1(WG/+) mice and cells presented no obvious phenotype, suggesting that the RRM1 protein exists in excess. Our work reveals that binding of RRM1 to RRM2 is essential for mammalian cells and provides the first loss-of-function model of the RNR complex for genetic studies.
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Mec1-dependent phosphorylation of Mms21 modulates its SUMO ligase activity. DNA Repair (Amst) 2015; 28:83-92. [DOI: 10.1016/j.dnarep.2015.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 12/25/2022]
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dNTP pool levels modulate mutator phenotypes of error-prone DNA polymerase ε variants. Proc Natl Acad Sci U S A 2015; 112:E2457-66. [PMID: 25827226 DOI: 10.1073/pnas.1422948112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutator phenotypes create genetic diversity that fuels tumor evolution. DNA polymerase (Pol) ε mediates leading strand DNA replication. Proofreading defects in this enzyme drive a number of human malignancies. Here, using budding yeast, we show that mutator variants of Pol ε depend on damage uninducible (Dun)1, an S-phase checkpoint kinase that maintains dNTP levels during a normal cell cycle and up-regulates dNTP synthesis upon checkpoint activation. Deletion of DUN1 (dun1Δ) suppresses the mutator phenotype of pol2-4 (encoding Pol ε proofreading deficiency) and is synthetically lethal with pol2-M644G (encoding altered Pol ε base selectivity). Although pol2-4 cells cycle normally, pol2-M644G cells progress slowly through S-phase. The pol2-M644G cells tolerate deletions of mediator of the replication checkpoint (MRC) 1 (mrc1Δ) and radiation sensitive (Rad) 9 (rad9Δ), which encode mediators of checkpoint responses to replication stress and DNA damage, respectively. The pol2-M644G mutator phenotype is partially suppressed by mrc1Δ but not rad9Δ; neither deletion suppresses the pol2-4 mutator phenotype. Thus, checkpoint activation augments the Dun1 effect on replication fidelity but is not required for it. Deletions of genes encoding key Dun1 targets that negatively regulate dNTP synthesis, suppress the dun1Δ pol2-M644G synthetic lethality and restore the mutator phenotype of pol2-4 in dun1Δ cells. DUN1 pol2-M644G cells have constitutively high dNTP levels, consistent with checkpoint activation. In contrast, pol2-4 and POL2 cells have similar dNTP levels, which decline in the absence of Dun1 and rise in the absence of the negative regulators of dNTP synthesis. Thus, dNTP pool levels correlate with Pol ε mutator severity, suggesting that treatments targeting dNTP pools could modulate mutator phenotypes for therapy.
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Lodi T, Dallabona C, Nolli C, Goffrini P, Donnini C, Baruffini E. DNA polymerase γ and disease: what we have learned from yeast. Front Genet 2015; 6:106. [PMID: 25852747 PMCID: PMC4362329 DOI: 10.3389/fgene.2015.00106] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/02/2015] [Indexed: 11/16/2022] Open
Abstract
Mip1 is the Saccharomyces cerevisiae DNA polymerase γ (Pol γ), which is responsible for the replication of mitochondrial DNA (mtDNA). It belongs to the family A of the DNA polymerases and it is orthologs to human POLGA. In humans, mutations in POLG(1) cause many mitochondrial pathologies, such as progressive external ophthalmoplegia (PEO), Alpers' syndrome, and ataxia-neuropathy syndrome, all of which present instability of mtDNA, which results in impaired mitochondrial function in several tissues with variable degrees of severity. In this review, we summarize the genetic and biochemical knowledge published on yeast mitochondrial DNA polymerase from 1989, when the MIP1 gene was first cloned, up until now. The role of yeast is particularly emphasized in (i) validating the pathological mutations found in human POLG and modeled in MIP1, (ii) determining the molecular defects caused by these mutations and (iii) finding the correlation between mutations/polymorphisms in POLGA and mtDNA toxicity induced by specific drugs. We also describe recent findings regarding the discovery of molecules able to rescue the phenotypic defects caused by pathological mutations in Mip1, and the construction of a model system in which the human Pol γ holoenzyme is expressed in yeast and complements the loss of Mip1.
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Affiliation(s)
- Tiziana Lodi
- Department of Life Sciences, University of Parma Parma, Italy
| | | | - Cecilia Nolli
- Department of Life Sciences, University of Parma Parma, Italy
| | - Paola Goffrini
- Department of Life Sciences, University of Parma Parma, Italy
| | - Claudia Donnini
- Department of Life Sciences, University of Parma Parma, Italy
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Loss of APD1 in yeast confers hydroxyurea sensitivity suppressed by Yap1p transcription factor. Sci Rep 2015; 5:7897. [PMID: 25600293 PMCID: PMC4298746 DOI: 10.1038/srep07897] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/16/2014] [Indexed: 01/01/2023] Open
Abstract
Ferredoxins are iron-sulfur proteins that play important roles in electron transport and redox homeostasis. Yeast Apd1p is a novel member of the family of thioredoxin-like ferredoxins. In this study, we characterized the hydroxyurea (HU)-hypersensitive phenotype of apd1Δ cells. HU is an inhibitor of DNA synthesis, a cellular stressor and an anticancer agent. Although the loss of APD1 did not influence cell proliferation or cell cycle progression, it resulted in HU sensitivity. This sensitivity was reverted in the presence of antioxidant N-acetyl-cysteine, implicating a role for intracellular redox. Mutation of the iron-binding motifs in Apd1p abrogated its ability to rescue HU sensitivity in apd1Δ cells. The iron-binding activity of Apd1p was verified by a color assay. By mass spectrometry two irons were found to be incorporated into one Apd1p protein molecule. Surprisingly, ribonucleotide reductase genes were not induced in apd1Δ cells and the HU sensitivity was unaffected when dNTP production was boosted. A suppressor screen was performed and the expression of stress-regulated transcription factor Yap1p was found to effectively rescue the HU sensitivity in apd1Δ cells. Taken together, our work identified Apd1p as a new ferredoxin which serves critical roles in cellular defense against HU.
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Meurisse J, Bacquin A, Richet N, Charbonnier JB, Ochsenbein F, Peyroche A. Hug1 is an intrinsically disordered protein that inhibits ribonucleotide reductase activity by directly binding Rnr2 subunit. Nucleic Acids Res 2014; 42:13174-85. [PMID: 25378334 PMCID: PMC4245953 DOI: 10.1093/nar/gku1095] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rad53 is a conserved protein kinase with a central role in DNA damage response and nucleotide metabolism. We observed that the expression of a dominant-lethal form of RAD53 leads to significant expression changes for at least 16 genes, including the RNR3 and the HUG1 genes, both of which are involved in the control of nucleotide metabolism. We established by multiple biophysical and biochemical approaches that Hug1 is an intrinsically disordered protein that directly binds to the small RNR subunit Rnr2. We characterized the surface of interaction involved in Hug1 binding to Rnr2, and we thus defined a new binding region to Rnr2. Moreover, we show that Hug1 is deleterious to cell growth in the context of reduced RNR activity. This inhibitory effect of Hug1 on RNR activity depends on the binding of Hug1 to Rnr2. We propose a model in which Hug1 modulates Rnr2-Rnr1 association by binding Rnr2. We show that Hug1 accumulates under various physiological conditions of high RNR induction. Hence, both the regulation and the mode of action of Hug1 are different from those of the small protein inhibitors Dif1 and Sml1, and Hug1 can be considered as a regulator for fine-tuning of RNR activity.
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Affiliation(s)
- Julie Meurisse
- CEA, iBiTecS, SBIGeM, Gif-sur-Yvette, F-91191, France CNRS-Université Paris Sud, FRE 3377, Gif-sur-Yvette, F-91191, France
| | - Agathe Bacquin
- CEA, iBiTecS, SBIGeM, Gif-sur-Yvette, F-91191, France CNRS-Université Paris Sud, FRE 3377, Gif-sur-Yvette, F-91191, France
| | - Nicolas Richet
- CEA, iBiTecS, SBSM, Laboratoire de Biologie Structurale et Radiobiologie, Gif-sur-Yvette, F-91191, France CNRS, UMR8221, Gif-sur-Yvette, F-91191, France
| | - Jean-Baptiste Charbonnier
- CEA, iBiTecS, SBSM, Laboratoire de Biologie Structurale et Radiobiologie, Gif-sur-Yvette, F-91191, France CNRS, UMR8221, Gif-sur-Yvette, F-91191, France
| | - Françoise Ochsenbein
- CEA, iBiTecS, SBSM, Laboratoire de Biologie Structurale et Radiobiologie, Gif-sur-Yvette, F-91191, France CNRS, UMR8221, Gif-sur-Yvette, F-91191, France
| | - Anne Peyroche
- CEA, iBiTecS, SBIGeM, Gif-sur-Yvette, F-91191, France CNRS-Université Paris Sud, FRE 3377, Gif-sur-Yvette, F-91191, France
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Arnaoutov A, Dasso M. Enzyme regulation. IRBIT is a novel regulator of ribonucleotide reductase in higher eukaryotes. Science 2014; 345:1512-5. [PMID: 25237103 DOI: 10.1126/science.1251550] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ribonucleotide reductase (RNR) supplies the balanced pools of deoxynucleotide triphosphates (dNTPs) necessary for DNA replication and maintenance of genomic integrity. RNR is subject to allosteric regulatory mechanisms in all eukaryotes, as well as to control by small protein inhibitors Sml1p and Spd1p in budding and fission yeast, respectively. Here, we show that the metazoan protein IRBIT forms a deoxyadenosine triphosphate (dATP)-dependent complex with RNR, which stabilizes dATP in the activity site of RNR and thus inhibits the enzyme. Formation of the RNR-IRBIT complex is regulated through phosphorylation of IRBIT, and ablation of IRBIT expression in HeLa cells causes imbalanced dNTP pools and altered cell cycle progression. We demonstrate a mechanism for RNR regulation in higher eukaryotes that acts by enhancing allosteric RNR inhibition by dATP.
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Affiliation(s)
- Alexei Arnaoutov
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Mary Dasso
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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Yeast Dun1 kinase regulates ribonucleotide reductase inhibitor Sml1 in response to iron deficiency. Mol Cell Biol 2014; 34:3259-71. [PMID: 24958100 DOI: 10.1128/mcb.00472-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox-active cofactor in many biological processes, including DNA replication and repair. Eukaryotic ribonucleotide reductases (RNRs) are Fe-dependent enzymes that catalyze deoxyribonucleoside diphosphate (dNDP) synthesis. We show here that the levels of the Sml1 protein, a yeast RNR large-subunit inhibitor, specifically decrease in response to both nutritional and genetic Fe deficiencies in a Dun1-dependent but Mec1/Rad53- and Aft1-independent manner. The decline of Sml1 protein levels upon Fe starvation depends on Dun1 forkhead-associated and kinase domains, the 26S proteasome, and the vacuolar proteolytic pathway. Depletion of core components of the mitochondrial iron-sulfur cluster assembly leads to a Dun1-dependent diminution of Sml1 protein levels. The physiological relevance of Sml1 downregulation by Dun1 under low-Fe conditions is highlighted by the synthetic growth defect observed between dun1Δ and fet3Δ fet4Δ mutants, which is rescued by SML1 deletion. Consistent with an increase in RNR function, Rnr1 protein levels are upregulated upon Fe deficiency. Finally, dun1Δ mutants display defects in deoxyribonucleoside triphosphate (dNTP) biosynthesis under low-Fe conditions. Taken together, these results reveal that the Dun1 checkpoint kinase promotes RNR function in response to Fe starvation by stimulating Sml1 protein degradation.
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Guarino E, Salguero I, Kearsey SE. Cellular regulation of ribonucleotide reductase in eukaryotes. Semin Cell Dev Biol 2014; 30:97-103. [PMID: 24704278 DOI: 10.1016/j.semcdb.2014.03.030] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 03/26/2014] [Indexed: 12/22/2022]
Abstract
Synthesis of deoxynucleoside triphosphates (dNTPs) is essential for both DNA replication and repair and a key step in this process is catalyzed by ribonucleotide reductases (RNRs), which reduce ribonucleotides (rNDPs) to their deoxy forms. Tight regulation of RNR is crucial for maintaining the correct levels of all four dNTPs, which is important for minimizing the mutation rate and avoiding genome instability. Although allosteric control of RNR was the first discovered mechanism involved in regulation of the enzyme, other controls have emerged in recent years. These include regulation of expression of RNR genes, proteolysis of RNR subunits, control of the cellular localization of the small RNR subunit, and regulation of RNR activity by small protein inhibitors. This review will focus on these additional mechanisms of control responsible for providing a balanced supply of dNTPs.
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Affiliation(s)
- Estrella Guarino
- Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
| | - Israel Salguero
- Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
| | - Stephen E Kearsey
- Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
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Lebovka IY, Kozhina TN, Fedorova IV, Peshekhonov VT, Evstyukhina TA, Chernenkov AY, Korolev VG. Sin3 histone deacetylase controls level of spontaneous and UV-induced mutagenesis in yeast Saccharomyces cerevisiae. RUSS J GENET+ 2014. [DOI: 10.1134/s1022795413110124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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40
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Fleck O, Vejrup-Hansen R, Watson A, Carr AM, Nielsen O, Holmberg C. Spd1 accumulation causes genome instability independently of ribonucleotide reductase activity but functions to protect the genome when deoxynucleotide pools are elevated. J Cell Sci 2013; 126:4985-94. [PMID: 23986475 DOI: 10.1242/jcs.132837] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cullin4, Ddb1 and Cdt2 are core subunits of the ubiquitin ligase complex CRL4(Cdt2), which controls genome stability by targeting Spd1 for degradation during DNA replication and repair in fission yeast. Spd1 has an inhibitory effect on ribonucleotide reductase (RNR), the activity of which is required for deoxynucleotide (dNTP) synthesis. The failure to degrade Spd1 in mutants where CRL4(Cdt2) is defective leads to DNA integrity checkpoint activation and dependency. This correlates with a lower dNTP pool. Pools are restored in a spd1-deleted background and this also suppresses checkpoint activation and dependency. We hypothesized that fission yeast with RNR hyperactivity would display a mutator phenotype on their own, but also possibly repress aspects of the phenotype associated with the inability to target Spd1 for degradation. Here, we report that a mutation in the R1 subunit of ribonucleotide reductase cdc22 (cdc22-D57N), which alleviated allosteric feedback inhibition, caused a highly elevated dNTP pool that was further increased by deleting spd1. The Δspd1 cdc22-D57N double mutant had elevated mutation rates and was sensitive to damaging agents that cause DNA strand breaks, demonstrating that Spd1 can protect the genome when dNTP pools are high. In ddb1-deleted cells, cdc22-D57N also potently elevated RNR activity, but failed to allow cell growth independently of the intact checkpoint. Our results provide evidence that excess Spd1 interferes with other functions in addition to its inhibitory effect on ribonucleotide reduction to generate replication stress and genome instability.
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Affiliation(s)
- Oliver Fleck
- Cell Cycle and Genome Stability Group, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark
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Jossen R, Bermejo R. The DNA damage checkpoint response to replication stress: A Game of Forks. Front Genet 2013; 4:26. [PMID: 23493417 PMCID: PMC3595514 DOI: 10.3389/fgene.2013.00026] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 02/18/2013] [Indexed: 12/23/2022] Open
Abstract
Conditions challenging replication fork progression, collectively referred to as replication stress, represent a major source of genomic instability and are associated to cancer onset. The replication checkpoint, a specialized branch of the DNA damage checkpoint, monitors fork problems, and triggers a cellular response aimed at preserving genome integrity. Here, we review the mechanisms by which the replication checkpoint monitors and responds to replication stress, focusing on the checkpoint-mediated pathways contributing to protect replication fork integrity. We discuss how cells achieve checkpoint signaling inactivation once replication stress is overcome and how a failure to timely revert checkpoint-mediated changes in cellular physiology might impact on replication dynamics and genome integrity. We also highlight the checkpoint function as an anti-cancer barrier preventing cells malignant transformation following oncogene-induced replication stress.
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Affiliation(s)
- Rachel Jossen
- Instituto de Biología Funcional y Genómica, CSIC/USAL Salamanca, Spain
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42
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Abstract
Telomeres, the ends of linear eukaryotic chromosomes, shorten due to incomplete DNA replication and nucleolytic degradation. Cells counteract this shortening by employing a specialized reverse transcriptase called telomerase, which uses deoxyribonucleoside triphosphates (dNTPs) to extend telomeres. Intracellular dNTP levels are tightly regulated, and perturbation of these levels is known to affect DNA synthesis. We examined whether altering the levels of the dNTP pools or changing the relative ratios of the four dNTPs in Saccharomyces cerevisiae would affect the length of the telomeres. Lowering dNTP levels leads to a modest shortening of telomeres, while increasing dNTP pools has no significant effect on telomere length. Strikingly, altering the ratio of the four dNTPs dramatically affects telomere length homeostasis, both positively and negatively. Specifically, we find that intracellular deoxyguanosine triphosphate (dGTP) levels positively correlate with both telomere length and telomerase nucleotide addition processivity in vivo. Our findings are consistent with in vitro data showing dGTP-dependent stimulation of telomerase activity in multiple organisms and suggest that telomerase activity is modulated in vivo by dGTP levels.
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Baek IJ, Kang HJ, Chang M, Choi ID, Kang CM, Yun CW. Cadmium inhibits the protein degradation of Sml1 by inhibiting the phosphorylation of Sml1 in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2012; 424:385-90. [PMID: 22771327 DOI: 10.1016/j.bbrc.2012.06.103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 06/20/2012] [Indexed: 12/17/2022]
Abstract
Cadmium is a toxic metal, and the mechanism of cadmium toxicity in living organisms has been well studied. Here, we used Saccharomyces cerevisiae as a model system to examine the detailed molecular mechanism of cell growth defects caused by cadmium. Using a plate assay of a yeast deletion mutant collection, we found that deletion of SML1, which encodes an inhibitor of Rnr1, resulted in cadmium resistance. Sml1 protein levels increased when cells were treated with cadmium, even though the mRNA levels of SML1 remained unchanged. Using northern and western blot analyses, we found that cadmium inhibited Sml1 degradation by inhibiting Sml1 phosphorylation. Sml1 protein levels increased when cells were treated with cadmium due to disruption of the dependent protein degradation pathway. Furthermore, cadmium promoted cell cycle progression into the G2 phase. The same result was obtained using cells in which SML1 was overexpressed. Deletion of SML1 delayed cell cycle progression. These results are consistent with Sml1 accumulation and with growth defects caused by cadmium stress. Interestingly, although cadmium treatment led to increase Sml1 levels, intracellular dNTP levels also increased because of Rnr3 upregulation due to cadmium stress. Taken together, these results suggest that cadmium specifically affects the phosphorylation of Sml1 and that Sml1 accumulates in cells.
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Affiliation(s)
- In-Joon Baek
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul, Republic of Korea
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Role of arginine 293 and glutamine 288 in communication between catalytic and allosteric sites in yeast ribonucleotide reductase. J Mol Biol 2012; 419:315-29. [PMID: 22465672 DOI: 10.1016/j.jmb.2012.03.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 03/15/2012] [Accepted: 03/17/2012] [Indexed: 02/05/2023]
Abstract
Ribonucleotide reductases (RRs) catalyze the rate-limiting step of de novo deoxynucleotide (dNTP) synthesis. Eukaryotic RRs consist of two proteins, RR1 (α) that contains the catalytic site and RR2 (β) that houses a diferric-tyrosyl radical essential for ribonucleoside diphosphate reduction. Biochemical analysis has been combined with isothermal titration calorimetry (ITC), X-ray crystallography and yeast genetics to elucidate the roles of two loop 2 mutations R293A and Q288A in Saccharomyces cerevisiae RR1 (ScRR1). These mutations, R293A and Q288A, cause lethality and severe S phase defects, respectively, in cells that use ScRR1 as the sole source of RR1 activity. Compared to the wild-type enzyme activity, R293A and Q288A mutants show 4% and 15%, respectively, for ADP reduction, whereas they are 20% and 23%, respectively, for CDP reduction. ITC data showed that R293A ScRR1 is unable to bind ADP and binds CDP with 2-fold lower affinity compared to wild-type ScRR1. With the Q288A ScRR1 mutant, there is a 6-fold loss of affinity for ADP binding and a 2-fold loss of affinity for CDP compared to the wild type. X-ray structures of R293A ScRR1 complexed with dGTP and AMPPNP-CDP [AMPPNP, adenosine 5-(β,γ-imido)triphosphate tetralithium salt] reveal that ADP is not bound at the catalytic site, and CDP binds farther from the catalytic site compared to wild type. Our in vivo functional analyses demonstrated that R293A cannot support mitotic growth, whereas Q288A can, albeit with a severe S phase defect. Taken together, our structure, activity, ITC and in vivo data reveal that the arginine 293 and glutamine 288 residues of ScRR1 are crucial in facilitating ADP and CDP substrate selection.
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Sanvisens N, Bañó MC, Huang M, Puig S. Regulation of ribonucleotide reductase in response to iron deficiency. Mol Cell 2012; 44:759-69. [PMID: 22152479 DOI: 10.1016/j.molcel.2011.09.021] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 08/09/2011] [Accepted: 09/10/2011] [Indexed: 11/17/2022]
Abstract
Ribonucleotide reductase (RNR) is an essential enzyme required for DNA synthesis and repair. Although iron is necessary for class Ia RNR activity, little is known about the mechanisms that control RNR in response to iron deficiency. In this work, we demonstrate that yeast cells control RNR function during iron deficiency by redistributing the Rnr2-Rnr4 small subunit from the nucleus to the cytoplasm. Our data support a Mec1/Rad53-independent mechanism in which the iron-regulated Cth1/Cth2 mRNA-binding proteins specifically interact with the WTM1 mRNA in response to iron scarcity and promote its degradation. The resulting decrease in the nuclear-anchoring Wtm1 protein levels leads to the redistribution of the Rnr2-Rnr4 heterodimer to the cytoplasm, where it assembles as an active RNR complex and increases deoxyribonucleoside triphosphate levels. When iron is scarce, yeast selectively optimizes RNR function at the expense of other non-essential iron-dependent processes that are repressed, to allow DNA synthesis and repair.
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Affiliation(s)
- Nerea Sanvisens
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, Consejo Superior de Investigaciones Científicas, Burjassot, Valencia 46100, Spain
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Azad GK, Balkrishna SJ, Sathish N, Kumar S, Tomar RS. Multifunctional Ebselen drug functions through the activation of DNA damage response and alterations in nuclear proteins. Biochem Pharmacol 2012; 83:296-303. [DOI: 10.1016/j.bcp.2011.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/12/2011] [Accepted: 10/12/2011] [Indexed: 11/27/2022]
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Targeting the Large Subunit of Human Ribonucleotide Reductase for Cancer Chemotherapy. Pharmaceuticals (Basel) 2011; 4:1328-1354. [PMID: 23115527 PMCID: PMC3483043 DOI: 10.3390/ph4101328] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ribonucleotide reductase (RR) is a crucial enzyme in de novo DNA synthesis, where it catalyses the rate determining step of dNTP synthesis. RRs consist of a large subunit called RR1 (α), that contains two allosteric sites and one catalytic site, and a small subunit called RR2 (β), which houses a tyrosyl free radical essential for initiating catalysis. The active form of mammalian RR is an αnβm hetero oligomer. RR inhibitors are cytotoxic to proliferating cancer cells. In this brief review we will discuss the three classes of RR, the catalytic mechanism of RR, the regulation of the dNTP pool, the substrate selection, the allosteric activation, inactivation by ATP and dATP, and the nucleoside drugs that target RR. We will also discuss possible strategies for developing a new class of drugs that disrupts the RR assembly.
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Kwan EX, Foss E, Kruglyak L, Bedalov A. Natural polymorphism in BUL2 links cellular amino acid availability with chronological aging and telomere maintenance in yeast. PLoS Genet 2011; 7:e1002250. [PMID: 21901113 PMCID: PMC3161923 DOI: 10.1371/journal.pgen.1002250] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 07/06/2011] [Indexed: 12/21/2022] Open
Abstract
Aging and longevity are considered to be highly complex genetic traits. In order to gain insight into aging as a polygenic trait, we employed an outbred Saccharomyces cerevisiae model, generated by crossing a vineyard strain RM11 and a laboratory strain S288c, to identify quantitative trait loci that control chronological lifespan. Among the major loci that regulate chronological lifespan in this cross, one genetic linkage was found to be congruent with a previously mapped locus that controls telomere length variation. We found that a single nucleotide polymorphism in BUL2, encoding a component of an ubiquitin ligase complex involved in trafficking of amino acid permeases, controls chronological lifespan and telomere length as well as amino acid uptake. Cellular amino acid availability changes conferred by the BUL2 polymorphism alter telomere length by modulating activity of a transcription factor Gln3. Among the GLN3 transcriptional targets relevant to this phenotype, we identified Wtm1, whose upregulation promotes nuclear retention of ribonucleotide reductase (RNR) components and inhibits the assembly of the RNR enzyme complex during S-phase. Inhibition of RNR is one of the mechanisms by which Gln3 modulates telomere length. Identification of a polymorphism in BUL2 in this outbred yeast population revealed a link among cellular amino acid availability, chronological lifespan, and telomere length control.
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Affiliation(s)
- Elizabeth X. Kwan
- Clinical Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology Program, University of Washington and Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Eric Foss
- Clinical Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Leonid Kruglyak
- Lewis-Sigler Institute for Integrative Genomics and Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Antonio Bedalov
- Clinical Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology Program, University of Washington and Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Kozhina TN, Kozhin SA, Korolev VG. Gene RAD31 is identical to gene MEC1 of yeast Saccharomyces cerevisiae. RUSS J GENET+ 2011. [DOI: 10.1134/s1022795411020104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Holmgren A, Sengupta R. The use of thiols by ribonucleotide reductase. Free Radic Biol Med 2010; 49:1617-28. [PMID: 20851762 DOI: 10.1016/j.freeradbiomed.2010.09.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 08/17/2010] [Accepted: 09/03/2010] [Indexed: 12/22/2022]
Abstract
Ribonucleotide reductase (RNR) catalyzes the rate-limiting de novo synthesis of 2'-deoxyribonucleotides from the corresponding ribonucleotides and thereby provides balanced deoxyribonucleotide pools required for error-free DNA replication and repair. The essential role of RNR in DNA synthesis and the use of DNA as genetic material has made it an important target for the development of anticancer and antiviral agents. The most well known feature of the universal RNR reaction in all kingdoms of life is the involvement of protein free radicals. Redox-active cysteines, thiyl radicals, and thiol redox proteins of the thioredoxin superfamily play major roles in the catalytic mechanism. The involvement of cysteine residues in catalysis is common to all three classes of RNR. Taking account of the recent progress in this field of research, this review focuses on the use of thiols in the redox mechanism of RNR enzymes.
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Affiliation(s)
- Arne Holmgren
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
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