DOCSLIB.ORG

Defining Error-Free Postreplication Repair in Saccharomyces Cerevisiae

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Defining Error-Free Postreplication Repair in Saccharomyces Cerevisiae Defining Error-Free Postreplication Repair In Saccharomyces cerevisiae A thesis submitted to the College of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Microbiology and Immuriology University of Saskatchewan Stacey D. Broomfield, B.Sc. Winter 2000 O Copyright Stacey D. Broornfield, 2000. Al1 rights reserved. National Library Bibliothèque nationale 1+1 of Canada du Canada Acquisitions and Acquisitions et Bibliographic Se~ices services bibliographiques 395 Wellington çtreet 395, nie Wellington Ottawa ON KIA ON4 Ottawa ON K1A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence aIlowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or elertronic formats. la forme de microfiche/fFlm, de reproduction sur papier ou sur foxmat électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Permission To Use In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, 1agree that the Libraries of this University may make it freely available for inspection. 1further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or make other use of material in this thesis in whole or in part should be addressed to: Head of the Department of Microbiology and Immunology Health Science Building, 107 Wiggins Road, University of Saskatchewan Saskatoon, Saskatchewan Canada S7N 5E5 Abstract The mms2-1 yeast mutant was isolated by its sensitivity to the DNA alkylating agent methyl methanesulfonate (MMS) as part of a screen to identify genes respowible for repair of DNA alkylation damage. 1 cloned the MMS2 gene by complementation of the mms2-1 mutant for MMS sensitivity and determined its nucleotide sequence. The deduced Mms2 protein shares strong sequence similarity with ubiquitin-conjugating enzymes (Ubcs), but Mms2 lacks in vitro Ubc activity. Unlike the original mms2-l mutant, which is only sensitive to MMS, the mms2 disruption mutant displays sensitivity to both MMS and UV radiation. Another Ubc mutant that displays both UV and MMS sensitivity is ubc2/rad6 which is essential for both postreplication repair (PRR) and muhgenesis. DNA damage that blocks normal replication is lethal. PRR is a mechanism that allows replication to proceed in the presence of damage and for repair to be effected thereafter. The rad6 and rad18 mutations are epistatic to mms2, suggesting that MMSZ functions in the RAD6 pathway. Interestingly, the mms2 mutation increases both spontaneous and UV-induced mutagenesis, is synergistic with rev3 for UV and MMS sensitivity, and its mutagenesis effect is completely dependent on the REV3 gene. Based on these observations, it is proposed that MMSZ plays a role in error-free PRR parallel to REV3-mediated mutagenesis within the RAD6 pathway. Rad6 has many cellular functions that are not related to PRil, i~ciudkg telomeric silencing, sporulation and protein degradation. To determine whether or not Mms2 functions as an accessory protein for Rad6 or if it is specific for PRR, 1 tested the effect of the mms2 mutation on each of the above cellular processes. mms2 displayed a moderate defect in sporulation, with a minor effect on protein degradation and no effect on teelomeric silencing. Hence, 1 have determined that Mms2 is involved in error-free PRR, but its role in other Rad6 mediated processes is yet to be determined. Several proteins or domains, including PCNA (Po130), Rad30, Rad5 and the N-terminus of Rad6, are irnplicated in the error-free PRR pathway. We perfomed epistasis analysis to ask whether or not these genes and mms2 act in the same error-free subpathway. None of the above mutations exhibited epis ta tic rela tionships, indica ting tha t the gene tic interactions among these genes are complica ted. The SRS2 gene encodes a helicase whose exact function is unknown. Alleles of srs2 were identified based on their ability to suppress the extreme UV and MMS sensitivity of rad6 and rad18 mutants. 1 wanted to assess the effect of the srs2 nul1 mutation on the various mutants defective in PRR. 1 found that sr52 is epistatic to al1 PRR mutations, regardless of error-free and error-prone involvement, since the srs2 mutation was able to suppress the MMS sensitivities of po130-46, rad5, pol30-46 rad5, rad30, mms2 and rev3. These genetic relationships indicate that the PRR pathway is dependent upon the unknown activity of the Srs2 helicase. Two human homologues of MMS2 were isolated. CROC-IS was isolated due to its ability to transactivate the c-fos promoter. hMMS2 was isolated in a homology screen using the deduced Mms2 sequence. The 145 amino acid iii cDNA clone shares 50.4% sequence identity to Mrns2. Since sequence homology alone cannot determine if the two enzymes evolved with similar functions, 1 cioned hMMS2 under the conhol of a yeast inducible promoter and introduced it into a mms2 mutant to assay for functional complementation. hMMS was able to complernent the MM5 and UV sensitivities, as well as mutator phenotypes of the mms2 mutant. CROC-1B is unable to complement any of the mms2 defects, unless its N-terminal domain is removed. My research with yeast and hurnan MMS2 has helped to clariQ the PRR pathway and to define a novel Ubc-like protein family. This study also aided the recent advances in the biochemistry of a novel Ubcl3-Mms2 complex formation, its unique ubiquitin chah assembly and its interactions with RING finger proteins. In addition, discoveries made in this study have stimulated Our laboratory as well as other laboratories to focus on the roles of the Ubcl3-Mms2 complex in human diseases and cancer. IiMMS2 and CROC4 have been implicated in the progression of cells from a pre-immortal to immortal state, in cellular differentiation, in tumorigenesis and in error-free PRR. Further investigations of this complex may prove to be useful in cancer prevention and therap y. Acknowledgments 1would like to begin by thanking my supervisor, Dr. Wei Xiao. Dr. Xiao has provided a supportive learning environment and invaluable guidance during a very busy time in his career. His devotion, enthusiasm and encouragement has been a motivating force throughout my studies, and is greatly appreciated. 1would also like to thank the members of my supewisory cornmittee, Dr. Susan Laferte, Dr. Hamy Deneer, and Dr. Sean Hernmingsen, for offering support and advice. A special thanks to Dr. Dan Gietz, my extemal examiner from the University of Manitoba. Dr. Gietz was a wonderful addition to my defense proceedings. A very important thank-you is extended to the people in the laboratory of Dr. Xiao. Our laboratory has always contained talented individuals that are a pleasure to work with. Thanks to Treena Swanston, Barbara Chow, Todd Hryciw, Mahmood Chamankhah, Yule Liu, Janelle Franko, Sonya Bawa, Carolyn Ashley, Leslie Sarbour, Landon Pastushok, Yu Zhu, Parker Anderson and Michelle Hama, for making the workplace fun. 1must Say a special thank- you to Todd Hryciw, colleague and friend. Todd is a friend with whom 1 shared excitement, frustration, laughs, ideas, and al1 the trivial problems life offers. 1greatly appreciate the financial support provided by College of Medicine Graduate scholarships and the University of Saskatchewan Graduate scholarships. Finally, 1must thank my family. Thank you for your self-less cornmitment, patience and unconditional love. My gratitude camot be expressed in words. Table of Contents: PERMISSION TO USE ABSTRACT ACKNOWLEDGMENTS DEDICATION TABLE OF CONTENTS vii LIST OF TABLES LIST OF FIGURES xii LIST OF ABBREVIATIONS xiv CHAPTER ONE: INTRODUCTION 1.1. Protecting Our Genome. 1.2. DNA Damage. 1.2.1. DNA Damage. 1.2.2. DNA Damage: Biological Consequences. 1.2.3. Endogenous DNA Damage. 1.2.4. Environmental DNA Damaging Agents. 1.2.4.l. Physical Agents. 1.2.4.2. Chernical Agents. 1.3. How the CeIl Copes with DNA Damage. 1.3.1. Ce11 Cycle Controls. 1.3.2. DNA Damage Repair. 1.4. DNA Repair Pathways. 1.4.1. Direct Reversa1 Of DNA Damage. 1.4.2. Excision Of DNA Damage. 1.4.2.1. Base Excision Repair. 1.4.2.2. Nucleotide Excision Repair. 1.4.3. Recombina tion Repair. 1.5. DNA Darnage Tolerance. 1.5.1. SOS Response Ln E. coli 1.5.2. Postreplication Repair in Eukaryotes 1.6. Postreplication Repair In Saccharomyces cerevisiae 1.6.1. Recombination Repair In DNA Damage Tolerance 1.6.2. Assessing The Genes Comprising PRR. vii 1.6.2.1. RAD6-RAD18 Cornplex: DNA Damage Recognition? 36 1.6.2.2. Rad6: A Ubiquitin-conjugating Enzyme.
Load more

Recommended publications
  • The Role of Nucleotide Excision Repair in Restoring Replication Following UV-Induced Damage in Escherichia Coli
    Portland State University PDXScholar Dissertations and Theses Dissertations and Theses Summer 1-1-2012 The Role of Nucleotide Excision Repair in Restoring Replication Following UV-Induced Damage in Escherichia coli Kelley Nicole Newton Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Biology Commons, and the Cell Biology Commons Let us know how access to this document benefits ou.y Recommended Citation Newton, Kelley Nicole, "The Role of Nucleotide Excision Repair in Restoring Replication Following UV- Induced Damage in Escherichia coli" (2012). Dissertations and Theses. Paper 767. https://doi.org/10.15760/etd.767 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. The Role of Nucleotide Excision Repair in Restoring Replication Following UV-Induced Damage in Escherichia coli by Kelley Nicole Newton A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology Thesis Committee: Justin Courcelle, Chair Michael Bartlett Jeffrey Singer Portland State University 2012 ABSTRACT Following low levels of UV exposure, Escherichia coli cells deficient in nucleotide excision repair recover and synthesize DNA at near wild type levels, an observation that formed the basis of the post replication recombination repair model. In this study, we characterized the DNA synthesis that occurs following UV-irradiation in the absence of nucleotide excision repair and show that although this synthesis resumes at near wild type levels, it is coincident with a high degree of cell death.
    [Show full text]
  • Fission Yeast Hsk1 (Cdc7) Kinase Is Required After Replication Initiation for Induced Mutagenesis and Proper Response to DNA Alkylation Damage
    Copyright Ó 2010 by the Genetics Society of America DOI: 10.1534/genetics.109.112284 Fission Yeast Hsk1 (Cdc7) Kinase Is Required After Replication Initiation for Induced Mutagenesis and Proper Response to DNA Alkylation Damage William P. Dolan,*,† Anh-Huy Le,* Henning Schmidt,‡ Ji-Ping Yuan,* Marc Green* and Susan L. Forsburg*,1 *Molecular and Computational Biology Program, University of Southern California, Los Angeles, California 90089, †Division of Biology, University of California, San Diego, California 92093 and ‡Institut fu¨r Genetik, TU Braunschweig, D-38106 Braunschweig, Germany Manuscript received November 20, 2009 Accepted for publication February 16, 2010 ABSTRACT Genome stability in fission yeast requires the conserved S-phase kinase Hsk1 (Cdc7) and its partner Dfp1 (Dbf4). In addition to their established function in the initiation of DNA replication, we show that these proteins are important in maintaining genome integrity later in S phase and G2. hsk1 cells suffer increased rates of mitotic recombination and require recombination proteins for survival. Both hsk1 and dfp1 mutants are acutely sensitive to alkylation damage yet defective in induced mutagenesis. Hsk1 and Dfp1 are associated with the chromatin even after S phase, and normal response to MMS damage corre- lates with the maintenance of intact Dfp1 on chromatin. A screen for MMS-sensitive mutants identified a novel truncation allele, rad35 (dfp1-(1–519)), as well as alleles of other damage-associated genes. Although Hsk1–Dfp1 functions with the Swi1–Swi3 fork protection complex, it also acts independently of the FPC to promote DNA repair. We conclude that Hsk1–Dfp1 kinase functions post-initiation to maintain replica- tion fork stability, an activity potentially mediated by the C terminus of Dfp1.
    [Show full text]
  • Homologous Recombination Rescues Ssdna Gaps Generated by Nucleotide Excision Repair and Reduced Translesion DNA Synthesis In
    Homologous recombination rescues ssDNA gaps PNAS PLUS generated by nucleotide excision repair and reduced translesion DNA synthesis in yeast G2 cells Wenjian Ma, James W. Westmoreland, and Michael A. Resnick1 Chromosome Stability Group, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709 Edited by Philip C. Hanawalt, Stanford University, Stanford, CA, and approved June 21, 2013 (received for review January 26, 2013) Repair of DNA bulky lesions often involves multiple repair path- As we and others have reported, DSBs can be formed as ways such as nucleotide-excision repair, translesion DNA synthesis secondary products during processing of ssDNA lesions arising (TLS), and homologous recombination (HR). Although there is con- from agents such as methyl methanesulfonate (MMS) (8-10) at siderable information about individual pathways, little is known doses that result in closely opposed lesions. Because NER can about the complex interactions or extent to which damage in produce ssDNA gaps of ∼30 nt for a variety of bulky lesions, single strands, such as the damage generated by UV, can result in there is a greater likelihood of secondary generation of DSBs double-strand breaks (DSBs) and/or generate HR. We investigated than with base-excision repair, which generates short resection the consequences of UV-induced lesions in nonreplicating G2 cells regions. However, gap formation and subsequent refilling during of budding yeast. In contrast to WT cells, there was a dramatic NER are tightly coordinated, with repair synthesis starting after increase in ssDNA gaps for cells deficient in the TLS polymerases η incision on the 5′ side of the lesion (which precedes the 3′ in- (Rad30) and ζ (Rev3).
    [Show full text]
  • Methyl-Directed Repair of DNA Base-Pair Mismatches in Vitro
    Proc. Natl. Acad. Sci. USA Vol. 80, pp. 4639-4643, August 1983 Biochemistry Methyl-directed repair of DNA base-pair mismatches in vitro (mutagenesis/gene conversion/DNA methylation) A.-LIEN Lu, SUSANNA CLARK, AND PAUL MODRICH Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710 Communicated by Robert L. Hill, April 18, 1983 ABSTRACT An assay has been developed that permits anal- system requires not only detection of base-pair mismatches but ysis of DNA mismatch repair in cell-free extracts of Escherichia a mechanism for discrimination of parental and newly synthe- coli The method relies on repair of heteroduplex molecules of fl sized strands as well. These authors suggested that the transient R229 DNA, which contain a base-pair mismatch within the single undermethylation of the newly synthesized strand might pro- EcoRI site of the molecule. As observed with mismatch hetero- vide the bias for such discrimination. Indeed, several lines of duplexes of A DNA [Pukila, P. J., Peterson, J., Herman, G., evidence indicate that dam methylation of d(G-A-T-C) se- Modrich, P. & Meselson, M. (1983) Genetics, in press], in vivo mis- quences functions in this respect. Thus, deficiency or over- match correction of fl heteroduplexes is directed by the state of production of this DNA methylase results in a mutator phe- dam methylation of d(G-A-T-C) sequences within the DNA du- notype (13, 14). In addition, genetic analysis has suggested that plex. Thus, the heteroduplex dam methylase participates in a pathway involving mutH, mutL, 5'-G-A-A-T-T-C and mutS function (15, 16).
    [Show full text]
  • CLONING and CHARACTERIZATION of EXCISION Repam GENES
    CLONING AND CHARACTERIZATION OF EXCISION REPAm GENES CLONING AND CHARACTERIZATION OF EXCISION REPAIR GENES KLONERING EN KARAKTERISERING VAN EXCISIE HERSTEL GENEN PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR AAN DE ERASMUS UNIVERSITElT ROTTERDAM OP GEZAG VAN DE RECTOR MAGNIFICUS PROF. DR. P.W.C. AKKERMANS M.A. EN VOLGENS BESLUIT VAN HET COLLEGE VAN DEKANEN. DE OPEN BARE VERDEDIGING ZAL PLAATSVINDEN OP WOENSDAG 27 MAART 1996 OM 13:45 UUR DOOR PETRUS JOHANNES V AN DER SPEK GEBOREN TE DELFr PROMOTIECOMMISSIE Promotoren: Prof. Dr. D. Bootsma Prof. Dr. J.H.J. Hoeijmakers Overige leden: Prof. Dr. LA. Grootegoed Prof. Dr. D. Lindhout Prof. Dr. Ir. A.A. van Zeeland The studies described in this thesis were carried out in the Medical Genetics Centre South-West Netherlands at the department of Cell Biology and Genetics Erasmus University Rotterdam. This project was financially supported by the Medical Genetics Centre and the Dutch Cancer Society. The printing of this thesis was financially supported by: Ames B. V., Autron B. V., Bio­ Rad Laboratories B.V., Biozym B.V., Eurogentec N.V., Het Kasteel van Rhoon, Pharmacia B.V., Schleicher & Schuell Nederland B.V. and Thieme's Echte Thee. Front cover Three dimensional representation of the protein structure of ubiquitin. In blue (identical) and in orange (similar) residues shared by the NER enzyme RAD23 The similar spacefilling model indicates the homologous residues of the conserved core. Molecular modeling and image processing was performed at the National Institutes of Health's division of computer research and technology, Bethesda. USA. Illustrations Mirko Kuit Printing Drukkerij Haveka B.V., Alblasserdam The known is finite, the unknown infinite; intellectually we stand on an island in the midst of an illimitable ocean of inexplicability.
    [Show full text]
  • Barbour-Thesis.Pdf (2.004Mb)
    Synthetically Lethal Interactions Classify Novel Genes in Postreplication Repair in Saccharomyces cerevisiae A thesis submitted to the College of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Microbiology and Immunology University of Saskatchewan Leslie Barbour, B.Sc. © Copyright Leslie Barbour, February 2005. All rights reserved. Permission to Use In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or make other use of material in this thesis in whole or in part should be addressed to: Head of the Department of Microbiology and Immunology Health Sciences Building, 107 Wiggins Road University of Saskatchewan Saskatoon, SK Canada S7N 5E5 i Acknowledgments First I would like to thank my supervisor, Dr.
    [Show full text]
  • DNA Repair Mechanisms and the Bypass of DNA Damage in Saccharomyces Cerevisiae
    YEASTBOOK GENOME ORGANIZATION & INTEGRITY DNA Repair Mechanisms and the Bypass of DNA Damage in Saccharomyces cerevisiae Serge Boiteux* and Sue Jinks-Robertson†,1 *Centre National de la Recherche Scientifique UPR4301 Centre de Biophysique Moléculaire, 45071 Orléans cedex 02, France, and yDepartment of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710 ABSTRACT DNA repair mechanisms are critical for maintaining the integrity of genomic DNA, and their loss is associated with cancer predisposition syndromes. Studies in Saccharomyces cerevisiae have played a central role in elucidating the highly conserved mech- anisms that promote eukaryotic genome stability. This review will focus on repair mechanisms that involve excision of a single strand from duplex DNA with the intact, complementary strand serving as a template to fill the resulting gap. These mechanisms are of two general types: those that remove damage from DNA and those that repair errors made during DNA synthesis. The major DNA-damage repair pathways are base excision repair and nucleotide excision repair, which, in the most simple terms, are distinguished by the extent of single-strand DNA removed together with the lesion. Mistakes made by DNA polymerases are corrected by the mismatch repair pathway, which also corrects mismatches generated when single strands of non-identical duplexes are exchanged during homologous recombination. In addition to the true repair pathways, the postreplication repair pathway allows lesions or structural aberrations that block replicative DNA polymerases to be tolerated. There are two bypass mechanisms: an error-free mechanism that involves a switch to an undamaged template for synthesis past the lesion and an error-prone mechanism that utilizes specialized translesion synthesis DNA polymerases to directly synthesize DNA across the lesion.
    [Show full text]
  • Dihydropyrimidinase Protects from DNA Replication Stress Caused By
    Dihydropyrimidinase protects from DNA replication stress caused by cytotoxic metabolites Jihane Basbous, Antoine Aze, Laurent Chaloin, Rana Lebdy, Dana Hodroj, Cyril Ribeyre, Marion Larroque, Caitlin Shepard, Baek Kim, Alain Pruvost, et al. To cite this version: Jihane Basbous, Antoine Aze, Laurent Chaloin, Rana Lebdy, Dana Hodroj, et al.. Dihydropyrimidi- nase protects from DNA replication stress caused by cytotoxic metabolites. Nucleic Acids Research, Oxford University Press, 2020, 48 (4), pp.1886-1904. 10.1093/nar/gkz1162. hal-02556387 HAL Id: hal-02556387 https://hal.archives-ouvertes.fr/hal-02556387 Submitted on 6 Jul 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution - NonCommercial| 4.0 International License 1886–1904 Nucleic Acids Research, 2020, Vol. 48, No. 4 Published online 19 December 2019 doi: 10.1093/nar/gkz1162 Dihydropyrimidinase protects from DNA replication stress caused by cytotoxic metabolites Jihane Basbous1,*, Antoine Aze1, Laurent Chaloin2, Rana Lebdy1, Dana Hodroj1,3, Cyril
    [Show full text]
  • Mechanisms of Post-Replication DNA Repair
    Review Mechanisms of Post-Replication DNA Repair Yanzhe Gao 1,*, Elizabeth Mutter-Rottmayer 1,2, Anastasia Zlatanou 1, Cyrus Vaziri 1 and Yang Yang 1 1 Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; [email protected] (E.M.-R.); [email protected] (A.Z.); [email protected] (C.V.); [email protected] (Y.Y.) 2 Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599,USA * Correspondence: [email protected] Academic Editor: Eishi Noguchi Received: 5 December 2016; Accepted: 3 February 2017; Published: 8 February 2017 Abstract: Accurate DNA replication is crucial for cell survival and the maintenance of genome stability. Cells have developed mechanisms to cope with the frequent genotoxic injuries that arise from both endogenous and environmental sources. Lesions encountered during DNA replication are often tolerated by post-replication repair mechanisms that prevent replication fork collapse and avert the formation of DNA double strand breaks. There are two predominant post-replication repair pathways, trans-lesion synthesis (TLS) and template switching (TS). TLS is a DNA damage-tolerant and low-fidelity mode of DNA synthesis that utilizes specialized ‘Y-family’ DNA polymerases to replicate damaged templates. TS, however, is an error-free ‘DNA damage avoidance’ mode of DNA synthesis that uses a newly synthesized sister chromatid as a template in lieu of the damaged parent strand. Both TLS and TS pathways are tightly controlled signaling cascades that integrate DNA synthesis with the overall DNA damage response and are thus crucial for genome stability.
    [Show full text]
  • Strategies for DNA Interstrand Crosslink Repair: Insights from Worms, Flies, Frogs, and Slime Molds
    Environmental and Molecular Mutagenesis 51:646^658 (2010) Review Article Strategies for DNA Interstrand Crosslink Repair: Insights From Worms, Flies, Frogs, and Slime Molds Mitch McVey1,2* 1Department of Biology, Tufts University, Medford, Massachusetts 2Program in Genetics, Tufts Sackler School of Graduate Biomedical Sciences, Boston, Massachusetts DNA interstrand crosslinks (ICLs) are complex metazoans, nonmammalian models have become lesions that covalently link both strands of the attractive systems for studying the function(s) of DNA double helix and impede essential cellular key crosslink repair factors. This review discusses processes such as DNA replication and transcrip- the contributions that various model organisms tion. Recent studies suggest that multiple repair have made to the field of ICL repair. Specifically, pathways are involved in their removal. Elegant it highlights how studies performed with C. ele- genetic analysis has demonstrated that at least gans, Drosophila, Xenopus, and the social three distinct sets of pathways cooperate in the amoeba Dictyostelium serve to complement those repair and/or bypass of ICLs in budding yeast. from bacteria, yeast, and mammals. Together, Although the mechanisms of ICL repair in mam- these investigations have revealed that although mals appear similar to those in yeast, important the underlying themes of ICL repair are largely differences have been documented. In addition, conserved, the complement of DNA repair pro- mammalian crosslink repair requires other repair teins utilized and the ways in which each of the factors, such as the Fanconi anemia proteins, proteins is used can vary substantially between whose functions are poorly understood. Because different organisms. Environ. Mol. Mutagen. many of these proteins are conserved in simpler 51:646–658, 2010.
    [Show full text]
  • A Newly Identified Patient with Clinical Xeroderma Pigmentosum Phenotype Has a Non-Sense Mutation in the DDB2 Gene and Incomplet
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector A Newly Identified Patient with Clinical Xeroderma Pigmentosum Phenotype has a Non-Sense Mutation in the DDB2 Gene and Incomplete Repair in (6-4) Photoproducts Toshiki Itoh, Toshio Mori,† Hiroaki Ohkubo,* and Masaru Yamaizumi Department of Cell Genetics, *Gene Regulation, Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Kumamoto, Japan; and †Radioisotope Center, Nara Medical University, Nara, Japan We report here a patient (Ops1) with clinical photosen- pattern repair in cis-syn cyclobutane sitivity, including pigmented or depigmented macules pyrimidine dimers by repair kinetics using the enzyme- and patches, and multiple skin neoplasias (malignant linked immunosorbent assay. Moreover, Ops1 cells melanomas, basal cell carcinomas, and squamous cell were defective in a damage-specific DNA binding carcinomas in situ) in sun-exposed areas. These clinical protein and carried a non-sense mutation in the DDB2 features are reminiscent of xeroderma pigmentosum. gene. These results suggest that (i) the DDB2 gene is As cells from Ops1 showed normal levels in DNA somewhat related to skin carcinogenesis, photoaging repair synthesis in vivo (unscheduled DNA synthesis and skin, and the removal of (6-4) photoproducts; (ii) although it is believed that cyclobutane pyrimidine recovery of RNA synthesis after ultraviolet irradiation), dimers are the principal mutagenic lesion and (6-4) we performed a postreplication repair assay and recov- photoproducts are less likely to contribute to ultravi- ery of replicative DNA synthesis after ultraviolet irradi- olet-induced mutations in mammals, Ops1 is one of ation to investigate if Ops1 cells belonged to a the ultraviolet-induced mutagenic models induced by xeroderma pigmentosum variant pattern.
    [Show full text]
  • Supplementary Material Table 1 Gene Encoded Protein Function TSC2 Tuberin; in Complex with TSC1, This Tumor Suppressor Inhibits
    BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Case Rep Supplementary Material Table 1 Gene Encoded protein function TSC2 Tuberin; In complex with TSC1, this tumor suppressor inhibits the nutrient-mediated or growth factor-stimulated phosphorylation of S6K1 and EIF4EBP1 by negatively regulating mTORC1 signaling. Acts as a GTPase-activating protein (GAP) for the small GTPase RHEB, a direct activator of the protein kinase activity of mTORC1. May also play a role in microtubule-mediated protein transport. Also stimulates the intrinsic GTPase activity of the Ras-related proteins RAP1A and RAB5; Armadillo-like helical domain containing PHOX2B Paired mesoderm homeobox protein 2B; Involved in the development of several major noradrenergic neuron populations, including the locus coeruleus. Transcription factor which could determine a neurotransmitter phenotype in vertebrates. Enhances second- messenger-mediated activation of the dopamine beta-hydrolase and c-fos promoters, and of several enhancers including cAMP-response element and serum- response element; Belongs to the paired homeobox family FANCE Fanconi anemia group E protein; As part of the Fanconi anemia (FA) complex functions in DNA cross-links repair. Required for the nuclear accumulation of FANCC and provides a critical bridge between the FA complex and FANCD2 ISL1 Insulin gene enhancer protein ISL-1; DNA-binding transcriptional activator. Recognizes and binds to the consensus octamer binding site 5'-ATAATTAA-3' in promoter of target genes. Plays a fundamental role in the gene regulatory network essential for retinal ganglion cell (RGC) differentiation.
    [Show full text]