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Handelmann CR, Tsompana M, Samudrala R, Buck M. The impact of nucleosome structure on CRISPR/Cas9 fidelity. Nucleic Acids Res 2023; 51:2333-2344. [PMID: 36727449 PMCID: PMC10018339 DOI: 10.1093/nar/gkad021] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 01/05/2023] [Accepted: 01/31/2023] [Indexed: 02/03/2023] Open
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR) Cas system is a powerful tool that has the potential to become a therapeutic gene editor in the near future. Cas9 is the best studied CRISPR system and has been shown to have problems that restrict its use in therapeutic applications. Chromatin structure is a known impactor of Cas9 targeting and there is a gap in knowledge on Cas9's efficacy when targeting such locations. To quantify at a single base pair resolution how chromatin inhibits on-target gene editing relative to off-target editing of exposed mismatching targets, we developed the gene editor mismatch nucleosome inhibition assay (GEMiNI-seq). GEMiNI-seq utilizes a library of nucleosome sequences to examine all target locations throughout nucleosomes in a single assay. The results from GEMiNI-seq revealed that the location of the protospacer-adjacent motif (PAM) sequence on the nucleosome edge drives the ability for Cas9 to access its target sequence. In addition, Cas9 had a higher affinity for exposed mismatched targets than on-target sequences within a nucleosome. Overall, our results show how chromatin structure impacts the fidelity of Cas9 to potential targets and highlight how targeting sequences with exposed PAMs could limit off-target gene editing, with such considerations improving Cas9 efficacy and resolving current limitations.
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Affiliation(s)
- Christopher R Handelmann
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Biomedical Informatics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Maria Tsompana
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Ram Samudrala
- Department of Biomedical Informatics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
| | - Michael J Buck
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Department of Biomedical Informatics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
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Harpprecht L, Baldi S, Schauer T, Schmidt A, Bange T, Robles MS, Kremmer E, Imhof A, Becker PB. A Drosophila cell-free system that senses DNA breaks and triggers phosphorylation signalling. Nucleic Acids Res 2019; 47:7444-7459. [PMID: 31147711 PMCID: PMC6698661 DOI: 10.1093/nar/gkz473] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 11/23/2022] Open
Abstract
Preblastoderm Drosophila embryo development is characterized by fast cycles of nuclear divisions. Extracts from these embryos can be used to reconstitute complex chromatin with high efficiency. We now discovered that this chromatin assembly system contains activities that recognize unprotected DNA ends and signal DNA damage through phosphorylation. DNA ends are initially bound by Ku and MRN complexes. Within minutes, the phosphorylation of H2A.V (homologous to γH2A.X) initiates from DNA breaks and spreads over tens of thousands DNA base pairs. The γH2A.V phosphorylation remains tightly associated with the damaged DNA and does not spread to undamaged DNA in the same reaction. This first observation of long-range γH2A.X spreading along damaged chromatin in an in vitro system provides a unique opportunity for mechanistic dissection. Upon further incubation, DNA ends are rendered single-stranded and bound by the RPA complex. Phosphoproteome analyses reveal damage-dependent phosphorylation of numerous DNA-end-associated proteins including Ku70, RPA2, CHRAC16, the exonuclease Rrp1 and the telomer capping complex. Phosphorylation of spindle assembly checkpoint components and of microtubule-associated proteins required for centrosome integrity suggests this cell-free system recapitulates processes involved in the regulated elimination of fatally damaged syncytial nuclei.
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Affiliation(s)
- Lisa Harpprecht
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Sandro Baldi
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science Munich, LMU Munich, 81377 Munich, Germany
| | - Tamas Schauer
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
- Bioinformatics Unit, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Andreas Schmidt
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
- Protein Analysis Unit, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Tanja Bange
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany
| | - Maria S Robles
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, German Research Center for Environmental Health, 81377 Munich, Germany
| | - Axel Imhof
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science Munich, LMU Munich, 81377 Munich, Germany
- Protein Analysis Unit, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
| | - Peter B Becker
- Molecular Biology Division, Biomedical Center, LMU Munich, 82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science Munich, LMU Munich, 81377 Munich, Germany
- To whom correspondence should be addressed. Tel: +49 89 2180 75427; Fax: +49 89 2180 75425;
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Meas R, Wyrick JJ, Smerdon MJ. Nucleosomes Regulate Base Excision Repair in Chromatin. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2019; 780:29-36. [PMID: 31388331 PMCID: PMC6684245 DOI: 10.1016/j.mrrev.2017.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chromatin is a significant barrier to many DNA damage response (DDR) factors, such as DNA repair enzymes, that process DNA lesions to reduce mutations and prevent cell death; yet, paradoxically, chromatin also has a critical role in many signaling pathways that regulate the DDR. The primary level of DNA packaging in chromatin is the nucleosome core particle (NCP), consisting of DNA wrapped around an octamer of the core histones H2A, H2B, H3 and H4. Here, we review recent studies characterizing how the packaging of DNA into nucleosomes modulates the activity of the base excision repair (BER) pathway and dictates BER subpathway choice. We also review new evidence indicating that the histone amino-terminal tails coordinately regulate multiple DDR pathways during the repair of alkylation damage in the budding yeast Saccharomyces cerevisiae.
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Affiliation(s)
- Rithy Meas
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520
| | - John J. Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520
| | - Michael J. Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520
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Hodges AJ, Plummer DA, Wyrick JJ. NuA4 acetyltransferase is required for efficient nucleotide excision repair in yeast. DNA Repair (Amst) 2018; 73:91-98. [PMID: 30473425 DOI: 10.1016/j.dnarep.2018.11.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/02/2018] [Accepted: 11/12/2018] [Indexed: 12/13/2022]
Abstract
The nucleotide excision repair (NER) pathway is critical for removing damage induced by ultraviolet (UV) light and other helix-distorting lesions from cellular DNA. While efficient NER is critical to avoid cell death and mutagenesis, NER activity is inhibited in chromatin due to the association of lesion-containing DNA with histone proteins. Histone acetylation has emerged as an important mechanism for facilitating NER in chromatin, particularly acetylation catalyzed by the Spt-Ada-Gcn5 acetyltransferase (SAGA); however, it is not known if other histone acetyltransferases (HATs) promote NER activity in chromatin. Here, we report that the essential Nucleosome Acetyltransferase of histone H4 (NuA4) complex is required for efficient NER in Saccharomyces cerevisiae. Deletion of the non-essential Yng2 subunit of the NuA4 complex causes a general defect in repair of UV-induced cyclobutane pyrimidine dimers (CPDs) in yeast; in contrast, deletion of the Sas3 catalytic subunit of the NuA3 complex does not affect repair. Rapid depletion of the essential NuA4 catalytic subunit Esa1 using the anchor-away method also causes a defect in NER, particularly at the heterochromatic HML locus. We show that disrupting the Sds3 subunit of the Rpd3L histone deacetylase (HDAC) complex rescued the repair defect associated with loss of Esa1 activity, suggesting that NuA4-catalyzed acetylation is important for efficient NER in heterochromatin.
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Affiliation(s)
- Amelia J Hodges
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, United States
| | - Dalton A Plummer
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, United States
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, United States; Center for Reproductive Biology, Washington State University, Pullman, WA, 99164, United States.
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Yang Y, Hu J, Selby CP, Li W, Yimit A, Jiang Y, Sancar A. Single-nucleotide resolution analysis of nucleotide excision repair of ribosomal DNA in humans and mice. J Biol Chem 2018; 294:210-217. [PMID: 30413533 DOI: 10.1074/jbc.ra118.006121] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Indexed: 12/15/2022] Open
Abstract
The unique nucleolar environment, the repetitive nature of ribosomal DNA (rDNA), and especially the possible involvement of RNA polymerase I (RNAPI) in transcription-coupled repair (TCR) have made the study of repair of rDNA both interesting and challenging. TCR, the transcription-dependent, preferential excision repair of the template strand compared with the nontranscribed (coding) strand has been clearly demonstrated in genes transcribed by RNAPII. Whether TCR occurs in rDNA is unresolved. In the present work, we have applied analytical methods to map repair events in rDNA using data generated by the newly developed XR-seq procedure, which measures excision repair genome-wide with single-nucleotide resolution. We find that in human and mouse cell lines, rDNA is not subject to TCR of damage caused by UV or by cisplatin.
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Affiliation(s)
- Yanyan Yang
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Jinchuan Hu
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599; Fifth People's Hospital of Shanghai and Institute of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Christopher P Selby
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Wentao Li
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Askar Yimit
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Yuchao Jiang
- Departments of Biostatistics and Genetics, University of North Carolina, Chapel Hill, North Carolina 27599; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599.
| | - Aziz Sancar
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599.
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Zurita M, Cruz-Becerra G. TFIIH: New Discoveries Regarding its Mechanisms and Impact on Cancer Treatment. J Cancer 2016; 7:2258-2265. [PMID: 27994662 PMCID: PMC5166535 DOI: 10.7150/jca.16966] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 09/30/2016] [Indexed: 12/16/2022] Open
Abstract
The deregulation of gene expression is a characteristic of cancer cells, and malignant cells require very high levels of transcription to maintain their cancerous phenotype and survive. Therefore, components of the basal transcription machinery may be considered as targets to preferentially kill cancerous cells. TFIIH is a multisubunit basal transcription factor that also functions in nucleotide excision repair. The recent discoveries of some small molecules that interfere with TFIIH and that preferentially kill cancer cells have increased researchers' interest to elucidate the complex mechanisms by which TFIIH operates. In this review, we summarize the knowledge generated during the 25 years of TFIIH research, highlighting the recent advances in TFIIH structural and mechanistic analyses that suggest the potential of TFIIH as a target for cancer treatment.
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Affiliation(s)
- Mario Zurita
- Departamento de Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México. Av. Universidad 2001, Cuernavaca, Morelos 62250, México
| | - Grisel Cruz-Becerra
- Departamento de Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México. Av. Universidad 2001, Cuernavaca, Morelos 62250, México
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Mao P, Wyrick JJ, Roberts SA, Smerdon MJ. UV-Induced DNA Damage and Mutagenesis in Chromatin. Photochem Photobiol 2016; 93:216-228. [PMID: 27716995 DOI: 10.1111/php.12646] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/14/2016] [Indexed: 12/19/2022]
Abstract
UV radiation induces photolesions that distort the DNA double helix and, if not repaired, can cause severe biological consequences, including mutagenesis or cell death. In eukaryotes, both the formation and repair of UV damage occur in the context of chromatin, in which genomic DNA is packaged with histones into nucleosomes and higher order chromatin structures. Here, we review how chromatin impacts the formation of UV photoproducts in eukaryotic cells. We describe the initial discovery that nucleosomes and other DNA binding proteins induce characteristic "photofootprints" during the formation of UV photoproducts. We also describe recent progress in genomewide methods for mapping UV damage, which echoes early biochemical studies, and highlights the role of nucleosomes and transcription factors in UV damage formation and repair at unprecedented resolution. Finally, we discuss our current understanding of how the distribution and repair of UV-induced DNA damage influence mutagenesis in human skin cancers.
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Affiliation(s)
- Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA
| | - John J Wyrick
- School of Molecular Biosciences, Washington State University, Pullman, WA.,Center for Reproductive Biology, Washington State University, Pullman, WA
| | - Steven A Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA
| | - Michael J Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, WA
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