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Smith SS. The bisulfite reaction with cytosine and genomic DNA structure. Anal Biochem 2024; 691:115532. [PMID: 38609028 DOI: 10.1016/j.ab.2024.115532] [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: 12/09/2023] [Revised: 02/19/2024] [Accepted: 04/04/2024] [Indexed: 04/14/2024]
Abstract
The bisulfite reaction with native DNA has been extensively employed in the detection of non-B DNA structures that can form spontaneously in DNA. These sequences are dynamic in that they can adopt both normal Watson-Crick paired B-DNA or unusual structures like the Triplex, G-Quadruplex, i-motif and Cruciform or Hairpin. Considerable evidence now suggests that these dynamic sequences play roles in both epigenetics and mutagenesis. The bisulfite reaction with native DNA offers a key approach to their detection. In this application whole cells, isolated nuclei or isolated DNA are treated with bisulfite under non-denaturing conditions in order to detect bisulfite accessible regions DNA that are associated with these structures. Here I review the stereochemistry of the bisulfite reaction, the electronic structure of its DNA cytosine substrates and its application in the detection of unusual structures in native DNA.
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Affiliation(s)
- Steven S Smith
- Department of Stem Cell Biology and Regenerative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA, USA.
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Dalin S, Webster S, Sugawara N, Zhang S, Wu Q, Cui T, Liang V, Beroukhim R, Haber JE. Double-strand break repair-associated intragenic deletions and tandem duplications suggest the architecture of the repair replication fork. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561461. [PMID: 37873277 PMCID: PMC10592705 DOI: 10.1101/2023.10.09.561461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Double-strand break (DSB) repair is associated with a 1000-fold increase in mutations compared to normal replication of the same sequences. In budding yeast, repair of an HO endonuclease-induced DSB at the MATα locus can be repaired by using a homologous, heterochromatic HMR::Kl-URA3 donor harboring a transcriptionally silenced URA3 gene, resulting in a MAT::URA3 (Ura+) repair product where URA3 is expressed. Repair-associated ura3- mutations can be selected by resistance to 5-fluoroorotic acid (FOA). Using this system, we find that a major class of mutations are -1 deletions, almost always in homonucleotide runs, but there are few +1 insertions. In contrast, +1 and -1 insertions in homonucleotide runs are nearly equal among spontaneous mutations. Approximately 10% of repair-associated mutations are interchromosomal template switches (ICTS), even though the K. lactis URA3 sequence embedded in HMR is only 72% identical with S. cerevisiae ura3-52 sequences on a different chromosome. ICTS events begin and end in regions of short microhomology, averaging 7 bp. Long microhomologies are favored, but some ICTS junctions are as short as 2 bp. Both repair-associated intragenic deletions (IDs) and tandem duplications (TDs) are recovered, with junctions sharing short stretches of, on average, 6 bp of microhomology. Intragenic deletions are more than 5 times more frequent than TDs. IDs have a mean length of 60 bp, but, surprisingly there are almost no deletions shorter than 25 bp. In contrast, TDs average only 12 bp. The usage of microhomologies among intragenic deletions is not strongly influenced by the degree of adjacent homeology. Together, these data provide a picture of the structure of the repair replication fork. We suggest that IDs and TDs occur within the migrating D-loop in which DNA polymerase δ copies the template, where the 3' end of a partly copied new DNA strand can dissociate and anneal with a single-stranded region of microhomology that lies either in front or behind the 3' end, within the open structure of a migrating D-loop. Our data suggest that ~100 bp ahead of the polymerase is "open," but that part of the repair replication apparatus remains bound in the 25 bp ahead of the newly copied DNA, preventing annealing. In contrast, the template region behind the polymerase appears to be rapidly reannealed, limiting template switching to a very short region.
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Affiliation(s)
- Simona Dalin
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Departments of Cancer Biology and Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Sophie Webster
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Departments of Cancer Biology and Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Neal Sugawara
- Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
| | - Shu Zhang
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Departments of Cancer Biology and Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Qiuqin Wu
- Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
| | - Tracy Cui
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Departments of Cancer Biology and Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
- Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
| | - Victoria Liang
- Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
| | - Rameen Beroukhim
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Departments of Cancer Biology and Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - James E. Haber
- Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02454-9110
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Reitz D, Savocco J, Piazza A, Heyer WD. Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae. J Vis Exp 2022:10.3791/64240. [PMID: 36155960 PMCID: PMC10205173 DOI: 10.3791/64240] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
DNA damage, including DNA double-stranded breaks and inter-strand cross-links, incurred during the S and G2 phases of the cell cycle can be repaired by homologous recombination (HR). In addition, HR represents an important mechanism of replication fork rescue following stalling or collapse. The regulation of the many reversible and irreversible steps of this complex pathway promotes its fidelity. The physical analysis of the recombination intermediates formed during HR enables the characterization of these controls by various nucleoprotein factors and their interactors. Though there are well-established methods to assay specific events and intermediates in the recombination pathway, the detection of D-loop formation and extension, two critical steps in this pathway, has proved challenging until recently. Here, efficient methods for detecting key events in the HR pathway, namely DNA double-stranded break formation, D-loop formation, D-loop extension, and the formation of products via break-induced replication (BIR) in Saccharomyces cerevisiae are described. These assays detect their relevant recombination intermediates and products with high sensitivity and are independent of cellular viability. The detection of D-loops, D-loop extension, and the BIR product is based on proximity ligation. Together, these assays allow for the study of the kinetics of HR at the population level to finely address the functions of HR proteins and regulators at significant steps in the pathway.
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Affiliation(s)
- Diedre Reitz
- Department of Microbiology & Molecular Genetics, University of California, Davis
| | - Jérôme Savocco
- Laboratory of Biology & Modeling of the Cell, École Normale Supérieure de Lyon
| | - Aurèle Piazza
- Laboratory of Biology & Modeling of the Cell, École Normale Supérieure de Lyon;
| | - Wolf-Dietrich Heyer
- Department of Microbiology & Molecular Genetics, University of California, Davis; Department of Molecular & Cellular Biology, University of California, Davis;
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Shah SS, Hartono S, Piazza A, Som V, Wright W, Chédin F, Heyer WD. Rdh54/Tid1 inhibits Rad51-Rad54-mediated D-loop formation and limits D-loop length. eLife 2020; 9:59112. [PMID: 33185188 PMCID: PMC7695457 DOI: 10.7554/elife.59112] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 11/12/2020] [Indexed: 02/06/2023] Open
Abstract
Displacement loops (D-loops) are critical intermediates formed during homologous recombination. Rdh54 (a.k.a. Tid1), a Rad54 paralog in Saccharomyces cerevisiae, is well-known for its role with Dmc1 recombinase during meiotic recombination. Yet contrary to Dmc1, Rdh54/Tid1 is also present in somatic cells where its function is less understood. While Rdh54/Tid1 enhances the Rad51 DNA strand invasion activity in vitro, it is unclear how it interplays with Rad54. Here, we show that Rdh54/Tid1 inhibits D-loop formation by Rad51 and Rad54 in an ATPase-independent manner. Using a novel D-loop Mapping Assay, we further demonstrate that Rdh54/Tid1 uniquely restricts the length of Rad51-Rad54-mediated D-loops. The alterations in D-loop properties appear to be important for cell survival and mating-type switch in haploid yeast. We propose that Rdh54/Tid1 and Rad54 compete for potential binding sites within the Rad51 filament, where Rdh54/Tid1 acts as a physical roadblock to Rad54 translocation, limiting D-loop formation and D-loop length.
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Affiliation(s)
- Shanaya Shital Shah
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States
| | - Stella Hartono
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Aurèle Piazza
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States.,CR CNRS UMR5239, Team Genome Mechanics, Laboratory of Biology and Modelling of the Cell, Ecole Normale Supérieure de Lyon 46, Lyon, France
| | - Vanessa Som
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States
| | - William Wright
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States.,Mammoth Biosciences, South San Francisco, United States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States.,Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
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