1
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Sugawara N, Towne MJ, Lovett ST, Haber JE. Spontaneous and double-strand break repair-associated quasipalindrome and frameshift mutagenesis in budding yeast: role of mismatch repair. Genetics 2024; 227:iyae068. [PMID: 38691577 DOI: 10.1093/genetics/iyae068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 08/09/2023] [Accepted: 03/06/2024] [Indexed: 05/03/2024] Open
Abstract
Although gene conversion (GC) in Saccharomyces cerevisiae is the most error-free way to repair double-strand breaks (DSBs), the mutation rate during homologous recombination is 1,000 times greater than during replication. Many mutations involve dissociating a partially copied strand from its repair template and re-aligning with the same or another template, leading to -1 frameshifts in homonucleotide runs, quasipalindrome (QP)-associated mutations and microhomology-mediated interchromosomal template switches. We studied GC induced by HO endonuclease cleavage at MATα, repaired by an HMR::KI-URA3 donor. We inserted into HMR::KI-URA3 an 18-bp inverted repeat where one arm had a 4-bp insertion. Most GCs yield MAT::KI-ura3::QP + 4 (Ura-) outcomes, but template-switching produces Ura+ colonies, losing the 4-bp insertion. If the QP arm without the insertion is first encountered by repair DNA polymerase and is then (mis)used as a template, the palindrome is perfected. When the QP + 4 arm is encountered first, Ura+ derivatives only occur after second-end capture and second-strand synthesis. QP + 4 mutations are suppressed by mismatch repair (MMR) proteins Msh2, Msh3, and Mlh1, but not Msh6. Deleting Rdh54 significantly reduces QP mutations only when events creating Ura+ occur in the context of a D-loop but not during second-strand synthesis. A similar bias is found with a proofreading-defective DNA polymerase mutation (poI3-01). DSB-induced mutations differed in several genetic requirements from spontaneous events. We also created a + 1 frameshift in the donor, expanding a run of 4 Cs to 5 Cs. Again, Ura+ recombinants markedly increased by disabling MMR, suggesting that MMR acts during GC but favors the unbroken, template strand.
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Affiliation(s)
- Neal Sugawara
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110, USA
| | - Mason J Towne
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110, USA
| | - Susan T Lovett
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110, USA
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center MS029, Brandeis University, Waltham, MA 02454-9110, USA
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2
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Musmaker K, Wells J, Tsai MC, Comeron JM, Malkova A. Alternative Lengthening of Telomeres in Yeast: Old Questions and New Approaches. Biomolecules 2024; 14:113. [PMID: 38254712 PMCID: PMC10813009 DOI: 10.3390/biom14010113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Alternative lengthening of telomeres (ALT) is a homologous recombination-based pathway utilized by 10-15% of cancer cells that allows cells to maintain their telomeres in the absence of telomerase. This pathway was originally discovered in the yeast Saccharomyces cerevisiae and, for decades, yeast has served as a robust model to study ALT. Using yeast as a model, two types of ALT (RAD51-dependent and RAD51-independent) have been described. Studies in yeast have provided the phenotypic characterization of ALT survivors, descriptions of the proteins involved, and implicated break-induced replication (BIR) as the mechanism responsible for ALT. Nevertheless, many questions have remained, and answering them has required the development of new quantitative methods. In this review we discuss the historic aspects of the ALT investigation in yeast as well as new approaches to investigating ALT, including ultra-long sequencing, computational modeling, and the use of population genetics. We discuss how employing new methods contributes to our current understanding of the ALT mechanism and how they may expand our understanding of ALT in the future.
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Affiliation(s)
- Kendra Musmaker
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Jacob Wells
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Meng-Chia Tsai
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Josep M. Comeron
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
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3
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Brewer BJ, Dunham MJ, Raghuraman MK. A unifying model that explains the origins of human inverted copy number variants. PLoS Genet 2024; 20:e1011091. [PMID: 38175827 PMCID: PMC10766186 DOI: 10.1371/journal.pgen.1011091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
With the release of the telomere-to-telomere human genome sequence and the availability of both long-read sequencing and optical genome mapping techniques, the identification of copy number variants (CNVs) and other structural variants is providing new insights into human genetic disease. Different mechanisms have been proposed to account for the novel junctions in these complex architectures, including aberrant forms of DNA replication, non-allelic homologous recombination, and various pathways that repair DNA breaks. Here, we have focused on a set of structural variants that include an inverted segment and propose that they share a common initiating event: an inverted triplication with long, unstable palindromic junctions. The secondary rearrangement of these palindromes gives rise to the various forms of inverted structural variants. We postulate that this same mechanism (ODIRA: origin-dependent inverted-repeat amplification) that creates the inverted CNVs in inherited syndromes also generates the palindromes found in cancers.
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Affiliation(s)
- Bonita J. Brewer
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Maitreya J. Dunham
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - M. K. Raghuraman
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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4
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Hu J, Ferlez B, Dau J, Crickard JB. Rad53 regulates the lifetime of Rdh54 at homologous recombination intermediates. Nucleic Acids Res 2023; 51:11688-11705. [PMID: 37850655 PMCID: PMC10681728 DOI: 10.1093/nar/gkad848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/12/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023] Open
Abstract
Rdh54 is a conserved DNA translocase that participates in homologous recombination (HR), DNA checkpoint adaptation, and chromosome segregation. Saccharomyces cerevisiae Rdh54 is a known target of the Mec1/Rad53 signaling axis, which globally protects genome integrity during DNA metabolism. While phosphorylation of DNA repair proteins by Mec1/Rad53 is critical for HR progression little is known about how specific post translational modifications alter HR reactions. Phosphorylation of Rdh54 is linked to protection of genomic integrity but the consequences of modification remain poorly understood. Here, we demonstrate that phosphorylation of the Rdh54 C-terminus by the effector kinase Rad53 regulates Rdh54 clustering activity as revealed by single molecule imaging. This stems from phosphorylation dependent and independent interactions between Rdh54 and Rad53. Genetic assays reveal that loss of phosphorylation leads to phenotypic changes resulting in loss-of-heterozygosity (LOH) outcomes. Our data highlight Rad53 as a key regulator of HR intermediates through activation and attenuation of Rdh54 motor function.
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Affiliation(s)
- Jingyi Hu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Bryan Ferlez
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Jennifer Dau
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - J Brooks Crickard
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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5
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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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6
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Polleys EJ, Del Priore I, Haber JE, Freudenreich CH. Structure-forming CAG/CTG repeats interfere with gap repair to cause repeat expansions and chromosome breaks. Nat Commun 2023; 14:2469. [PMID: 37120647 PMCID: PMC10148874 DOI: 10.1038/s41467-023-37901-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 04/04/2023] [Indexed: 05/01/2023] Open
Abstract
Expanded CAG/CTG repeats are sites of DNA damage, leading to repeat length changes. Homologous recombination (HR) is one cause of repeat instability and we hypothesized that gap filling was a driver of repeat instability during HR. To test this, we developed an assay such that resection and ssDNA gap fill-in would occur across a (CAG)70 or (CTG)70 repeat tract. When the ssDNA template was a CTG sequence, there were increased repeat contractions and a fragile site was created leading to large-scale deletions. When the CTG sequence was on the resected strand, resection was inhibited, resulting in repeat expansions. Increased nucleolytic processing by deletion of Rad9, the ortholog of 53BP1, rescued repeat instability and chromosome breakage. Loss of Rad51 increased contractions implicating a protective role for Rad51 on ssDNA. Together, our work implicates structure-forming repeats as an impediment to resection and gap-filling which can lead to mutations and large-scale deletions.
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Affiliation(s)
- Erica J Polleys
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
| | | | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, 02454, USA
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7
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Keymakh M, Dau J, Hu J, Ferlez B, Lisby M, Crickard JB. Rdh54 stabilizes Rad51 at displacement loop intermediates to regulate genetic exchange between chromosomes. PLoS Genet 2022; 18:e1010412. [PMID: 36099310 PMCID: PMC9506641 DOI: 10.1371/journal.pgen.1010412] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/23/2022] [Accepted: 09/04/2022] [Indexed: 11/20/2022] Open
Abstract
Homologous recombination (HR) is a double-strand break DNA repair pathway that preserves chromosome structure. To repair damaged DNA, HR uses an intact donor DNA sequence located elsewhere in the genome. After the double-strand break is repaired, DNA sequence information can be transferred between donor and recipient DNA molecules through different mechanisms, including DNA crossovers that form between homologous chromosomes. Regulation of DNA sequence transfer is an important step in effectively completing HR and maintaining genome integrity. For example, mitotic exchange of information between homologous chromosomes can result in loss-of-heterozygosity (LOH), and in higher eukaryotes, the development of cancer. The DNA motor protein Rdh54 is a highly conserved DNA translocase that functions during HR. Several existing phenotypes in rdh54Δ strains suggest that Rdh54 may regulate effective exchange of DNA during HR. In our current study, we used a combination of biochemical and genetic techniques to dissect the role of Rdh54 on the exchange of genetic information during DNA repair. Our data indicate that RDH54 regulates DNA strand exchange by stabilizing Rad51 at an early HR intermediate called the displacement loop (D-loop). Rdh54 acts in opposition to Rad51 removal by the DNA motor protein Rad54. Furthermore, we find that expression of a catalytically inactivate allele of Rdh54, rdh54K318R, favors non-crossover outcomes. From these results, we propose a model for how Rdh54 may kinetically regulate strand exchange during homologous recombination. Homologous recombination is an important pathway in repairing DNA double strand breaks. For the purposes of this study, HR can be divided into two stages. The first is a DNA repair stage in which the broken DNA molecule is fixed. In the second stage, information can move from one DNA molecule to another. Enzymes that use the power of ATP hydrolysis to move along dsDNA aid in regulating both stages of HR. In this work we focused on the understudied DNA motor protein Rdh54. We combined genetic and biochemical approaches to show that Rdh54 regulates HR by stabilizing the recombinase protein Rad51 at early HR intermediates.
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Affiliation(s)
- Margaret Keymakh
- Deparment of Molecular Biology and Genetics, Cornell University Ithaca, Ithaca, New York, United States of America
| | - Jennifer Dau
- Deparment of Molecular Biology and Genetics, Cornell University Ithaca, Ithaca, New York, United States of America
| | - Jingyi Hu
- Deparment of Molecular Biology and Genetics, Cornell University Ithaca, Ithaca, New York, United States of America
| | - Bryan Ferlez
- Deparment of Molecular Biology and Genetics, Cornell University Ithaca, Ithaca, New York, United States of America
| | - Michael Lisby
- Department of Biology, University of Copenhagen, Copenhagen N, Denmark
| | - J. Brooks Crickard
- Deparment of Molecular Biology and Genetics, Cornell University Ithaca, Ithaca, New York, United States of America
- * E-mail:
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8
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Wu X, Malkova A. Break-induced replication mechanisms in yeast and mammals. Curr Opin Genet Dev 2021; 71:163-170. [PMID: 34481360 DOI: 10.1016/j.gde.2021.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/17/2021] [Accepted: 08/05/2021] [Indexed: 11/26/2022]
Abstract
Break-induced replication (BIR) is a pathway specialized in repair of double-strand DNA breaks with only one end capable of invading homologous template that can arise following replication collapse, telomere erosion or DNA cutting by site-specific endonucleases. For a long time, yeast remained the only model system to study BIR. Studies in yeast demonstrated that BIR represents an unusual mode of DNA synthesis that is driven by a migrating bubble and leads to conservative inheritance of newly synthesized DNA. This unusual type of DNA synthesis leads to high levels of mutations and chromosome rearrangements. Recently, multiple examples of BIR were uncovered in mammalian cells that allowed the comparison of BIR between organisms. It appeared initially that BIR in mammalian cells is predominantly independent of RAD51, and therefore different from BIR that is predominantly Rad51-dependent in yeast. However, a series of systematic studies utilizing site-specific DNA breaks for BIR initiation in mammalian reporters led to the discovery of highly efficient RAD51-dependent BIR, allowing side-by side comparison with BIR in yeast which is the focus of this review.
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Affiliation(s)
- Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States.
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, United States.
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9
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Crickard JB. Discrete roles for Rad54 and Rdh54 during homologous recombination. Curr Opin Genet Dev 2021; 71:48-54. [PMID: 34293661 DOI: 10.1016/j.gde.2021.06.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/25/2021] [Accepted: 06/29/2021] [Indexed: 11/17/2022]
Abstract
Rad54 and Rdh54 are Snf2 DNA motor proteins that function during maintenance of genomic integrity. Though highly related, Rad54 and Rdh54 have different biochemical and genetic functions during maintenance of genomic integrity. Rad54 functions primarily during the homology search and strand invasion steps of homologous recombination, while Rdh54 appears to play a minor role in these processes. More recently it has been shown that Rdh54 functions as a pathway branch point at HR intermediates, and as has a role in cell cycle recovery. Here we will explore recent advances that have improved our understanding of the role these two DNA motor proteins play during DNA repair.
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Affiliation(s)
- John Brooks Crickard
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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10
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Learning Yeast Genetics from Miro Radman. Cells 2021; 10:cells10040945. [PMID: 33923882 PMCID: PMC8072546 DOI: 10.3390/cells10040945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 11/17/2022] Open
Abstract
Miroslav Radman's far-sighted ideas have penetrated many aspects of our study of the repair of broken eukaryotic chromosomes. For over 35 years my lab has studied different aspects of the repair of chromosomal breaks in the budding yeast, Saccharomyces cerevisiae. From the start, we have made what we thought were novel observations that turned out to have been predicted by Miro's extraordinary work in the bacterium Escherichia coli and then later in the radiation-resistant Dienococcus radiodurans. In some cases, we have been able to extend some of his ideas a bit further.
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11
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Frequent loss of heterozygosity in CRISPR-Cas9-edited early human embryos. Proc Natl Acad Sci U S A 2021; 118:2004832117. [PMID: 34050011 DOI: 10.1073/pnas.2004832117] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
CRISPR-Cas9 genome editing is a promising technique for clinical applications, such as the correction of disease-associated alleles in somatic cells. The use of this approach has also been discussed in the context of heritable editing of the human germ line. However, studies assessing gene correction in early human embryos report low efficiency of mutation repair, high rates of mosaicism, and the possibility of unintended editing outcomes that may have pathologic consequences. We developed computational pipelines to assess single-cell genomics and transcriptomics datasets from OCT4 (POU5F1) CRISPR-Cas9-targeted and control human preimplantation embryos. This allowed us to evaluate on-target mutations that would be missed by more conventional genotyping techniques. We observed loss of heterozygosity in edited cells that spanned regions beyond the POU5F1 on-target locus, as well as segmental loss and gain of chromosome 6, on which the POU5F1 gene is located. Unintended genome editing outcomes were present in ∼16% of the human embryo cells analyzed and spanned 4-20 kb. Our observations are consistent with recent findings indicating complexity at on-target sites following CRISPR-Cas9 genome editing. Our work underscores the importance of further basic research to assess the safety of genome editing techniques in human embryos, which will inform debates about the potential clinical use of this technology.
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12
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Kockler ZW, Comeron JM, Malkova A. A unified alternative telomere-lengthening pathway in yeast survivor cells. Mol Cell 2021; 81:1816-1829.e5. [PMID: 33639094 DOI: 10.1016/j.molcel.2021.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/28/2020] [Accepted: 02/01/2021] [Indexed: 10/24/2022]
Abstract
Alternative lengthening of telomeres (ALT) is a recombination process that maintains telomeres in the absence of telomerase and helps cancer cells to survive. Yeast has been used as a robust model of ALT; however, the inability to determine the frequency and structure of ALT survivors hinders understanding of the ALT mechanism. Here, using population and molecular genetics approaches, we overcome these problems and demonstrate that contrary to the current view, both RAD51-dependent and RAD51-independent mechanisms are required for a unified ALT survivor pathway. This conclusion is based on the calculation of ALT frequencies, as well as on ultra-long sequencing of ALT products that revealed hybrid sequences containing features attributed to both recombination pathways. Sequencing of ALT intermediates demonstrates that recombination begins with Rad51-mediated strand invasion to form DNA substrates that are matured by a Rad51-independent ssDNA annealing pathway. A similar unified ALT pathway may operate in other organisms, including humans.
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Affiliation(s)
- Zachary W Kockler
- Department of Biology, University of Iowa, Iowa City, IA 52245, USA; Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52245, USA
| | - Josep M Comeron
- Department of Biology, University of Iowa, Iowa City, IA 52245, USA; Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52245, USA.
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52245, USA; Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52245, USA.
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13
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CRISPR/Cas9 Induced Somatic Recombination at the CRTISO Locus in Tomato. Genes (Basel) 2020; 12:genes12010059. [PMID: 33396568 PMCID: PMC7824628 DOI: 10.3390/genes12010059] [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: 12/03/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 12/25/2022] Open
Abstract
Homologous recombination (HR) in somatic cells is not as well understood as meiotic recombination and is thought to be rare. In a previous study, we showed that Inter-Homologous Somatic Recombination (IHSR) can be achieved by targeted induction of DNA double-strand breaks (DSBs). Here, we designed a novel IHSR assay to investigate this phenomenon in greater depth. We utilized F1 hybrids from divergent parental lines, each with a different mutation at the Carotenoid isomerase (CRTISO) locus. IHSR events, namely crossover or gene conversion (GC), between the two CRTISO mutant alleles (tangerine color) can restore gene activity and be visualized as gain-of-function, wildtype (red) phenotypes. Our results show that out of four intron DSB targets tested, three showed DSB formation, as seen from non-homologous end-joining (NHEJ) footprints, but only one target generated putative IHSR events as seen by red sectors on tangerine fruits. F2 seeds were grown to test for germinal transmission of HR events. Two out of five F1 plants showing red sectors had their IHSR events germinally transmitted to F2, mainly as gene conversion. Six independent recombinant alleles were characterized: three had truncated conversion tracts with an average length of ~1 kb. Two alleles were formed by a crossover as determined by genotyping and characterized by whole genome sequencing. We discuss how IHSR can be used for future research and for the development of novel gene editing and precise breeding tools.
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14
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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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15
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Crickard JB, Kwon Y, Sung P, Greene EC. Rad54 and Rdh54 occupy spatially and functionally distinct sites within the Rad51-ssDNA presynaptic complex. EMBO J 2020; 39:e105705. [PMID: 32790929 PMCID: PMC7560196 DOI: 10.15252/embj.2020105705] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/13/2020] [Accepted: 07/29/2020] [Indexed: 12/21/2022] Open
Abstract
Rad54 and Rdh54 are closely related ATP-dependent motor proteins that participate in homologous recombination (HR). During HR, these enzymes functionally interact with the Rad51 presynaptic complex (PSC). Despite their importance, we know little about how they are organized within the PSC, or how their organization affects PSC function. Here, we use single-molecule optical microscopy and genetic analysis of chimeric protein constructs to evaluate the binding distributions of Rad54 and Rdh54 within the PSC. We find that Rad54 and Rdh54 have distinct binding sites within the PSC, which allow these proteins to act cooperatively as DNA sequences are aligned during homology search. Our data also reveal that Rad54 must bind to a specific location within the PSC, whereas Rdh54 retains its function in the repair of MMS-induced DNA damage even when recruited to the incorrect location. These findings support a model in which the relative binding sites of Rad54 and Rdh54 help to define their functions during mitotic HR.
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Affiliation(s)
- J Brooks Crickard
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
| | - Youngho Kwon
- Department of Biochemistry and Structural BiologyUniversity of Texas Health Science Center at San AntonioSan AntonioTXUSA
| | - Patrick Sung
- Department of Biochemistry and Structural BiologyUniversity of Texas Health Science Center at San AntonioSan AntonioTXUSA
| | - Eric C Greene
- Department of Biochemistry & Molecular BiophysicsColumbia UniversityNew YorkNYUSA
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16
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Gallagher DN, Pham N, Tsai AM, Janto NV, Choi J, Ira G, Haber JE. A Rad51-independent pathway promotes single-strand template repair in gene editing. PLoS Genet 2020; 16:e1008689. [PMID: 33057349 PMCID: PMC7591047 DOI: 10.1371/journal.pgen.1008689] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 10/27/2020] [Accepted: 08/03/2020] [Indexed: 01/26/2023] Open
Abstract
The Rad51/RecA family of recombinases perform a critical function in typical repair of double-strand breaks (DSBs): strand invasion of a resected DSB end into a homologous double-stranded DNA (dsDNA) template sequence to initiate repair. However, repair of a DSB using single stranded DNA (ssDNA) as a template, a common method of CRISPR/Cas9-mediated gene editing, is Rad51-independent. We have analyzed the genetic requirements for these Rad51-independent events in Saccharomyces cerevisiae by creating a DSB with the site-specific HO endonuclease and repairing the DSB with 80-nt single-stranded oligonucleotides (ssODNs), and confirmed these results by Cas9-mediated DSBs in combination with a bacterial retron system that produces ssDNA templates in vivo. We show that single strand template repair (SSTR), is dependent on Rad52, Rad59, Srs2 and the Mre11-Rad50-Xrs2 (MRX) complex, but unlike other Rad51-independent recombination events, independent of Rdh54. We show that Rad59 acts to alleviate the inhibition of Rad51 on Rad52's strand annealing activity both in SSTR and in single strand annealing (SSA). Gene editing is Rad51-dependent when double-stranded oligonucleotides of the same size and sequence are introduced as templates. The assimilation of mismatches during gene editing is dependent on the activity of Msh2, which acts very differently on the 3' side of the ssODN which can anneal directly to the resected DSB end compared to the 5' end. In addition DNA polymerase Polδ's 3' to 5' proofreading activity frequently excises a mismatch very close to the 3' end of the template. We further report that SSTR is accompanied by as much as a 600-fold increase in mutations in regions adjacent to the sequences directly undergoing repair. These DNA polymerase ζ-dependent mutations may compromise the accuracy of gene editing.
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Affiliation(s)
- Danielle N. Gallagher
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Nhung Pham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - Annie M. Tsai
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Nicolas V. Janto
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Jihyun Choi
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States of America
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA, United States of America
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17
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Sproul JS, Khost DE, Eickbush DG, Negm S, Wei X, Wong I, Larracuente AM. Dynamic Evolution of Euchromatic Satellites on the X Chromosome in Drosophila melanogaster and the simulans Clade. Mol Biol Evol 2020; 37:2241-2256. [PMID: 32191304 PMCID: PMC7403614 DOI: 10.1093/molbev/msaa078] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Satellite DNAs (satDNAs) are among the most dynamically evolving components of eukaryotic genomes and play important roles in genome regulation, genome evolution, and speciation. Despite their abundance and functional impact, we know little about the evolutionary dynamics and molecular mechanisms that shape satDNA distributions in genomes. Here, we use high-quality genome assemblies to study the evolutionary dynamics of two complex satDNAs, Rsp-like and 1.688 g/cm3, in Drosophila melanogaster and its three nearest relatives in the simulans clade. We show that large blocks of these repeats are highly dynamic in the heterochromatin, where their genomic location varies across species. We discovered that small blocks of satDNA that are abundant in X chromosome euchromatin are similarly dynamic, with repeats changing in abundance, location, and composition among species. We detail the proliferation of a rare satellite (Rsp-like) across the X chromosome in D. simulans and D. mauritiana. Rsp-like spread by inserting into existing clusters of the older, more abundant 1.688 satellite, in events likely facilitated by microhomology-mediated repair pathways. We show that Rsp-like is abundant on extrachromosomal circular DNA in D. simulans, which may have contributed to its dynamic evolution. Intralocus satDNA expansions via unequal exchange and the movement of higher order repeats also contribute to the fluidity of the repeat landscape. We find evidence that euchromatic satDNA repeats experience cycles of proliferation and diversification somewhat analogous to bursts of transposable element proliferation. Our study lays a foundation for mechanistic studies of satDNA proliferation and the functional and evolutionary consequences of satDNA movement.
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Affiliation(s)
- John S Sproul
- Department of Biology, University of Rochester, Rochester, NY
| | | | | | - Sherif Negm
- Department of Biology, University of Rochester, Rochester, NY
| | - Xiaolu Wei
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY
| | - Isaac Wong
- Department of Biology, University of Rochester, Rochester, NY
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18
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Hum YF, Jinks-Robertson S. Mismatch recognition and subsequent processing have distinct effects on mitotic recombination intermediates and outcomes in yeast. Nucleic Acids Res 2019; 47:4554-4568. [PMID: 30809658 PMCID: PMC6511840 DOI: 10.1093/nar/gkz126] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/12/2019] [Accepted: 02/23/2019] [Indexed: 01/25/2023] Open
Abstract
The post-replicative mismatch repair (MMR) system has anti-recombination activity that limits interactions between diverged sequences by recognizing mismatches in strand-exchange intermediates. In contrast to their equivalent roles during replication-error repair, mismatch recognition is more important for anti-recombination than subsequent mismatch processing. To obtain insight into this difference, ectopic substrates with 2% sequence divergence were used to examine mitotic recombination outcome (crossover or noncrossover; CO and NCO, respectively) and to infer molecular intermediates formed during double-strand break repair in Saccharomyces cerevisiae. Experiments were performed in an MMR-proficient strain, a strain with compromised mismatch-recognition activity (msh6Δ) and a strain that retained mismatch-recognition activity but was unable to process mismatches (mlh1Δ). While the loss of either mismatch binding or processing elevated the NCO frequency to a similar extent, CO events increased only when mismatch binding was compromised. The molecular features of NCOs, however, were altered in fundamentally different ways depending on whether mismatch binding or processing was eliminated. These data suggest a model in which mismatch recognition reverses strand-exchange intermediates prior to the initiation of end extension, while subsequent mismatch processing that is linked to end extension specifically destroys NCO intermediates that contain conflicting strand-discrimination signals for mismatch removal.
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Affiliation(s)
- Yee Fang Hum
- University Program in Genetics and Genomics, Duke University, Durham, NC, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
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19
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Heissl A, Betancourt AJ, Hermann P, Povysil G, Arbeithuber B, Futschik A, Ebner T, Tiemann-Boege I. The impact of poly-A microsatellite heterologies in meiotic recombination. Life Sci Alliance 2019; 2:2/2/e201900364. [PMID: 31023833 PMCID: PMC6485458 DOI: 10.26508/lsa.201900364] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/27/2019] [Accepted: 03/29/2019] [Indexed: 12/12/2022] Open
Abstract
Meiosis strongly influences the transmission and evolution of heterozygous poly-A repeats as measured experimentally in a large collection of single recombination products in a human hotspot. Meiotic recombination has strong, but poorly understood effects on short tandem repeat (STR) instability. Here, we screened thousands of single recombinant products with sperm typing to characterize the role of polymorphic poly-A repeats at a human recombination hotspot in terms of hotspot activity and STR evolution. We show that the length asymmetry between heterozygous poly-A’s strongly influences the recombination outcome: a heterology of 10 A’s (9A/19A) reduces the number of crossovers and elevates the frequency of non-crossovers, complex recombination products, and long conversion tracts. Moreover, the length of the heterology also influences the STR transmission during meiotic repair with a strong and significant insertion bias for the short heterology (6A/7A) and a deletion bias for the long heterology (9A/19A). In spite of this opposing insertion-/deletion-biased gene conversion, we find that poly-A’s are enriched at human recombination hotspots that could have important consequences in hotspot activation.
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Affiliation(s)
- Angelika Heissl
- Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | | | - Philipp Hermann
- Institute of Applied Statistics, Johannes Kepler University, Linz, Austria
| | - Gundula Povysil
- Institute of Bioinformatics, Johannes Kepler University, Linz, Austria
| | | | - Andreas Futschik
- Institute of Applied Statistics, Johannes Kepler University, Linz, Austria
| | - Thomas Ebner
- Department of Gynecology, Obstetrics and Gynecological Endocrinology, Kepler University Clinic, Linz, Austria
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20
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Dynamic Processing of Displacement Loops during Recombinational DNA Repair. Mol Cell 2019; 73:1255-1266.e4. [PMID: 30737186 DOI: 10.1016/j.molcel.2019.01.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 11/08/2018] [Accepted: 01/03/2019] [Indexed: 12/22/2022]
Abstract
Displacement loops (D-loops) are pivotal intermediates of homologous recombination (HR), a universal DNA double strand break (DSB) repair pathway. We developed a versatile assay for the physical detection of D-loops in vivo, which enabled studying the kinetics of their formation and defining the activities controlling their metabolism. Nascent D-loops are detected within 2 h of DSB formation and extended in a delayed fashion in a genetic system designed to preclude downstream repair steps. The majority of nascent D-loops are disrupted by two pathways: one supported by the Srs2 helicase and the other by the Mph1 helicase and the Sgs1-Top3-Rmi1 helicase-topoisomerase complex. Both pathways operate without significant overlap and are delineated by the Rad54 paralog Rdh54 in an ATPase-independent fashion. This study uncovers a layer of quality control of HR relying on nascent D-loop dynamics.
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21
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Klein HL, Bačinskaja G, Che J, Cheblal A, Elango R, Epshtein A, Fitzgerald DM, Gómez-González B, Khan SR, Kumar S, Leland BA, Marie L, Mei Q, Miné-Hattab J, Piotrowska A, Polleys EJ, Putnam CD, Radchenko EA, Saada AA, Sakofsky CJ, Shim EY, Stracy M, Xia J, Yan Z, Yin Y, Aguilera A, Argueso JL, Freudenreich CH, Gasser SM, Gordenin DA, Haber JE, Ira G, Jinks-Robertson S, King MC, Kolodner RD, Kuzminov A, Lambert SAE, Lee SE, Miller KM, Mirkin SM, Petes TD, Rosenberg SM, Rothstein R, Symington LS, Zawadzki P, Kim N, Lisby M, Malkova A. Guidelines for DNA recombination and repair studies: Cellular assays of DNA repair pathways. MICROBIAL CELL (GRAZ, AUSTRIA) 2019; 6:1-64. [PMID: 30652105 PMCID: PMC6334234 DOI: 10.15698/mic2019.01.664] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/29/2018] [Accepted: 09/14/2018] [Indexed: 12/29/2022]
Abstract
Understanding the plasticity of genomes has been greatly aided by assays for recombination, repair and mutagenesis. These assays have been developed in microbial systems that provide the advantages of genetic and molecular reporters that can readily be manipulated. Cellular assays comprise genetic, molecular, and cytological reporters. The assays are powerful tools but each comes with its particular advantages and limitations. Here the most commonly used assays are reviewed, discussed, and presented as the guidelines for future studies.
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Affiliation(s)
- Hannah L. Klein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Giedrė Bačinskaja
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Jun Che
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Anais Cheblal
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland
| | - Rajula Elango
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Anastasiya Epshtein
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Devon M. Fitzgerald
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Belén Gómez-González
- Centro Andaluz de BIología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, Seville, Spain
| | - Sharik R. Khan
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sandeep Kumar
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Léa Marie
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Qian Mei
- Systems, Synthetic and Physical Biology Graduate Program, Rice University, Houston, TX, USA
| | - Judith Miné-Hattab
- Institut Curie, PSL Research University, CNRS, UMR3664, F-75005 Paris, France
- Sorbonne Université, Institut Curie, CNRS, UMR3664, F-75005 Paris, France
| | - Alicja Piotrowska
- NanoBioMedical Centre, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
| | | | - Christopher D. Putnam
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Department of Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
| | | | - Anissia Ait Saada
- Institut Curie, PSL Research University, CNRS, UMR3348 F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Cynthia J. Sakofsky
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Mathew Stracy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Jun Xia
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Zhenxin Yan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yi Yin
- Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, NC USA
| | - Andrés Aguilera
- Centro Andaluz de BIología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla, Seville, Spain
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Catherine H. Freudenreich
- Department of Biology, Tufts University, Medford, MA USA
- Program in Genetics, Tufts University, Boston, MA, USA
| | - Susan M. Gasser
- Friedrich Miescher Institute for Biomedical Research (FMI), 4058 Basel, Switzerland
| | - Dmitry A. Gordenin
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Durham, NC, USA
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center Brandeis University, Waltham, MA, USA
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC USA
| | | | - Richard D. Kolodner
- Ludwig Institute for Cancer Research, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Moores-UCSD Cancer Center, University of California School of Medicine, San Diego, La Jolla, CA, USA
- Institute of Genomic Medicine, University of California School of Medicine, San Diego, La Jolla, CA, USA
| | - Andrei Kuzminov
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sarah AE Lambert
- Institut Curie, PSL Research University, CNRS, UMR3348 F-91405, Orsay, France
- University Paris Sud, Paris-Saclay University, CNRS, UMR3348, F-91405, Orsay, France
| | - Sang Eun Lee
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, USA
| | - Kyle M. Miller
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | | | - Thomas D. Petes
- Department of Molecular Genetics and Microbiology and University Program in Genetics and Genomics, Duke University Medical Center, Durham, NC USA
| | - Susan M. Rosenberg
- Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
- Systems, Synthetic and Physical Biology Graduate Program, Rice University, Houston, TX, USA
| | - Rodney Rothstein
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, USA
| | - Lorraine S. Symington
- Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Pawel Zawadzki
- NanoBioMedical Centre, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA, USA
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22
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Bourgeois L, Pyne ME, Martin VJJ. A Highly Characterized Synthetic Landing Pad System for Precise Multicopy Gene Integration in Yeast. ACS Synth Biol 2018; 7:2675-2685. [PMID: 30372609 DOI: 10.1021/acssynbio.8b00339] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A fundamental undertaking of metabolic engineering involves identifying and troubleshooting metabolic bottlenecks that arise from imbalances in pathway flux. To expedite the systematic screening of enzyme orthologs in conjunction with DNA copy number tuning, here we develop a simple and highly characterized CRISPR-Cas9 integration system in Saccharomyces cerevisiae. Our engineering strategy introduces a series of synthetic DNA landing pads (LP) into the S. cerevisiae genome to act as sites for high-level gene integration. LPs facilitate multicopy gene integration of one, two, three, or four DNA copies in a single transformation, thus providing precise control of DNA copy number. We applied our LP system to norcoclaurine synthase (NCS), an enzyme with poor kinetic properties involved in the first committed step of the production of high-value benzylisoquinoline alkaloids. The platform enabled rapid construction of a 40-strain NCS library by integrating ten NCS orthologs in four gene copies each. Six active NCS variants were identified, whereby production of ( S)-norcoclaurine could be further enhanced by increasing NCS copy number. We anticipate the LP system will aid in metabolic engineering efforts by providing strict control of gene copy number and expediting strain and pathway engineering campaigns.
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Affiliation(s)
- Leanne Bourgeois
- Department of Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
| | - Michael E. Pyne
- Department of Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
| | - Vincent J. J. Martin
- Department of Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
- Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec H3G 1M8, Canada
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23
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Tight Regulation of Srs2 Helicase Activity Is Crucial for Proper Functioning of DNA Repair Mechanisms. G3-GENES GENOMES GENETICS 2018. [PMID: 29531123 PMCID: PMC5940153 DOI: 10.1534/g3.118.200181] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Proper DNA damage repair is one of the most vital and fundamental functions of every cell. Several different repair mechanisms exist to deal with various types of DNA damage, in various stages of the cell cycle and under different conditions. Homologous recombination is one of the most important repair mechanisms in all organisms. Srs2, a regulator of homologous recombination, is a DNA helicase involved in DNA repair, cell cycle progression and genome integrity. Srs2 can remove Rad51 from ssDNA, and is thought to inhibit unscheduled recombination. However, Srs2 has to be precisely regulated, as failure to do so is toxic and can lead to cell death. We noticed that a very slight elevation of the levels of Srs2 (by addition of a single extra copy of the SRS2 gene) leads to hyper-sensitivity of yeast cells to methyl methanesulfonate (MMS, a DNA damaging agent). This effect is seen in haploid, but not in diploid, cells. We analyzed the mechanism that controls haploid/diploid sensitivity and arrived to the conclusion that the sensitivity requires the activity of RAD59 and RDH54, whose expression in diploid cells is repressed. We carried out a mutational analysis of Srs2 to determine the regions of the protein required for the sensitization to genotoxins. Interestingly, Srs2 needs the HR machinery and its helicase activity for its toxicity, but does not need to dismantle Rad51. Our work underscores the tight regulation that is required on the levels of Srs2 activity, and the fact that Srs2 helicase activity plays a more central role in DNA repair than the ability of Srs2 to dismantle Rad51 filaments.
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24
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Abstract
The repair of chromosomal double-strand breaks (DSBs) by homologous recombination is essential to maintain genome integrity. The key step in DSB repair is the RecA/Rad51-mediated process to match sequences at the broken end to homologous donor sequences that can be used as a template to repair the lesion. Here, in reviewing research about DSB repair, I consider the many factors that appear to play important roles in the successful search for homology by several homologous recombination mechanisms. See also the video abstract here: https://youtu.be/vm7-X5uIzS8.
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Affiliation(s)
- James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454-9110, USA
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25
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Hum YF, Jinks-Robertson S. DNA strand-exchange patterns associated with double-strand break-induced and spontaneous mitotic crossovers in Saccharomyces cerevisiae. PLoS Genet 2018; 14:e1007302. [PMID: 29579095 PMCID: PMC5886692 DOI: 10.1371/journal.pgen.1007302] [Citation(s) in RCA: 13] [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: 12/19/2017] [Revised: 04/05/2018] [Accepted: 03/08/2018] [Indexed: 11/24/2022] Open
Abstract
Mitotic recombination can result in loss of heterozygosity and chromosomal rearrangements that shape genome structure and initiate human disease. Engineered double-strand breaks (DSBs) are a potent initiator of recombination, but whether spontaneous events initiate with the breakage of one or both DNA strands remains unclear. In the current study, a crossover (CO)-specific assay was used to compare heteroduplex DNA (hetDNA) profiles, which reflect strand exchange intermediates, associated with DSB-induced versus spontaneous events in yeast. Most DSB-induced CO products had the two-sided hetDNA predicted by the canonical DSB repair model, with a switch in hetDNA position from one product to the other at the position of the break. Approximately 40% of COs, however, had hetDNA on only one side of the initiating break. This anomaly can be explained by a modified model in which there is frequent processing of an early invasion (D-loop) intermediate prior to extension of the invading end. Finally, hetDNA tracts exhibited complexities consistent with frequent expansion of the DSB into a gap, migration of strand-exchange junctions, and template switching during gap-filling reactions. hetDNA patterns in spontaneous COs isolated in either a wild-type background or in a background with elevated levels of reactive oxygen species (tsa1Δ mutant) were similar to those associated with the DSB-induced events, suggesting that DSBs are the major instigator of spontaneous mitotic recombination in yeast.
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Affiliation(s)
- Yee Fang Hum
- Department of Molecular Genetics and Microbiology and the University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology and the University Program in Genetics and Genomics, Duke University, Durham, North Carolina, United States of America
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26
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Piazza A, Koszul R, Heyer WD. A Proximity Ligation-Based Method for Quantitative Measurement of D-Loop Extension in S. cerevisiae. Methods Enzymol 2018. [PMID: 29523235 DOI: 10.1016/bs.mie.2017.11.024] [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] [Indexed: 01/03/2023]
Abstract
Homologous recombination faithfully restores the sequence information interrupted by a DNA double-strand break by referencing an intact DNA molecule as a template for repair DNA synthesis. DNA synthesis is primed from 3'-OH end of the invading DNA strand in the displacement loop (D-loop). Here, we describe a simple and quantitative proximity ligation-based assay to study the initiation of homologous recombination-associated DNA synthesis initiated at the D-loop and final product formation. The D-loop extension assay overcomes the semiquantitative nature and some limitations of the current PCR-based technique and facilitates the study of the recombination-associated DNA synthesis.
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Affiliation(s)
- Aurèle Piazza
- University of California, Davis, Davis, CA, United States; Institut Pasteur, Paris, France
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27
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Gallagher DN, Haber JE. Repair of a Site-Specific DNA Cleavage: Old-School Lessons for Cas9-Mediated Gene Editing. ACS Chem Biol 2018; 13:397-405. [PMID: 29083855 DOI: 10.1021/acschembio.7b00760] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CRISPR/Cas9-mediated gene editing may involve nonhomologous end-joining to create various insertion/deletions (indels) or may employ homologous recombination to modify precisely the target DNA sequence. Our understanding of these processes has been guided by earlier studies using other site-specific endonucleases, both in model organisms such as budding yeast and in mammalian cells. We briefly review what has been gleaned from such studies using the HO and I-SceI endonucleases and how these findings guide current gene editing strategies.
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Affiliation(s)
- Danielle N. Gallagher
- Rosenstiel Basic Medical
Sciences Research Center and Department of Biology, Brandeis University, Waltham, Massachusetts 22454-9110, United States
| | - James E. Haber
- Rosenstiel Basic Medical
Sciences Research Center and Department of Biology, Brandeis University, Waltham, Massachusetts 22454-9110, United States
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28
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Precision genome editing using synthesis-dependent repair of Cas9-induced DNA breaks. Proc Natl Acad Sci U S A 2017; 114:E10745-E10754. [PMID: 29183983 PMCID: PMC5740635 DOI: 10.1073/pnas.1711979114] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Genome editing, the introduction of precise changes in the genome, is revolutionizing our ability to decode the genome. Here we describe a simple method for genome editing in mammalian cells that takes advantage of an efficient mechanism for gene conversion that utilizes linear donors. We demonstrate that PCR fragments containing edits up to 1 kb require only 35-bp homology sequences to initiate repair of Cas9-induced double-stranded breaks in human cells and mouse embryos. We experimentally determine donor DNA design rules that maximize the recovery of edits without cloning or selection. The RNA-guided DNA endonuclease Cas9 has emerged as a powerful tool for genome engineering. Cas9 creates targeted double-stranded breaks (DSBs) in the genome. Knockin of specific mutations (precision genome editing) requires homology-directed repair (HDR) of the DSB by synthetic donor DNAs containing the desired edits, but HDR has been reported to be variably efficient. Here, we report that linear DNAs (single and double stranded) engage in a high-efficiency HDR mechanism that requires only ∼35 nucleotides of homology with the targeted locus to introduce edits ranging from 1 to 1,000 nucleotides. We demonstrate the utility of linear donors by introducing fluorescent protein tags in human cells and mouse embryos using PCR fragments. We find that repair is local, polarity sensitive, and prone to template switching, characteristics that are consistent with gene conversion by synthesis-dependent strand annealing. Our findings enable rational design of synthetic donor DNAs for efficient genome editing.
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29
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Schroeder JW, Yeesin P, Simmons LA, Wang JD. Sources of spontaneous mutagenesis in bacteria. Crit Rev Biochem Mol Biol 2017; 53:29-48. [PMID: 29108429 DOI: 10.1080/10409238.2017.1394262] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mutations in an organism's genome can arise spontaneously, that is, in the absence of exogenous stress and prior to selection. Mutations are often neutral or deleterious to individual fitness but can also provide genetic diversity driving evolution. Mutagenesis in bacteria contributes to the already serious and growing problem of antibiotic resistance. However, the negative impacts of spontaneous mutagenesis on human health are not limited to bacterial antibiotic resistance. Spontaneous mutations also underlie tumorigenesis and evolution of drug resistance. To better understand the causes of genetic change and how they may be manipulated in order to curb antibiotic resistance or the development of cancer, we must acquire a mechanistic understanding of the major sources of mutagenesis. Bacterial systems are particularly well-suited to studying mutagenesis because of their fast growth rate and the panoply of available experimental tools, but efforts to understand mutagenic mechanisms can be complicated by the experimental system employed. Here, we review our current understanding of mutagenic mechanisms in bacteria and describe the methods used to study mutagenesis in bacterial systems.
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Affiliation(s)
- Jeremy W Schroeder
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
| | - Ponlkrit Yeesin
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
| | - Lyle A Simmons
- b Department of Molecular, Cellular, and Developmental Biology , University of Michigan , Ann Arbor , MI , USA
| | - Jue D Wang
- a Department of Bacteriology , University of Wisconsin - Madison , Madison , WI , USA
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30
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Targeted recombination between homologous chromosomes for precise breeding in tomato. Nat Commun 2017; 8:15605. [PMID: 28548094 PMCID: PMC5458649 DOI: 10.1038/ncomms15605] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/05/2017] [Indexed: 01/10/2023] Open
Abstract
Homologous recombination (HR) between parental chromosomes occurs stochastically. Here, we report on targeted recombination between homologous chromosomes upon somatic induction of DNA double-strand breaks (DSBs) via CRISPR-Cas9. We demonstrate this via a visual and molecular assay whereby DSB induction between two alleles carrying different mutations in the PHYTOENE SYNTHASE (PSY1) gene results in yellow fruits with wild type red sectors forming via HR-mediated DSB repair. We also show that in heterozygote plants containing one psy1 allele immune and one sensitive to CRISPR, repair of the broken allele using the unbroken allele sequence template is a common outcome. In another assay, we show evidence of a somatically induced DSB in a cross between a psy1 edible tomato mutant and wild type Solanum pimpinellifolium, targeting only the S. pimpinellifolium allele. This enables characterization of germinally transmitted targeted somatic HR events, demonstrating that somatically induced DSBs can be exploited for precise breeding of crops. Targeted homologous recombination between parental chromosomes could facilitate precision breeding of crop plants. Here, Filler Hayut et al. show that CRISPR-Cas9 can be used to induce DNA double strand breaks in somatic tissue and achieve targeted recombination between homologs at an endogenous locus in tomato.
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31
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McVey M, Khodaverdian VY, Meyer D, Cerqueira PG, Heyer WD. Eukaryotic DNA Polymerases in Homologous Recombination. Annu Rev Genet 2017; 50:393-421. [PMID: 27893960 DOI: 10.1146/annurev-genet-120215-035243] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Homologous recombination (HR) is a central process to ensure genomic stability in somatic cells and during meiosis. HR-associated DNA synthesis determines in large part the fidelity of the process. A number of recent studies have demonstrated that DNA synthesis during HR is conservative, less processive, and more mutagenic than replicative DNA synthesis. In this review, we describe mechanistic features of DNA synthesis during different types of HR-mediated DNA repair, including synthesis-dependent strand annealing, break-induced replication, and meiotic recombination. We highlight recent findings from diverse eukaryotic organisms, including humans, that suggest both replicative and translesion DNA polymerases are involved in HR-associated DNA synthesis. Our focus is to integrate the emerging literature about DNA polymerase involvement during HR with the unique aspects of these repair mechanisms, including mutagenesis and template switching.
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Affiliation(s)
- Mitch McVey
- Department of Biology, Tufts University, Medford, Massachusetts 02155;
| | | | - Damon Meyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616; .,College of Health Sciences, California Northstate University, Rancho Cordova, California 95670
| | - Paula Gonçalves Cerqueira
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616;
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616; .,Department of Molecular and Cellular Biology, University of California, Davis, California 95616
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32
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Syed S, Desler C, Rasmussen LJ, Schmidt KH. A Novel Rrm3 Function in Restricting DNA Replication via an Orc5-Binding Domain Is Genetically Separable from Rrm3 Function as an ATPase/Helicase in Facilitating Fork Progression. PLoS Genet 2016; 12:e1006451. [PMID: 27923055 PMCID: PMC5140057 DOI: 10.1371/journal.pgen.1006451] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 10/31/2016] [Indexed: 11/21/2022] Open
Abstract
In response to replication stress cells activate the intra-S checkpoint, induce DNA repair pathways, increase nucleotide levels, and inhibit origin firing. Here, we report that Rrm3 associates with a subset of replication origins and controls DNA synthesis during replication stress. The N-terminal domain required for control of DNA synthesis maps to residues 186–212 that are also critical for binding Orc5 of the origin recognition complex. Deletion of this domain is lethal to cells lacking the replication checkpoint mediator Mrc1 and leads to mutations upon exposure to the replication stressor hydroxyurea. This novel Rrm3 function is independent of its established role as an ATPase/helicase in facilitating replication fork progression through polymerase blocking obstacles. Using quantitative mass spectrometry and genetic analyses, we find that the homologous recombination factor Rdh54 and Rad5-dependent error-free DNA damage bypass act as independent mechanisms on DNA lesions that arise when Rrm3 catalytic activity is disrupted whereas these mechanisms are dispensable for DNA damage tolerance when the replication function is disrupted, indicating that the DNA lesions generated by the loss of each Rrm3 function are distinct. Although both lesion types activate the DNA-damage checkpoint, we find that the resultant increase in nucleotide levels is not sufficient for continued DNA synthesis under replication stress. Together, our findings suggest a role of Rrm3, via its Orc5-binding domain, in restricting DNA synthesis that is genetically and physically separable from its established catalytic role in facilitating fork progression through replication blocks. When cells duplicate their genome, the replication machinery is constantly at risk of encountering obstacles, including unusual DNA structures, bound proteins, or transcribing polymerases and transcripts. Cells possess DNA helicases that facilitate movement of the replication fork through such obstacles. Here, we report the discovery that one of these DNA helicases, Rrm3, is also required for restricting DNA synthesis under replication stress. We find that the site in Rrm3 critical for this new replication function is also required for binding a subunit of the replication origin recognition complex, which raises the possibility that Rrm3 controls replication by affecting initiation. This is supported by our finding that Rrm3 associates with a subset of replication origins. Rrm3’s ability to restrict replication does not require its helicase activity or the phosphorylation site that regulates this activity. Notably, cells need error-free bypass pathways and homologous recombination to deal with DNA lesions that arise when the helicase function of Rrm3 is disrupted, but not when its replication function is disrupted. This indicates that the DNA lesions that form in the absence of the two distinct Rrm3 function are different, although both activate the DNA-damage checkpoint and are toxic to cells that lack the mediator of the replication checkpoint Mrc1.
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Affiliation(s)
- Salahuddin Syed
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
- Graduate Program in Cellular and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
| | - Claus Desler
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Lene J. Rasmussen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Kristina H. Schmidt
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida, Tampa, Florida, United States of America
- Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
- * E-mail:
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33
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Abstract
Double-strand breaks (DSBs) pose a severe challenge to genome integrity; consequently, cells have developed efficient mechanisms to repair DSBs through several pathways of homologous recombination and other nonhomologous end-joining processes. Much of our understanding of these pathways has come from the analysis of site-specific DSBs created by the HO endonuclease in the budding yeast Saccharomyces cerevisiae. I was fortunate to get in on the ground floor of analyzing the fate of synchronously induced DSBs through the study of what I coined "in vivo biochemistry." I have had the remarkable good fortune to profit from the development of new techniques that have permitted an ever more detailed dissection of these repair mechanisms, which are described here.
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Affiliation(s)
- James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02453;
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34
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The rate of meiotic gene conversion varies by sex and age. Nat Genet 2016; 48:1377-1384. [PMID: 27643539 PMCID: PMC5083143 DOI: 10.1038/ng.3669] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 08/16/2016] [Indexed: 12/14/2022]
Abstract
Meiotic recombination involves a combination of gene conversion and crossover events that, along with mutations, produce germline genetic diversity. Here we report the discovery of 3,176 SNP and 61 indel gene conversions. Our estimate of the non-crossover (NCO) gene conversion rate (G) is 7.0 for SNPs and 5.8 for indels per megabase per generation, and the GC bias is 67.6%. For indels, we demonstrate a 65.6% preference for the shorter allele. NCO gene conversions from mothers are longer than those from fathers, and G is 2.17 times greater in mothers. Notably, G increases with the age of mothers, but not the age of fathers. A disproportionate number of NCO gene conversions in older mothers occur outside double-strand break (DSB) regions and in regions with relatively low GC content. This points to age-related changes in the mechanisms of meiotic gene conversion in oocytes.
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35
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Jain S, Sugawara N, Haber JE. Role of Double-Strand Break End-Tethering during Gene Conversion in Saccharomyces cerevisiae. PLoS Genet 2016; 12:e1005976. [PMID: 27074148 PMCID: PMC4830573 DOI: 10.1371/journal.pgen.1005976] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 03/15/2016] [Indexed: 11/19/2022] Open
Abstract
Correct repair of DNA double-strand breaks (DSBs) is critical for maintaining genome stability. Whereas gene conversion (GC)-mediated repair is mostly error-free, repair by break-induced replication (BIR) is associated with non-reciprocal translocations and loss of heterozygosity. We have previously shown that a Recombination Execution Checkpoint (REC) mediates this competition by preventing the BIR pathway from acting on DSBs that can be repaired by GC. Here, we asked if the REC can also determine whether the ends that are engaged in a GC-compatible configuration belong to the same break, since repair involving ends from different breaks will produce potentially deleterious translocations. We report that the kinetics of repair are markedly delayed when the two DSB ends that participate in GC belong to different DSBs (termed Trans) compared to the case when both DSB ends come from the same break (Cis). However, repair in Trans still occurs by GC rather than BIR, and the overall efficiency of repair is comparable. Hence, the REC is not sensitive to the "origin" of the DSB ends. When the homologous ends for GC are in Trans, the delay in repair appears to reflect their tethering to sequences on the other side of the DSB that themselves recombine with other genomic locations with which they share sequence homology. These data support previous observations that the two ends of a DSB are usually tethered to each other and that this tethering facilitates both ends encountering the same donor sequence. We also found that the presence of homeologous/repetitive sequences in the vicinity of a DSB can distract the DSB end from finding its bona fide homologous donor, and that inhibition of GC by such homeologous sequences is markedly increased upon deleting Sgs1 but not Msh6.
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Affiliation(s)
- Suvi Jain
- Department of Biology and Rosenstiel Medical Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Neal Sugawara
- Department of Biology and Rosenstiel Medical Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - James E. Haber
- Department of Biology and Rosenstiel Medical Center, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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36
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Carvalho CMB, Lupski JR. Mechanisms underlying structural variant formation in genomic disorders. Nat Rev Genet 2016; 17:224-38. [PMID: 26924765 DOI: 10.1038/nrg.2015.25] [Citation(s) in RCA: 414] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With the recent burst of technological developments in genomics, and the clinical implementation of genome-wide assays, our understanding of the molecular basis of genomic disorders, specifically the contribution of structural variation to disease burden, is evolving quickly. Ongoing studies have revealed a ubiquitous role for genome architecture in the formation of structural variants at a given locus, both in DNA recombination-based processes and in replication-based processes. These reports showcase the influence of repeat sequences on genomic stability and structural variant complexity and also highlight the tremendous plasticity and dynamic nature of our genome in evolution, health and disease susceptibility.
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Affiliation(s)
- Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Centro de Pesquisas René Rachou - FIOCRUZ, Belo Horizonte, MG 30190-002, Brazil
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA.,Texas Children's Hospital, Houston, Texas 77030, USA
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37
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Rodgers K, McVey M. Error-Prone Repair of DNA Double-Strand Breaks. J Cell Physiol 2016; 231:15-24. [PMID: 26033759 DOI: 10.1002/jcp.25053] [Citation(s) in RCA: 240] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 05/20/2015] [Indexed: 12/14/2022]
Abstract
Preserving the integrity of the DNA double helix is crucial for the maintenance of genomic stability. Therefore, DNA double-strand breaks represent a serious threat to cells. In this review, we describe the two major strategies used to repair double strand breaks: non-homologous end joining and homologous recombination, emphasizing the mutagenic aspects of each. We focus on emerging evidence that homologous recombination, long thought to be an error-free repair process, can in fact be highly mutagenic, particularly in contexts requiring large amounts of DNA synthesis. Recent investigations have begun to illuminate the molecular mechanisms by which error-prone double-strand break repair can create major genomic changes, such as translocations and complex chromosome rearrangements. We highlight these studies and discuss proposed models that may explain some of the more extreme genetic changes observed in human cancers and congenital disorders.
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Affiliation(s)
- Kasey Rodgers
- Department of Biology, Tufts University, Medford, Massachusetts
| | - Mitch McVey
- Department of Biology, Tufts University, Medford, Massachusetts
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38
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Williams AL, Genovese G, Dyer T, Altemose N, Truax K, Jun G, Patterson N, Myers SR, Curran JE, Duggirala R, Blangero J, Reich D, Przeworski M. Non-crossover gene conversions show strong GC bias and unexpected clustering in humans. eLife 2015; 4. [PMID: 25806687 PMCID: PMC4404656 DOI: 10.7554/elife.04637] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 03/20/2015] [Indexed: 12/15/2022] Open
Abstract
Although the past decade has seen tremendous progress in our understanding of fine-scale recombination, little is known about non-crossover (NCO) gene conversion. We report the first genome-wide study of NCO events in humans. Using SNP array data from 98 meioses, we identified 103 sites affected by NCO, of which 50/52 were confirmed in sequence data. Overlap with double strand break (DSB) hotspots indicates that most of the events are likely of meiotic origin. We estimate that a site is involved in a NCO at a rate of 5.9 × 10(-6)/bp/generation, consistent with sperm-typing studies, and infer that tract lengths span at least an order of magnitude. Observed NCO events show strong allelic bias at heterozygous AT/GC SNPs, with 68% (58-78%) transmitting GC alleles (p = 5 × 10(-4)). Strikingly, in 4 of 15 regions with resequencing data, multiple disjoint NCO tracts cluster in close proximity (∼20-30 kb), a phenomenon not previously seen in mammals.
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Affiliation(s)
- Amy L Williams
- Department of Biological Sciences, Columbia University, New York, United States
| | - Giulio Genovese
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, United States
| | - Thomas Dyer
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, United States
| | - Nicolas Altemose
- Wellcome Trust Centre for Human Genetics, Oxford University, Oxford, United Kingdom
| | - Katherine Truax
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, United States
| | - Goo Jun
- Department of Biostatistics, University of Michigan, Ann Arbor, United States
| | - Nick Patterson
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, United States
| | - Simon R Myers
- Wellcome Trust Centre for Human Genetics, Oxford University, Oxford, United Kingdom
| | - Joanne E Curran
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, United States
| | - Ravi Duggirala
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, United States
| | - John Blangero
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, United States
| | - David Reich
- Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, United States
| | - Molly Przeworski
- Department of Biological Sciences, Columbia University, New York, United States
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39
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Anand RP, Tsaponina O, Greenwell PW, Lee CS, Du W, Petes TD, Haber JE. Chromosome rearrangements via template switching between diverged repeated sequences. Genes Dev 2014; 28:2394-406. [PMID: 25367035 PMCID: PMC4215184 DOI: 10.1101/gad.250258.114] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Anand et al. examined break-induced replication (BIR) and template switching between highly diverged sequences in S. cerevisiae, induced during repair of a site-specific double-strand break (DSB). Template switches between highly divergent sequences appear to be mechanistically distinct from the initial strand invasions that establish BIR. BIR traversing repeated DNA sequences frequently results in complex translocations analogous to those seen in mammalian cells. These results suggest that template switching among repeated genes is a potent driver of genome instability and evolution. Recent high-resolution genome analyses of cancer and other diseases have revealed the occurrence of microhomology-mediated chromosome rearrangements and copy number changes. Although some of these rearrangements appear to involve nonhomologous end-joining, many must have involved mechanisms requiring new DNA synthesis. Models such as microhomology-mediated break-induced replication (MM-BIR) have been invoked to explain these rearrangements. We examined BIR and template switching between highly diverged sequences in Saccharomyces cerevisiae, induced during repair of a site-specific double-strand break (DSB). Our data show that such template switches are robust mechanisms that give rise to complex rearrangements. Template switches between highly divergent sequences appear to be mechanistically distinct from the initial strand invasions that establish BIR. In particular, such jumps are less constrained by sequence divergence and exhibit a different pattern of microhomology junctions. BIR traversing repeated DNA sequences frequently results in complex translocations analogous to those seen in mammalian cells. These results suggest that template switching among repeated genes is a potent driver of genome instability and evolution.
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Affiliation(s)
- Ranjith P Anand
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA
| | - Olga Tsaponina
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA
| | - Patricia W Greenwell
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Cheng-Sheng Lee
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA
| | - Wei Du
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA
| | - Thomas D Petes
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - James E Haber
- Rosenstiel Basic Medical Sciences Research Center, Department of Biology, Brandeis University, Waltham, Massachusetts 02254, USA;
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40
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Yadav P, Harcy V, Argueso JL, Dominska M, Jinks-Robertson S, Kim N. Topoisomerase I plays a critical role in suppressing genome instability at a highly transcribed G-quadruplex-forming sequence. PLoS Genet 2014; 10:e1004839. [PMID: 25473964 PMCID: PMC4256205 DOI: 10.1371/journal.pgen.1004839] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/20/2014] [Indexed: 11/18/2022] Open
Abstract
G-quadruplex or G4 DNA is a non-B secondary DNA structure that comprises a stacked array of guanine-quartets. Cellular processes such as transcription and replication can be hindered by unresolved DNA secondary structures potentially endangering genome maintenance. As G4-forming sequences are highly frequent throughout eukaryotic genomes, it is important to define what factors contribute to a G4 motif becoming a hotspot of genome instability. Using a genetic assay in Saccharomyces cerevisiae, we previously demonstrated that a potential G4-forming sequence derived from a guanine-run containing immunoglobulin switch Mu (Sμ) region becomes highly unstable when actively transcribed. Here we describe assays designed to survey spontaneous genome rearrangements initiated at the Sμ sequence in the context of large genomic areas. We demonstrate that, in the absence of Top1, a G4 DNA-forming sequence becomes a strong hotspot of gross chromosomal rearrangements and loss of heterozygosity associated with mitotic recombination within the ∼20 kb or ∼100 kb regions of yeast chromosome V or III, respectively. Transcription confers a critical strand bias since genome rearrangements at the G4-forming Sμ are elevated only when the guanine-runs are located on the non-transcribed strand. The direction of replication and transcription, when in a head-on orientation, further contribute to the elevated genome instability at a potential G4 DNA-forming sequence. The implications of our identification of Top1 as a critical factor in suppression of instability associated with potential G4 DNA-forming sequences are discussed. Genome instability is not evenly distributed, but rather is highly elevated at certain genomic loci containing DNA sequences that can fold into non-canonical secondary structures. The four-stranded G-quadruplex or G4 DNA is one such DNA structure capable of instigating transcription and/or replication obstruction and subsequent genome instability. In this study, we used a reporter system to quantitatively measure the level of genome instability occurring at a G4 DNA motif integrated into the yeast genome. We showed that the disruption of Topoisomerase I function significantly elevated various types of genome instability at the highly transcribed G4 motif generating loss of heterozygosity and copy number alterations (deletions and duplications), both of which are frequently observed in cancer genomes.
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Affiliation(s)
- Puja Yadav
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Victoria Harcy
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Margaret Dominska
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- * E-mail:
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