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Yu Y, Wang X, Fox J, Li Q, Yu Y, Hastings PJ, Chen K, Ira G. RPA and Rad27 limit templated and inverted insertions at DNA breaks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583931. [PMID: 38496432 PMCID: PMC10942419 DOI: 10.1101/2024.03.07.583931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Formation of templated insertions at DNA double-strand breaks (DSBs) is very common in cancer cells. The mechanisms and enzymes regulating these events are largely unknown. Here, we investigated templated insertions in yeast at DSBs using amplicon sequencing across a repaired locus. We document very short (most ∼5-34 bp), templated inverted duplications at DSBs. They are generated through a foldback mechanism that utilizes microhomologies adjacent to the DSB. Enzymatic requirements suggest a hybrid mechanism wherein one end requires Polδ-mediated synthesis while the other end is captured by nonhomologous end joining (NHEJ). This process is exacerbated in mutants with low levels or mutated RPA ( rtt105 Δ; rfa1 -t33) or extensive resection mutant ( sgs1 Δ exo1 Δ). Templated insertions from various distant genomic locations also increase in these mutants as well as in rad27 Δ and originate from fragile regions of the genome. Among complex insertions, common events are insertions of two sequences, originating from the same locus and with inverted orientation. We propose that these inversions are also formed by microhomology-mediated template switching. Taken together, we propose that a shortage of RPA typical in cancer cells is one possible factor stimulating the formation of templated insertions.
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2
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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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3
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Sharma M, Larow VM, Dobychina N, Kessler DS, Krasilnikova MM, Yaklichkin S. The evolutionary loss of the Eh1 motif in FoxE1 in the lineage of placental mammals. PLoS One 2023; 18:e0296176. [PMID: 38150428 PMCID: PMC10752562 DOI: 10.1371/journal.pone.0296176] [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: 03/30/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
Forkhead box E1 (FoxE1) protein is a transcriptional regulator known to play a major role in the development of the thyroid gland. By performing sequence alignments, we detected a deletion in FoxE1, which occurred in the evolution of mammals, near the point of divergence of placental mammals. This deletion led to the loss of the majority of the Eh1 motif, which was important for interactions with transcriptional corepressors. To investigate a potential mechanism for this deletion, we analyzed replication through the deletion area in mammalian cells with two-dimensional gel electrophoresis, and in vitro, using a primer extension reaction. We demonstrated that the area of the deletion presented an obstacle for replication in both assays. The exact position of polymerization arrest in primer extension indicated that it was most likely caused by a quadruplex DNA structure. The quadruplex structure hypothesis is also consistent with the exact borders of the deletion. The exact roles of these evolutionary changes in FoxE1 family proteins are still to be determined.
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Affiliation(s)
- Mahak Sharma
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania, United States of America
| | - Victoria M. Larow
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania, United States of America
| | - Nataliia Dobychina
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Daniel S. Kessler
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Maria M. Krasilnikova
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, Pennsylvania, United States of America
| | - Sergey Yaklichkin
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
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4
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Ait Saada A, Guo W, Costa AB, Yang J, Wang J, Lobachev K. Widely spaced and divergent inverted repeats become a potent source of chromosomal rearrangements in long single-stranded DNA regions. Nucleic Acids Res 2023; 51:3722-3734. [PMID: 36919609 PMCID: PMC10164571 DOI: 10.1093/nar/gkad153] [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: 11/11/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/16/2023] Open
Abstract
DNA inverted repeats (IRs) are widespread across many eukaryotic genomes. Their ability to form stable hairpin/cruciform secondary structures is causative in triggering chromosome instability leading to several human diseases. Distance and sequence divergence between IRs are inversely correlated with their ability to induce gross chromosomal rearrangements (GCRs) because of a lesser probability of secondary structure formation and chromosomal breakage. In this study, we demonstrate that structural parameters that normally constrain the instability of IRs are overcome when the repeats interact in single-stranded DNA (ssDNA). We established a system in budding yeast whereby >73 kb of ssDNA can be formed in cdc13-707fs mutants. We found that in ssDNA, 12 bp or 30 kb spaced Alu-IRs show similarly high levels of GCRs, while heterology only beyond 25% suppresses IR-induced instability. Mechanistically, rearrangements arise after cis-interaction of IRs leading to a DNA fold-back and the formation of a dicentric chromosome, which requires Rad52/Rad59 for IR annealing as well as Rad1-Rad10, Slx4, Msh2/Msh3 and Saw1 proteins for nonhomologous tail removal. Importantly, using structural characteristics rendering IRs permissive to DNA fold-back in yeast, we found that ssDNA regions mapped in cancer genomes contain a substantial number of potentially interacting and unstable IRs.
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Affiliation(s)
- Anissia Ait Saada
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Wenying Guo
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Alex B Costa
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Jiaxin Yang
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Jianrong Wang
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI 48824, USA
| | - Kirill S Lobachev
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
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5
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Wang L, Zhang S, Fang J, Jin X, Mamut R, Li P. The Chloroplast Genome of the Lichen Photobiont Trebouxiophyceae sp. DW1 and Its Phylogenetic Implications. Genes (Basel) 2022; 13:genes13101840. [PMID: 36292725 PMCID: PMC9601494 DOI: 10.3390/genes13101840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/30/2022] [Accepted: 10/10/2022] [Indexed: 11/16/2022] Open
Abstract
Lichens are symbiotic associations of algae and fungi. The genetic mechanism of the symbiosis of lichens and the influence of symbiosis on the size and composition of the genomes of symbiotic algae have always been intriguing scientific questions explored by lichenologists. However, there were limited data on lichen genomes. Therefore, we isolated and purified a lichen symbiotic alga to obtain a single strain (Trebouxiophyceae sp. DW1), and then obtained its chloroplast genome information by next-generation sequencing (NGS). The chloroplast genome is 129,447 bp in length, and the GC content is 35.2%. Repetitive sequences with the length of 30–35 bp account for 1.27% of the total chloroplast genome. The simple sequence repeats are all mononucleotide repeats. Codon usage analysis showed that the genome tended to use codon ending in A/U. By comparing the length of different regions of Trebouxiophyceae genomes, we found that the changes in the length of exons, introns, and intergenic sequences affect the size of genomes. Trebouxiophyceae had an unstable chloroplast genome structure, with IRs repeatedly losing during evolution. Phylogenetic analysis showed that Trebouxiophyceae is paraphyletic, and Trebouxiophyceae sp. DW1 is sister to the clade of Koliella longiseta and Pabia signiensis.
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Affiliation(s)
- Lidan Wang
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
| | - Shenglu Zhang
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jinjin Fang
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
| | - Xinjie Jin
- College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Reyim Mamut
- College of Life Sciences and Technology, Xinjiang University, Urumchi 830046, China
- Correspondence: (R.M.); (P.L.)
| | - Pan Li
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
- Correspondence: (R.M.); (P.L.)
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High-throughput techniques enable advances in the roles of DNA and RNA secondary structures in transcriptional and post-transcriptional gene regulation. Genome Biol 2022; 23:159. [PMID: 35851062 PMCID: PMC9290270 DOI: 10.1186/s13059-022-02727-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/07/2022] [Indexed: 12/27/2022] Open
Abstract
The most stable structure of DNA is the canonical right-handed double helix termed B DNA. However, certain environments and sequence motifs favor alternative conformations, termed non-canonical secondary structures. The roles of DNA and RNA secondary structures in transcriptional regulation remain incompletely understood. However, advances in high-throughput assays have enabled genome wide characterization of some secondary structures. Here, we describe their regulatory functions in promoters and 3’UTRs, providing insights into key mechanisms through which they regulate gene expression. We discuss their implication in human disease, and how advances in molecular technologies and emerging high-throughput experimental methods could provide additional insights.
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Osia B, Twarowski J, Jackson T, Lobachev K, Liu L, Malkova A. Migrating bubble synthesis promotes mutagenesis through lesions in its template. Nucleic Acids Res 2022; 50:6870-6889. [PMID: 35748867 PMCID: PMC9262586 DOI: 10.1093/nar/gkac520] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/23/2022] [Accepted: 06/10/2022] [Indexed: 12/24/2022] Open
Abstract
Break-induced replication (BIR) proceeds via a migrating D-loop for hundreds of kilobases and is highly mutagenic. Previous studies identified long single-stranded (ss) nascent DNA that accumulates during leading strand synthesis to be a target for DNA damage and a primary source of BIR-induced mutagenesis. Here, we describe a new important source of mutagenic ssDNA formed during BIR: the ssDNA template for leading strand BIR synthesis formed during D-loop migration. Specifically, we demonstrate that this D-loop bottom template strand (D-BTS) is susceptible to APOBEC3A (A3A)-induced DNA lesions leading to mutations associated with BIR. Also, we demonstrate that BIR-associated ssDNA promotes an additional type of genetic instability: replication slippage between microhomologies stimulated by inverted DNA repeats. Based on our results we propose that these events are stimulated by both known sources of ssDNA formed during BIR, nascent DNA formed by leading strand synthesis, and the D-BTS that we describe here. Together we report a new source of mutagenesis during BIR that may also be shared by other homologous recombination pathways driven by D-loop repair synthesis.
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Affiliation(s)
| | | | - Tyler Jackson
- Department of Biology, University of Iowa, Iowa City, IA 52245, USA,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kirill Lobachev
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GE 30332, USA
| | - Liping Liu
- Department of Biology, University of Iowa, Iowa City, IA 52245, USA
| | - Anna Malkova
- To whom correspondence should be addressed. Tel: +1 319 384 1285;
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8
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Mak CH. Nucleic acid folding simulations using a physics-based atomistic free energy model. J Chem Phys 2022; 156:174114. [PMID: 35525642 DOI: 10.1063/5.0086304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Performing full-resolution atomistic simulations of nucleic acid folding has remained a challenge for biomolecular modeling. Understanding how nucleic acids fold and how they transition between different folded structures as they unfold and refold has important implications for biology. This paper reports a theoretical model and computer simulation of the ab initio folding of DNA inverted repeat sequences. The formulation is based on an all-atom conformational model of the sugar-phosphate backbone via chain closure, and it incorporates three major molecular-level driving forces-base stacking, counterion-induced backbone self-interactions, and base pairing-via separate analytical theories designed to capture and reproduce the effects of the solvent without requiring explicit water and ions in the simulation. To accelerate computational throughput, a mixed numerical/analytical algorithm for the calculation of the backbone conformational volume is incorporated into the Monte Carlo simulation, and special stochastic sampling techniques were employed to achieve the computational efficiency needed to fold nucleic acids from scratch. This paper describes implementation details, benchmark results, and the advantages and technical challenges with this approach.
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Affiliation(s)
- Chi H Mak
- Departments of Chemistry and Quantitative and Computational Biology, and Center of Applied Mathematical Sciences, University of Southern California, Los Angeles, California 90089, USA
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9
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Georgakopoulos-Soares I, Victorino J, Parada GE, Agarwal V, Zhao J, Wong HY, Umar MI, Elor O, Muhwezi A, An JY, Sanders SJ, Kwok CK, Inoue F, Hemberg M, Ahituv N. High-throughput characterization of the role of non-B DNA motifs on promoter function. CELL GENOMICS 2022; 2:100111. [PMID: 35573091 PMCID: PMC9105345 DOI: 10.1016/j.xgen.2022.100111] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 10/21/2021] [Accepted: 02/18/2022] [Indexed: 12/24/2022]
Abstract
lternative DNA conformations, termed non-B DNA structures, can affect transcription, but the underlying mechanisms and their functional impact have not been systematically characterized. Here, we used computational genomic analyses coupled with massively parallel reporter assays (MPRAs) to show that certain non-B DNA structures have a substantial effect on gene expression. Genomic analyses found that non-B DNA structures at promoters harbor an excess of germline variants. Analysis of multiple MPRAs, including a promoter library specifically designed to perturb non-B DNA structures, functionally validated that Z-DNA can significantly affect promoter activity. We also observed that biophysical properties of non-B DNA motifs, such as the length of Z-DNA motifs and the orientation of G-quadruplex structures relative to transcriptional direction, have a significant effect on promoter activity. Combined, their higher mutation rate and functional effect on transcription implicate a subset of non-B DNA motifs as major drivers of human gene-expression-associated phenotypes.
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Affiliation(s)
- Ilias Georgakopoulos-Soares
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Jesus Victorino
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), 28029 Madrid, Spain
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), 28029 Madrid, Spain
| | - Guillermo E. Parada
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, UK
- Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | | | - Jingjing Zhao
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Hei Yuen Wong
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Mubarak Ishaq Umar
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
| | - Orry Elor
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Allan Muhwezi
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, UK
| | - Joon-Yong An
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA, USA
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul, Republic of Korea
| | - Stephan J. Sanders
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
- Department of Psychiatry, UCSF Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Chun Kit Kwok
- Department of Chemistry and State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon Tong, Hong Kong SAR, China
- Shenzhen Research Institute of City University of Hong Kong, Shenzhen, China
| | - Fumitaka Inoue
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
| | - Martin Hemberg
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, UK
- Wellcome Trust Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
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10
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Protein innovation through template switching in the Saccharomyces cerevisiae lineage. Sci Rep 2021; 11:22558. [PMID: 34799587 PMCID: PMC8604942 DOI: 10.1038/s41598-021-01736-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 10/27/2021] [Indexed: 11/08/2022] Open
Abstract
DNA polymerase template switching between short, non-identical inverted repeats (IRs) is a genetic mechanism that leads to the homogenization of IR arms and to IR spacer inversion, which cause multinucleotide mutations (MNMs). It is unknown if and how template switching affects gene evolution. In this study, we performed a phylogenetic analysis to determine the effect of template switching between IR arms on coding DNA of Saccharomyces cerevisiae. To achieve this, perfect IRs that co-occurred with MNMs between a strain and its parental node were identified in S. cerevisiae strains. We determined that template switching introduced MNMs into 39 protein-coding genes through S. cerevisiae evolution, resulting in both arm homogenization and inversion of the IR spacer. These events in turn resulted in nonsynonymous substitutions and up to five neighboring amino acid replacements in a single gene. The study demonstrates that template switching is a powerful generator of multiple substitutions within codons. Additionally, some template switching events occurred more than once during S. cerevisiae evolution. Our findings suggest that template switching constitutes a general mutagenic mechanism that results in both nonsynonymous substitutions and parallel evolution, which are traditionally considered as evidence for positive selection, without the need for adaptive explanations.
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11
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Ali SS, Amoako-Attah I, Shao J, Kumi-Asare E, Meinhardt LW, Bailey BA. Mitochondrial Genomics of Six Cacao Pathogens From the Basidiomycete Family Marasmiaceae. Front Microbiol 2021; 12:752094. [PMID: 34777305 PMCID: PMC8581569 DOI: 10.3389/fmicb.2021.752094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/01/2021] [Indexed: 11/23/2022] Open
Abstract
Thread blight disease has recently been described as an emerging disease on cacao (Theobroma cacao) in Ghana. In Ghana, thread blight disease is caused by multiple species of the Marasmiaceae family: Marasmius tenuissimus, M. crinis-equi, M. palmivorus, and Marasmiellus scandens. Interestingly, two additional members of the Marasmiaceae; Moniliophthora roreri (frosty pod rot) and Moniliophthora perniciosa (witches’ broom disease), are major pathogens of cacao in the Western hemisphere. It is important to accurately characterize the genetic relationships among these economically important species in support of their disease management. We used data from Illumina NGS-based genome sequencing efforts to study the mitochondrial genomes (mitogenomes) of the four cacao thread blight associated pathogens from Ghana and compared them with published mitogenomes of Mon. roreri and Mon. perniciosa. There is a remarkable interspecies variation in mitogenome size within the six cacao-associated Marasmiaceae species, ranging from 43,121 to 109,103 bp. The differences in genome lengths are primarily due to the number and lengths of introns, differences in intergenic space, and differences in the size and numbers of unidentified ORFs (uORF). Among seven M. tenuissimus mitogenomes sequenced, there is variation in size and sequence pointing to divergent evolution patterns within the species. The intronic regions show a high degree of sequence variation compared to the conserved sequences of the 14 core genes. The intronic ORFs identified, regardless of species, encode GIY-YIG or LAGLIDADG domain-containing homing endonuclease genes. Phylogenetic relationships using the 14 core proteins largely mimic the phylogenetic relationships observed in gene order patterns, grouping M. tenuissimus with M. crinis-equi, and M. palmivorus with Mon. roreri and Mon. perniciosa, leaving Mar. scandens as an outlier. The results from this study provide evidence of independent expansion/contraction events and sequence diversification in each species and establish a foundation for further exploration of the evolutionary trajectory of the fungi in Marasmiaceae family.
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Affiliation(s)
- Shahin S Ali
- Sustainable Perennial Crops Laboratory, U. S. Department of Agriculture (USDA)/Agricultural Research Service (ARS), Beltsville Agricultural Research Center-West, Beltsville, MD, United States.,Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | | | - Jonathan Shao
- U. S. Department of Agriculture (USDA)/Agricultural Research Service (ARS), Beltsville, MD, United States
| | | | - Lyndel W Meinhardt
- Sustainable Perennial Crops Laboratory, U. S. Department of Agriculture (USDA)/Agricultural Research Service (ARS), Beltsville Agricultural Research Center-West, Beltsville, MD, United States
| | - Bryan A Bailey
- Sustainable Perennial Crops Laboratory, U. S. Department of Agriculture (USDA)/Agricultural Research Service (ARS), Beltsville Agricultural Research Center-West, Beltsville, MD, United States
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12
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Halliwell JA, Baker D, Judge K, Quail MA, Oliver K, Betteridge E, Skelton J, Andrews PW, Barbaric I. Nanopore Sequencing Indicates That Tandem Amplification of Chromosome 20q11.21 in Human Pluripotent Stem Cells Is Driven by Break-Induced Replication. Stem Cells Dev 2021; 30:578-586. [PMID: 33757297 PMCID: PMC8165465 DOI: 10.1089/scd.2021.0013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Copy number variants (CNVs) are genomic rearrangements implicated in numerous congenital and acquired diseases, including cancer. The appearance of culture-acquired CNVs in human pluripotent stem cells (PSCs) has prompted concerns for their use in regenerative medicine. A particular problem in PSC is the frequent occurrence of CNVs in the q11.21 region of chromosome 20. However, the exact mechanism of origin of this amplicon remains elusive due to the difficulty in delineating its sequence and breakpoints. Here, we have addressed this problem using long-read Nanopore sequencing of two examples of this CNV, present as duplication and as triplication. In both cases, the CNVs were arranged in a head-to-tail orientation, with microhomology sequences flanking or overlapping the proximal and distal breakpoints. These breakpoint signatures point to a mechanism of microhomology-mediated break-induced replication in CNV formation, with surrounding Alu sequences likely contributing to the instability of this genomic region.
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Affiliation(s)
- Jason A Halliwell
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Duncan Baker
- Sheffield Diagnostic Genetic Services, Sheffield Children's Hospital, Sheffield, United Kingdom
| | - Kim Judge
- Department of Sequencing R & D, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Michael A Quail
- Department of Sequencing R & D, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Karen Oliver
- Department of Sequencing R & D, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Emma Betteridge
- Department of Sequencing R & D, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Jason Skelton
- Department of Sequencing R & D, Wellcome Sanger Institute, Hinxton, United Kingdom
| | - Peter W Andrews
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
| | - Ivana Barbaric
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
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13
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Ait Saada A, Costa AB, Sheng Z, Guo W, Haber JE, Lobachev K. Structural parameters of palindromic repeats determine the specificity of nuclease attack of secondary structures. Nucleic Acids Res 2021; 49:3932-3947. [PMID: 33772579 PMCID: PMC8053094 DOI: 10.1093/nar/gkab168] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/24/2021] [Accepted: 03/02/2021] [Indexed: 12/15/2022] Open
Abstract
Palindromic sequences are a potent source of chromosomal instability in many organisms and are implicated in the pathogenesis of human diseases. In this study, we investigate which nucleases are responsible for cleavage of the hairpin and cruciform structures and generation of double-strand breaks at inverted repeats in Saccharomyces cerevisiae. We demonstrate that the involvement of structure-specific nucleases in palindrome fragility depends on the distance between inverted repeats and their transcriptional status. The attack by the Mre11 complex is constrained to hairpins with loops <9 nucleotides. This restriction is alleviated upon RPA depletion, indicating that RPA controls the stability and/or formation of secondary structures otherwise responsible for replication fork stalling and DSB formation. Mus81-Mms4 cleavage of cruciforms occurs at divergently but not convergently transcribed or nontranscribed repeats. Our study also reveals the third pathway for fragility at perfect and quasi-palindromes, which involves cruciform resolution during the G2 phase of the cell cycle.
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Affiliation(s)
- Anissia Ait Saada
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GE 30332, USA
| | - Alex B Costa
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GE 30332, USA
| | - Ziwei Sheng
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GE 30332, USA
| | - Wenying Guo
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GE 30332, USA
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Waltham, MA 02454-9110, USA
| | - Kirill S Lobachev
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GE 30332, USA
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14
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Ghiselli F, Gomes-Dos-Santos A, Adema CM, Lopes-Lima M, Sharbrough J, Boore JL. Molluscan mitochondrial genomes break the rules. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200159. [PMID: 33813887 DOI: 10.1098/rstb.2020.0159] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The first animal mitochondrial genomes to be sequenced were of several vertebrates and model organisms, and the consistency of genomic features found has led to a 'textbook description'. However, a more broad phylogenetic sampling of complete animal mitochondrial genomes has found many cases where these features do not exist, and the phylum Mollusca is especially replete with these exceptions. The characterization of full mollusc mitogenomes required considerable effort involving challenging molecular biology, but has created an enormous catalogue of surprising deviations from that textbook description, including wide variation in size, radical genome rearrangements, gene duplications and losses, the introduction of novel genes, and a complex system of inheritance dubbed 'doubly uniparental inheritance'. Here, we review the extraordinary variation in architecture, molecular functioning and intergenerational transmission of molluscan mitochondrial genomes. Such features represent a great potential for the discovery of biological history, processes and functions that are novel for animal mitochondrial genomes. This provides a model system for studying the evolution and the manifold roles that mitochondria play in organismal physiology, and many ways that the study of mitochondrial genomes are useful for phylogeny and population biology. This article is part of the Theo Murphy meeting issue 'Molluscan genomics: broad insights and future directions for a neglected phylum'.
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Affiliation(s)
- Fabrizio Ghiselli
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Italy
| | - André Gomes-Dos-Santos
- CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, and Department of Biology, Faculty of Sciences, University of Porto, Portugal
| | - Coen M Adema
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, USA
| | - Manuel Lopes-Lima
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal
| | - Joel Sharbrough
- Department of Biology, Colorado State University, Fort Collins, USA
| | - Jeffrey L Boore
- Providence St Joseph Health and the Institute for Systems Biology, Seattle, USA
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15
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Svetec Miklenić M, Svetec IK. Palindromes in DNA-A Risk for Genome Stability and Implications in Cancer. Int J Mol Sci 2021; 22:2840. [PMID: 33799581 PMCID: PMC7999016 DOI: 10.3390/ijms22062840] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 02/07/2023] Open
Abstract
A palindrome in DNA consists of two closely spaced or adjacent inverted repeats. Certain palindromes have important biological functions as parts of various cis-acting elements and protein binding sites. However, many palindromes are known as fragile sites in the genome, sites prone to chromosome breakage which can lead to various genetic rearrangements or even cell death. The ability of certain palindromes to initiate genetic recombination lies in their ability to form secondary structures in DNA which can cause replication stalling and double-strand breaks. Given their recombinogenic nature, it is not surprising that palindromes in the human genome are involved in genetic rearrangements in cancer cells as well as other known recurrent translocations and deletions associated with certain syndromes in humans. Here, we bring an overview of current understanding and knowledge on molecular mechanisms of palindrome recombinogenicity and discuss possible implications of DNA palindromes in carcinogenesis. Furthermore, we overview the data on known palindromic sequences in the human genome and efforts to estimate their number and distribution, as well as underlying mechanisms of genetic rearrangements specific palindromic sequences cause.
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Affiliation(s)
| | - Ivan Krešimir Svetec
- Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia;
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16
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Variable Number Tandem Repeats in the Mitochondrial DNA of Lentinula edodes. Genes (Basel) 2019; 10:genes10070542. [PMID: 31319586 PMCID: PMC6679062 DOI: 10.3390/genes10070542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/13/2019] [Accepted: 07/15/2019] [Indexed: 11/17/2022] Open
Abstract
Variable number tandem repeats (VNTRs) in mitochondrial DNA (mtDNA) of Lentinula edodes are of interest for their role in mtDNA variation and their application as genetic marker. Sequence analysis of three L. edodes mtDNAs revealed the presence of VNTRs of two categories. Type I VNTRs consist of two types of repeat units in a symmetric distribution, whereas Type II VNTRs contain tandemly arrayed repeats of 7- or 17-bp DNA sequences. The number of repeat units was variable depending on the mtDNA of different strains. Using the variations in VNTRs as a mitochondrial marker and the A mating type as a nuclear type marker, we demonstrated that one of the two nuclei in the donor dikaryon preferentially enters into the monokaryotic cytoplasm to establish a new dikaryon which still retains the mitochondria of the monokaryon in the individual mating. Interestingly, we found 6 VNTRs with newly added repeat units from the 22 mates, indicating that elongation of VNTRs occurs during replication of mtDNA. This, together with comparative analysis of the repeating pattern, enables us to propose a mechanistic model that explains the elongation of Type I VNTRs through reciprocal incorporation of basic repeat units, 5’-TCCCTTTAGGG-3’ and its complementary sequence (5’-CCCTAAAGGGA-3’).
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17
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Todd RT, Wikoff TD, Forche A, Selmecki A. Genome plasticity in Candida albicans is driven by long repeat sequences. eLife 2019; 8:45954. [PMID: 31172944 PMCID: PMC6591007 DOI: 10.7554/elife.45954] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 06/07/2019] [Indexed: 11/13/2022] Open
Abstract
Genome rearrangements resulting in copy number variation (CNV) and loss of heterozygosity (LOH) are frequently observed during the somatic evolution of cancer and promote rapid adaptation of fungi to novel environments. In the human fungal pathogen Candida albicans, CNV and LOH confer increased virulence and antifungal drug resistance, yet the mechanisms driving these rearrangements are not completely understood. Here, we unveil an extensive array of long repeat sequences (65-6499 bp) that are associated with CNV, LOH, and chromosomal inversions. Many of these long repeat sequences are uncharacterized and encompass one or more coding sequences that are actively transcribed. Repeats associated with genome rearrangements are predominantly inverted and separated by up to ~1.6 Mb, an extraordinary distance for homology-based DNA repair/recombination in yeast. These repeat sequences are a significant source of genome plasticity across diverse strain backgrounds including clinical, environmental, and experimentally evolved isolates, and represent previously uncharacterized variation in the reference genome.
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Affiliation(s)
- Robert T Todd
- Creighton University Medical School, Omaha, United States
| | - Tyler D Wikoff
- Creighton University Medical School, Omaha, United States
| | | | - Anna Selmecki
- Creighton University Medical School, Omaha, United States
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18
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Zhang L, Kong L. iRSpot-PDI: Identification of recombination spots by incorporating dinucleotide property diversity information into Chou's pseudo components. Genomics 2019; 111:457-464. [DOI: 10.1016/j.ygeno.2018.03.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 02/27/2018] [Accepted: 03/03/2018] [Indexed: 12/11/2022]
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19
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Kaushal S, Freudenreich CH. The role of fork stalling and DNA structures in causing chromosome fragility. Genes Chromosomes Cancer 2019; 58:270-283. [PMID: 30536896 DOI: 10.1002/gcc.22721] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/13/2018] [Accepted: 12/03/2018] [Indexed: 12/19/2022] Open
Abstract
Alternative non-B form DNA structures, also called secondary structures, can form in certain DNA sequences under conditions that produce single-stranded DNA, such as during replication, transcription, and repair. Direct links between secondary structure formation, replication fork stalling, and genomic instability have been found for many repeated DNA sequences that cause disease when they expand. Common fragile sites (CFSs) are known to be AT-rich and break under replication stress, yet the molecular basis for their fragility is still being investigated. Over the past several years, new evidence has linked both the formation of secondary structures and transcription to fork stalling and fragility of CFSs. How these two events may synergize to cause fragility and the role of nuclease cleavage at secondary structures in rare and CFSs are discussed here. We also highlight evidence for a new hypothesis that secondary structures at CFSs not only initiate fragility but also inhibit healing, resulting in their characteristic appearance.
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Affiliation(s)
- Simran Kaushal
- Department of Biology, Tufts University, Medford, Massachusetts
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford, Massachusetts.,Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, Massachusetts
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20
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Georgakopoulos-Soares I, Morganella S, Jain N, Hemberg M, Nik-Zainal S. Noncanonical secondary structures arising from non-B DNA motifs are determinants of mutagenesis. Genome Res 2018; 28:1264-1271. [PMID: 30104284 PMCID: PMC6120622 DOI: 10.1101/gr.231688.117] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 07/12/2018] [Indexed: 12/15/2022]
Abstract
Somatic mutations show variation in density across cancer genomes. Previous studies have shown that chromatin organization and replication time domains are correlated with, and thus predictive of, this variation. Here, we analyze 1809 whole-genome sequences from 10 cancer types to show that a subset of repetitive DNA sequences, called non-B motifs that predict noncanonical secondary structure formation can independently account for variation in mutation density. Combined with epigenetic factors and replication timing, the variance explained can be improved to 43%-76%. Approximately twofold mutation enrichment is observed directly within non-B motifs, is focused on exposed structural components, and is dependent on physical properties that are optimal for secondary structure formation. Therefore, there is mounting evidence that secondary structures arising from non-B motifs are not simply associated with increased mutation density-they are possibly causally implicated. Our results suggest that they are determinants of mutagenesis and increase the likelihood of recurrent mutations in the genome. This analysis calls for caution in the interpretation of recurrent mutations and highlights the importance of taking non-B motifs that can simply be inferred from the reference sequence into consideration in background models of mutability henceforth.
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Affiliation(s)
| | - Sandro Morganella
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, United Kingdom
| | - Naman Jain
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Martin Hemberg
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, United Kingdom
| | - Serena Nik-Zainal
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, United Kingdom
- East Anglian Medical Genetics Service, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 2QQ, United Kingdom
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21
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Ramakrishnan S, Kockler Z, Evans R, Downing BD, Malkova A. Single-strand annealing between inverted DNA repeats: Pathway choice, participating proteins, and genome destabilizing consequences. PLoS Genet 2018; 14:e1007543. [PMID: 30091972 PMCID: PMC6103520 DOI: 10.1371/journal.pgen.1007543] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 08/21/2018] [Accepted: 07/06/2018] [Indexed: 11/19/2022] Open
Abstract
Double strand DNA breaks (DSBs) are dangerous events that can result from various causes including environmental assaults or the collapse of DNA replication. While the efficient and precise repair of DSBs is essential for cell survival, faulty repair can lead to genetic instability, making the choice of DSB repair an important step. Here we report that inverted DNA repeats (IRs) placed near a DSB can channel its repair from an accurate pathway that leads to gene conversion to instead a break-induced replication (BIR) pathway that leads to genetic instabilities. The effect of IRs is explained by their ability to form unusual DNA structures when present in ssDNA that is formed by DSB resection. We demonstrate that IRs can form two types of unusual DNA structures, and the choice between these structures depends on the length of the spacer separating IRs. In particular, IRs separated by a long (1-kb) spacer are predominantly involved in inter-molecular single-strand annealing (SSA) leading to the formation of inverted dimers; IRs separated by a short (12-bp) spacer participate in intra-molecular SSA, leading to the formation of fold-back (FB) structures. Both of these structures interfere with an accurate DSB repair by gene conversion and channel DSB repair into BIR, which promotes genomic destabilization. We also report that different protein complexes participate in the processing of FBs containing short (12-bp) versus long (1-kb) ssDNA loops. Specifically, FBs with short loops are processed by the MRX-Sae2 complex, whereas the Rad1-Rad10 complex is responsible for the processing of long loops. Overall, our studies uncover the mechanisms of genomic destabilization resulting from re-routing DSB repair into unusual pathways by IRs. Given the high abundance of IRs in the human genome, our findings may contribute to the understanding of IR-mediated genomic destabilization associated with human disease. Efficient and accurate repair of double-strand DNA breaks (DSBs), resulting from the exposure of cells to ionizing radiation or various chemicals, is crucial for cell survival. Conversely, faulty DSB repair can generate genomic instability that can lead to birth defects or cancer in humans. Here we demonstrate that inverted DNA repeats (IRs) placed in the vicinity of a DSB, interfere with the accurate repair of DSBs and promote genomic rearrangements and chromosome loss. This results from annealing between inverted repeats, located either in different DNA molecules or in the same molecule. In addition, we describe a new role for the Rad1-Rad10 protein complex in processing fold-back (FB) structures formed by intra-molecular annealing involving IRs separated by long spacers. In contrast, FBs with short spacers are processed by the Mre11-Rad50-Xrs2/-Sae2 complex. Overall, we describe several pathways of DSB promoted interaction between IRs that can lead to genomic instability. Given the large number of IRs in the human genome, our findings are relevant to the mechanisms driving genomic destabilization in humans contributing to the development of cancer and other diseases.
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Affiliation(s)
- Sreejith Ramakrishnan
- Department of Biology, University of Iowa, Iowa City, IA, United States of America
- Indiana University Purdue University Indianapolis, Indianapolis, IN, United States of America
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Zachary Kockler
- Department of Biology, University of Iowa, Iowa City, IA, United States of America
| | - Robert Evans
- Indiana University Purdue University Indianapolis, Indianapolis, IN, United States of America
| | - Brandon D. Downing
- Indiana University Purdue University Indianapolis, Indianapolis, IN, United States of America
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA, United States of America
- Indiana University Purdue University Indianapolis, Indianapolis, IN, United States of America
- * E-mail:
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22
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Kshirsagar R, Ghodke I, Muniyappa K. Saccharomyces cerevisiae Red1 protein exhibits nonhomologous DNA end-joining activity and potentiates Hop1-promoted pairing of double-stranded DNA. J Biol Chem 2017. [PMID: 28642366 DOI: 10.1074/jbc.m117.796425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Elucidation of the function of synaptonemal complex (SC) in Saccharomyces cerevisiae has mainly focused on in vivo analysis of recombination-defective meiotic mutants. Consequently, significant gaps remain in the mechanistic understanding of the activities of various SC proteins and the functional relationships among them. S. cerevisiae Hop1 and Red1 are essential structural components of the SC axial/lateral elements. Previous studies have demonstrated that Hop1 is a structure-selective DNA-binding protein exhibiting high affinity for the Holliday junction and promoting DNA bridging, condensation, and pairing between double-stranded DNA molecules. However, the exact mode of action of Red1 remains unclear, although it is known to interact with Hop1 and to suppress the spore viability defects of hop1 mutant alleles. Here, we report the purification and functional characterization of the full-length Red1 protein. Our results revealed that Red1 forms a stable complex with Hop1 in vitro and provided quantitative insights into their physical interactions. Mechanistically, Red1 preferentially associated with the Holliday junction and 3-way junction rather than with single- or double-stranded DNA with overhangs. Although Hop1 and Red1 exhibited similar binding affinities toward several DNA substrates, the two proteins displayed some significant differences. Notably, Red1, by itself, lacked DNA-pairing ability; however, it potentiated Hop1-promoted intermolecular pairing between double-stranded DNA molecules. Moreover, Red1 exhibited nonhomologous DNA end-joining activity, thus revealing an unexpected role for Red1 in recombination-based DNA repair. Collectively, this study presents the first direct insights into Red1's mode of action and into the mechanism underlying its role in chromosome synapsis and recombination.
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Affiliation(s)
- Rucha Kshirsagar
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Indrajeet Ghodke
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - K Muniyappa
- From the Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
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23
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Wang Y, Huang JM. Lirex: A Package for Identification of Long Inverted Repeats in Genomes. GENOMICS PROTEOMICS & BIOINFORMATICS 2017; 15:141-146. [PMID: 28392477 PMCID: PMC5414712 DOI: 10.1016/j.gpb.2017.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/04/2017] [Accepted: 01/22/2017] [Indexed: 11/30/2022]
Abstract
Long inverted repeats (LIRs) are evolutionarily and functionally important structures in genomes because of their involvement in RNA interference, DNA recombination, and gene duplication. Identification of LIRs is highly complicated when mismatches and indels between the repeats are permitted. Long inverted repeat explorer (Lirex) was developed and introduced in this report. Written in Java, Lirex provides a user-friendly interface and allows users to specify LIR searching criteria, such as length of the region, as well as pattern and size of the repeats. Recombinogenic LIRs can be selected on the basis of mismatch rate and internal spacer size from identified LIRs. Lirex, as a cross-platform tool to identify LIRs in a genome, may assist in designing following experiments to explore the function of LIRs. Our tool can identify more LIRs than other LIR searching tools. Lirex is publicly available at http://124.16.219.129/Lirex.
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Affiliation(s)
- Yong Wang
- Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China.
| | - Jiao-Mei Huang
- Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China
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24
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Using weighted features to predict recombination hotspots in Saccharomyces cerevisiae. J Theor Biol 2015; 382:15-22. [DOI: 10.1016/j.jtbi.2015.06.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 06/04/2015] [Accepted: 06/20/2015] [Indexed: 01/06/2023]
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25
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Putman AI, Tredway LP, Carbone I. Characterization and distribution of mating-type genes of the turfgrass pathogen Sclerotinia homoeocarpa on a global scale. Fungal Genet Biol 2015; 81:25-40. [PMID: 26049125 DOI: 10.1016/j.fgb.2015.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 05/27/2015] [Accepted: 05/28/2015] [Indexed: 01/23/2023]
Abstract
Sclerotinia homoeocarpa F.T. Bennett is a filamentous member of Ascomycota that causes dollar spot, the most economically important disease of turfgrass worldwide. We sequenced and characterized the mating-type (MAT) locus of four recently-collected contemporary strains causing dollar spot, four historical type strains used to describe the fungus, and three species of Rutstroemiaceae. Moreover, we developed a multiplex PCR assay to screen 1019 contemporary isolates for mating-type. The organization of the MAT loci of all strains examined could be classified into one of four categories: (1) putatively heterothallic, as exemplified by all contemporary strains and three of four historical type strains; (2) putatively heterothallic with a deleted putative gene in the MAT1-2 idiomorph, as detected in strains from two recently-collected populations in the United Kingdom that show more similarity to historical strains; (3) putatively homothallic with close physical linkage between MAT1-1-1 and MAT1-2-1, as found in one historical type strain of S. homoeocarpa and two strains of Rutstroemia cuniculi; and (4) an unresolved but apparently homothallic organization in which strains contained both MAT1-1-1 and MAT1-2-1 but linkage between these genes and between the two flanking genes could not be confirmed, as identified in R. paludosa and Poculum henningsianum. In contemporary S. homoeocarpa populations there was no significant difference in the frequency of the two mating types in clone-corrected samples when analyzed on regional and local scales, suggesting sex may be possible in this pathogen. However, two isolates from Italy and twenty from California were heterokaryotic for both complete heterothallic MAT idiomorphs. Results from this study contribute to knowledge about mating systems in filamentous fungi and enhance our understanding of the evolution and biology of an important plant pathogen.
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Affiliation(s)
- Alexander I Putman
- Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695-7616, United States.
| | - Lane P Tredway
- Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695-7616, United States
| | - Ignazio Carbone
- Center for Integrated Fungal Research, Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695-7244, United States
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26
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Aygun N. Correlations between long inverted repeat (LIR) features, deletion size and distance from breakpoint in human gross gene deletions. Sci Rep 2015; 5:8300. [PMID: 25657065 PMCID: PMC4319165 DOI: 10.1038/srep08300] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/14/2015] [Indexed: 11/09/2022] Open
Abstract
Long inverted repeats (LIRs) have been shown to induce genomic deletions in yeast. In this study, LIRs were investigated within ±10 kb spanning each breakpoint from 109 human gross deletions, using Inverted Repeat Finder (IRF) software. LIR number was significantly higher at the breakpoint regions, than in control segments (P < 0.001). In addition, it was found that strong correlation between 5' and 3' LIR numbers, suggesting contribution to DNA sequence evolution (r = 0.85, P < 0.001). 138 LIR features at ±3 kb breakpoints in 89 (81%) of 109 gross deletions were evaluated. Significant correlations were found between distance from breakpoint and loop length (r = -0.18, P < 0.05) and stem length (r = -0.18, P < 0.05), suggesting DNA strands are potentially broken in locations closer to bigger LIRs. In addition, bigger loops cause larger deletions (r = 0.19, P < 0.05). Moreover, loop length (r = 0.29, P < 0.02) and identity between stem copies (r = 0.30, P < 0.05) of 3' LIRs were more important in larger deletions. Consequently, DNA breaks may form via LIR-induced cruciform structure during replication. DNA ends may be later repaired by non-homologous end-joining (NHEJ), with following deletion.
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Affiliation(s)
- Nevim Aygun
- Department of Medical Biology, Faculty of Medicine, Dokuz Eylul University, Inciralti, Izmir, Turkey
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27
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Aguileta G, de Vienne DM, Ross ON, Hood ME, Giraud T, Petit E, Gabaldón T. High variability of mitochondrial gene order among fungi. Genome Biol Evol 2015; 6:451-65. [PMID: 24504088 PMCID: PMC3942027 DOI: 10.1093/gbe/evu028] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
From their origin as an early alpha proteobacterial endosymbiont to their current state as cellular organelles, large-scale genomic reorganization has taken place in the mitochondria of all main eukaryotic lineages. So far, most studies have focused on plant and animal mitochondrial (mt) genomes (mtDNA), but fungi provide new opportunities to study highly differentiated mtDNAs. Here, we analyzed 38 complete fungal mt genomes to investigate the evolution of mtDNA gene order among fungi. In particular, we looked for evidence of nonhomologous intrachromosomal recombination and investigated the dynamics of gene rearrangements. We investigated the effect that introns, intronic open reading frames (ORFs), and repeats may have on gene order. Additionally, we asked whether the distribution of transfer RNAs (tRNAs) evolves independently to that of mt protein-coding genes. We found that fungal mt genomes display remarkable variation between and within the major fungal phyla in terms of gene order, genome size, composition of intergenic regions, and presence of repeats, introns, and associated ORFs. Our results support previous evidence for the presence of mt recombination in all fungal phyla, a process conspicuously lacking in most Metazoa. Overall, the patterns of rearrangements may be explained by the combined influences of recombination (i.e., most likely nonhomologous and intrachromosomal), accumulated repeats, especially at intergenic regions, and to a lesser extent, mobile element dynamics.
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Affiliation(s)
- Gabriela Aguileta
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Spain
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28
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Excision of unstable artificial gene-specific inverted repeats mediates scar-free gene deletions in Escherichia coli. Appl Biochem Biotechnol 2014; 175:1858-67. [PMID: 25427592 DOI: 10.1007/s12010-014-1402-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/12/2014] [Indexed: 01/13/2023]
Abstract
Inverted repeat and palindromic sequences have the propensity to form non-beta cruciform structures during DNA replication, leading to perturbations within the genome or plasmid replicon. In this study, the tolerance of the Escherichia coli genome to inverted repeat sequences from 25 to 1200 bp was investigated. Genomic inverted repeats were readily created via the homologous insertion of an overlap extension PCR product containing a gene-specific region of the genome together with thyA coding sequence, creating inverted repeat sequences of various lengths flanking the thyA selection marker in the resulting genome. Inverted repeat sequences below 100 bp were stably propagated, while those above and up to 1200 bp were found to be transiently unstable under auxotrophic thymine selection. Excision efficiency improves with increases of the inverted repeat until 600-800 bp, indicating that the genomic stability of inverted repeat sequences is due to secondary structure formation. Its effectiveness of creating precise and scar-free gene deletions was further demonstrated by deleting a number of genes in E. coli. The procedure can be readily adapted for sequence integration and point mutations in E. coli genome. It also has the potential for applications on other bacteria for efficient gene deletions.
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29
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Genome-wide high-resolution mapping of chromosome fragile sites in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2014; 111:E2210-8. [PMID: 24799712 DOI: 10.1073/pnas.1406847111] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In mammalian cells, perturbations in DNA replication result in chromosome breaks in regions termed "fragile sites." Using DNA microarrays, we mapped recombination events and chromosome rearrangements induced by reduced levels of the replicative DNA polymerase-α in the yeast Saccharomyces cerevisiae. We found that the recombination events were nonrandomly associated with a number of structural/sequence motifs that correlate with paused DNA replication forks, including replication-termination sites (TER sites) and binding sites for the helicase Rrm3p. The pattern of gene-conversion events associated with cross-overs suggests that most of the DNA lesions that initiate recombination between homologs are double-stranded DNA breaks induced during S or G2 of the cell cycle, in contrast to spontaneous recombination events that are initiated by double-stranded DNA breaks formed prior to replication. Low levels of DNA polymerase-α also induced very high rates of aneuploidy, as well as chromosome deletions and duplications. Most of the deletions and duplications had Ty retrotransposons at their breakpoints.
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Zhang Y, Saini N, Sheng Z, Lobachev KS. Genome-wide screen reveals replication pathway for quasi-palindrome fragility dependent on homologous recombination. PLoS Genet 2013; 9:e1003979. [PMID: 24339793 PMCID: PMC3855049 DOI: 10.1371/journal.pgen.1003979] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 10/12/2013] [Indexed: 02/07/2023] Open
Abstract
Inverted repeats capable of forming hairpin and cruciform structures present a threat to chromosomal integrity. They induce double strand breaks, which lead to gross chromosomal rearrangements, the hallmarks of cancers and hereditary diseases. Secondary structure formation at this motif has been proposed to be the driving force for the instability, albeit the mechanisms leading to the fragility are not well-understood. We carried out a genome-wide screen to uncover the genetic players that govern fragility of homologous and homeologous Alu quasi-palindromes in the yeast Saccharomyces cerevisiae. We found that depletion or lack of components of the DNA replication machinery, proteins involved in Fe-S cluster biogenesis, the replication-pausing checkpoint pathway, the telomere maintenance complex or the Sgs1-Top3-Rmi1 dissolvasome augment fragility at Alu-IRs. Rad51, a component of the homologous recombination pathway, was found to be required for replication arrest and breakage at the repeats specifically in replication-deficient strains. These data demonstrate that Rad51 is required for the formation of breakage-prone secondary structures in situations when replication is compromised while another mechanism operates in DSB formation in replication-proficient strains. Inverted repeats are found in many eukaryotic genomes including humans. They have a potential to cause chromosomal breakage and rearrangements that contribute to genome polymorphism and the development of diseases. Instability of inverted repeats is accounted for by their propensity to adopt DNA secondary structures that is negatively affected by the distance between the repeats and level of sequence divergence. However, the genetic factors that promote the abnormal structure formation or affect the ability of the repeats to break are largely unknown. Here, using a genome-wide screen we identified 38 mutants that destabilize imperfect human inverted Alu repeats and predispose them to breakage. The proteins that are required to maintain repeat stability belong to the core of the DNA replication machinery and to the accessory proteins that help replication fork to move through the difficult templates. Remarkably, when replication machinery is compromised, the proteins involved in homologous recombination promote the formation of secondary structures and replication block thereby triggering breakage at the inverted repeats. These results reveal a powerful pathway for the destabilization of chromosomes containing inverted repeats that requires the activity of homologous recombination.
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Affiliation(s)
- Yu Zhang
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Natalie Saini
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Ziwei Sheng
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
| | - Kirill S. Lobachev
- School of Biology and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia, United States of America
- * E-mail:
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Senda M, Nishimura S, Kasai A, Yumoto S, Takada Y, Tanaka Y, Ohnishi S, Kuroda T. Comparative analysis of the inverted repeat of a chalcone synthase pseudogene between yellow soybean and seed coat pigmented mutants. BREEDING SCIENCE 2013; 63:384-92. [PMID: 24399910 PMCID: PMC3859349 DOI: 10.1270/jsbbs.63.384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/17/2013] [Indexed: 05/13/2023]
Abstract
In soybean, the I gene inhibits pigmentation over the entire seed coat, resulting in yellow seeds. It is thought that this suppression of seed coat pigmentation is due to naturally occurring RNA silencing of chalcone synthase genes (CHS silencing). Fully pigmented seeds can be found among harvested yellow seeds at a very low percentage. These seed coat pigmented (scp) mutants are generated from yellow soybeans by spontaneous recessive mutation of the I gene. A candidate for the I gene, GmIRCHS, contains a perfect inverted repeat (IR) of a CHS pseudogene (pseudoCHS3) and transcripts of GmIRCHS form a double-stranded CHS RNA that potentially triggers CHS silencing. One CHS gene, ICHS1, is located 680 bp downstream of GmIRCHS. Here, the GmIRCHS-ICHS1 cluster was compared in scp mutants of various origins. In these mutants, sequence divergence in the cluster resulted in complete or partial loss of GmIRCHS in at least the pseudoCHS3 region. This result is consistent with the notion that the IR of pseudoCHS3 is sufficient to induce CHS silencing, and further supports that GmIRCHS is the I gene.
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Affiliation(s)
- Mineo Senda
- Faculty of Agriculture and Life Sciences, Hirosaki University,
3 Bunkyo-cho, Hirosaki, Aomori 036-8561,
Japan
- Corresponding author (e-mail: )
| | - Satsuki Nishimura
- Faculty of Agriculture and Life Sciences, Hirosaki University,
3 Bunkyo-cho, Hirosaki, Aomori 036-8561,
Japan
| | - Atsushi Kasai
- Faculty of Agriculture and Life Sciences, Hirosaki University,
3 Bunkyo-cho, Hirosaki, Aomori 036-8561,
Japan
| | - Setsuzo Yumoto
- Research Support Center, National Agricultural Research Center for Tohoku Region,
Yotsuya, Daisen, Akita 014-0102,
Japan
| | - Yoshitake Takada
- National Agricultural Research Organization (NARO) Western Region Agricultural Research Center,
1-3-1 Senyu, Zentsuji, Kagawa 765-8508,
Japan
| | - Yoshinori Tanaka
- Hokkaido Research Organization Tokachi Agricultural Experiment Station,
S9-2 Shinsei, Memuro, Kasai, Hokkaido 082-0081,
Japan
| | - Shizen Ohnishi
- Hokkaido Research Organization Kitami Agricultural Experiment Station,
52 Yayoi, Kunneppu, Tokoro, Hokkaido 099-1406,
Japan
| | - Tomohisa Kuroda
- Niigata Agricultural Research Institute,
857 Nagakura-machi, Nagaoka, Niigata 940-0826,
Japan
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Yang JN, Seluanov A, Gorbunova V. Mitochondrial inverted repeats strongly correlate with lifespan: mtDNA inversions and aging. PLoS One 2013; 8:e73318. [PMID: 24069185 PMCID: PMC3775743 DOI: 10.1371/journal.pone.0073318] [Citation(s) in RCA: 24] [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: 03/25/2013] [Accepted: 07/29/2013] [Indexed: 01/13/2023] Open
Abstract
Mitochondrial defects are implicated in aging and in a multitude of age-related diseases, such as cancer, heart failure, Parkinson's disease, and Huntington's disease. However, it is still unclear how mitochondrial defects arise under normal physiological conditions. Mitochondrial DNA (mtDNA) deletions caused by direct repeats (DRs) are implicated in the formation of mitochondrial defects, however, mitochondrial DRs show relatively weak (Pearson's r = -0.22, p<0.002; Spearman's ρ = -0.12, p = 0.1) correlation with maximum lifespan (MLS). Here we report a stronger correlation (Pearson's r = -0.55, p<10(-16); Spearman's ρ = -0.52, p<10(-14)) between mitochondrial inverted repeats (IRs) and lifespan across 202 species of mammals. We show that, in wild type mice under normal conditions, IRs cause inversions, which arise by replication-dependent mechanism. The inversions accumulate with age in the brain and heart. Our data suggest that IR-mediated inversions are more mutagenic than DR-mediated deletions in mtDNA, and impose stronger constraint on lifespan. Our study identifies IR-induced mitochondrial genome instability during mtDNA replication as a potential cause for mitochondrial defects.
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Affiliation(s)
- Jiang-Nan Yang
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Andrei Seluanov
- Department of Biology, University of Rochester, Rochester, New York, United States of America
- * E-mail: (VG); (AS)
| | - Vera Gorbunova
- Department of Biology, University of Rochester, Rochester, New York, United States of America
- * E-mail: (VG); (AS)
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Lim C, Luhe AL, JingYing CT, Balagurunathan B, Wu J, Zhao H. Size of gene specific inverted repeat--dependent gene deletion In Saccharomyces cerevisiae. PLoS One 2013; 8:e72137. [PMID: 23977230 PMCID: PMC3748122 DOI: 10.1371/journal.pone.0072137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/08/2013] [Indexed: 01/15/2023] Open
Abstract
We describe here an approach for rapidly producing scar-free and precise gene deletions in S. cerevisiae with high efficiency. Preparation of the disruption gene cassette in this approach was simply performed by overlap extension-PCR of an invert repeat of a partial or complete sequence of the targeted gene with URA3. Integration of the prepared disruption gene cassette to the designated position of a target gene leads to the formation of a mutagenesis cassette within the yeast genome, which consists of a URA3 gene flanked by the targeted gene and its inverted repeat between two short identical direct repeats. The inherent instability of the inverted sequences in close proximity facilitates the self-excision of the entire mutagenesis cassette deposited in the genome and promotes homologous recombination resulting in a seamless deletion via a single transformation. This rapid assembly circumvents the difficulty during preparation of disruption gene cassettes composed of two inverted repeats of the URA3, which requires the engineering of unique restriction sites for subsequent digestion and T4 DNA ligation in vitro. We further identified that the excision of the entire mutagenesis cassette flanked by two DRs in the transformed S. cerevisiae is dependent on the length of the inverted repeat of which a minimum of 800 bp is required for effective gene deletion. The deletion efficiency improves with the increase of the inverted repeat till 1.2 kb. Finally, the use of gene-specific inverted repeats of target genes enables simultaneous gene deletions. The procedure has the potential for application on other yeast strains to achieve precise and efficient removal of gene sequences.
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Affiliation(s)
- Chanyuen Lim
- Industrial Biotechnology Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
| | - Annette Lin Luhe
- Industrial Biotechnology Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
| | - Crystal Tear JingYing
- Industrial Biotechnology Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
| | - Balaji Balagurunathan
- Process Sciences and Modeling Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
| | - Jinchuan Wu
- Industrial Biotechnology Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
| | - Hua Zhao
- Industrial Biotechnology Division, Institute of Chemical and Engineering Sciences, Agency for Science, Technology and Research (A*STAR), Jurong Island, Singapore
- * E-mail:
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St. Charles J, Petes TD. High-resolution mapping of spontaneous mitotic recombination hotspots on the 1.1 Mb arm of yeast chromosome IV. PLoS Genet 2013; 9:e1003434. [PMID: 23593029 PMCID: PMC3616911 DOI: 10.1371/journal.pgen.1003434] [Citation(s) in RCA: 69] [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: 12/04/2012] [Accepted: 02/20/2013] [Indexed: 11/18/2022] Open
Abstract
Although homologous recombination is an important pathway for the repair of double-stranded DNA breaks in mitotically dividing eukaryotic cells, these events can also have negative consequences, such as loss of heterozygosity (LOH) of deleterious mutations. We mapped about 140 spontaneous reciprocal crossovers on the right arm of the yeast chromosome IV using single-nucleotide-polymorphism (SNP) microarrays. Our mapping and subsequent experiments demonstrate that inverted repeats of Ty retrotransposable elements are mitotic recombination hotspots. We found that the mitotic recombination maps on the two homologs were substantially different and were unrelated to meiotic recombination maps. Additionally, about 70% of the DNA lesions that result in LOH are likely generated during G1 of the cell cycle and repaired during S or G2. We also show that different genetic elements are associated with reciprocal crossover conversion tracts depending on the cell cycle timing of the initiating DSB. Double-strand breaks (DSBs) are DNA lesions that can be fatal to a cell if left unrepaired. They can be caused by exogenous sources, such as gamma radiation, or endogenous stresses, such as high levels of transcription. Yeast cells primarily repair DSBs that are initiated outside of meiosis by mitotic recombination, which can result in physical exchanges between chromosomes, known as crossovers. We created a mitotic recombination map of one chromosome arm, representing 10% of the genome. This recombination map allows us to determine which regions of the chromosome arm are more susceptible to DNA damage than other regions. We were able to determine that most DSBs that result in detectable genomic changes were initiated prior to DNA replication and that some secondary DNA structures can be recombination hotspots. Recombination can also occur during meiosis, as a method of ensuring proper chromosome segregation. However, previously reported meiotic recombination maps have no correlation with our mitotic recombination map.
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Affiliation(s)
- Jordan St. Charles
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Thomas D. Petes
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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35
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Lambert S, Carr AM. Impediments to replication fork movement: stabilisation, reactivation and genome instability. Chromosoma 2013; 122:33-45. [DOI: 10.1007/s00412-013-0398-9] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 02/11/2013] [Accepted: 02/11/2013] [Indexed: 01/02/2023]
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Compositional bias is a major determinant of the distribution pattern and abundance of palindromes in Drosophila melanogaster. J Mol Evol 2012; 75:130-40. [PMID: 23138634 DOI: 10.1007/s00239-012-9527-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Palindromic sequences are important DNA motifs related to gene regulation, DNA replication and recombination, and thus, investigating the evolutionary forces shaping the distribution pattern and abundance of palindromes in the genome is substantially important. In this article, we analyzed the abundance of palindromes in the genome, and then explored the possible effects of several genomic factors on the palindrome distribution and abundance in Drosophila melanogaster. Our results show that the palindrome abundance in D. melanogaster deviates from random expectation and the uneven distribution of palindromes across the genome is associated with local GC content, recombination rate, and coding exon density. Our data suggest that base composition is the major determinant of the distribution pattern and abundance of palindromes and the correlation between palindrome density and recombination is a side-product of the effect of compositional bias on the palindrome abundance.
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37
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Abstract
In addition to the canonical double helix, DNA can fold into various other inter- and intramolecular secondary structures. Although many such structures were long thought to be in vitro artefacts, bioinformatics demonstrates that DNA sequences capable of forming these structures are conserved throughout evolution, suggesting the existence of non-B-form DNA in vivo. In addition, genes whose products promote formation or resolution of these structures are found in diverse organisms, and a growing body of work suggests that the resolution of DNA secondary structures is critical for genome integrity. This Review focuses on emerging evidence relating to the characteristics of G-quadruplex structures and the possible influence of such structures on genomic stability and cellular processes, such as transcription.
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38
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Ho B, Baker PM, Singh S, Shih SJ, Vaughan AT. Localized DNA cleavage secondary to genotoxic exposure adjacent to an Alu inverted repeat. Genes Chromosomes Cancer 2012; 51:501-9. [PMID: 22334386 DOI: 10.1002/gcc.21938] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 01/05/2012] [Indexed: 01/12/2023] Open
Abstract
Radiation is a potent inducer of DNA damage leading to both random DNA loss and mutation. As part of a study focused on the mechanism whereby cells undergo loss of heterozygosity (LOH), a region of common LOH telomeric termination at 11q24 was observed in clones of H292 mucoepidermoid cells established after irradiation (IR). A 10-kbp region including the telomeric extent of LOH termination was analyzed after IR using six sets of ligation-mediated polymerase chain reaction (PCR) primers to detect the presence of DNA breaks. A cluster of DNA breaks was detected that closely mapped to the telomeric extent of LOH and which were observed up to 8 hr after IR. Repeating the experiment in the presence of the inhibitor of apoptosis, zVAD.fmk, did not change the location or amount of cleavage. A similar distribution of breaks was also seen in the MCF-10A breast cancer cell line after IR. Further inspection of the involved region showed that 22/32 and 7/7 DNA breaks found in H292 and MCF-10A cells, respectively, were located either in or immediately adjacent to an AluSx1 sequence, itself ≈ 1 kbp 5' to an AluSq2 that was in an inverted orientation to the AluSx1. The region between the inverted Alu repeats was notable for both DNAse hypersensitivity and an open chromatin conformation inferred from histone modification data. These factors may contribute to genomic instability at this location.
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Affiliation(s)
- Bay Ho
- Department of Radiation Oncology, University of California at Davis, Sacramento, CA 95817, USA
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Clapham KR, Yu TW, Ganesh VS, Barry B, Chan Y, Mei D, Parrini E, Funalot B, Dupuis L, Nezarati MM, du Souich C, van Karnebeek C, Guerrini R, Walsh CA. FLNA genomic rearrangements cause periventricular nodular heterotopia. Neurology 2012; 78:269-78. [PMID: 22238415 DOI: 10.1212/wnl.0b013e31824365e4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To identify copy number variant (CNV) causes of periventricular nodular heterotopia (PNH) in patients for whom FLNA sequencing is negative. METHODS Screening of 35 patients from 33 pedigrees on an Affymetrix 6.0 microarray led to the identification of one individual bearing a CNV that disrupted FLNA. FLNA-disrupting CNVs were also isolated in 2 other individuals by multiplex ligation probe amplification. These 3 cases were further characterized by high-resolution oligo array comparative genomic hybridization (CGH), and the precise junctional breakpoints of the rearrangements were identified by PCR amplification and sequencing. RESULTS We report 3 cases of PNH caused by nonrecurrent genomic rearrangements that disrupt one copy of FLNA. The first individual carried a 113-kb deletion that removes all but the first exon of FLNA. A second patient harbored a complex rearrangement including a deletion of the 3' end of FLNA accompanied by a partial duplication event. A third patient bore a 39-kb deletion encompassing all of FLNA and the neighboring gene EMD. High-resolution oligo array CGH of the FLNA locus suggests distinct molecular mechanisms for each of these rearrangements, and implicates nearby low copy repeats in their pathogenesis. CONCLUSIONS These results demonstrate that FLNA is prone to pathogenic rearrangements, and highlight the importance of screening for CNVs in individuals with PNH lacking FLNA point mutations.
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Affiliation(s)
- K R Clapham
- Harvard-MIT Division of Health Sciences and Technology, Boston, MA, USA
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40
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Nair NU, Zhao H. Mutagenic Inverted Repeats Assisted Genome Engineering (MIRAGE) in Saccharomyces cerevisiae: deletion of gal7. Methods Mol Biol 2012; 834:63-73. [PMID: 22144353 DOI: 10.1007/978-1-61779-483-4_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
MIRAGE is a unique in vivo genome editing technique that exploits the inherent instability of inverted repeats (palindromes) in the Saccharomyces cerevisiae chromosome. As a technique able to quickly create deletions as well as precise point mutations, it is valuable in applications that require creation of designer strains of this yeast. In particular, it has various potential applications in metabolic engineering, systems biology, synthetic biology, and molecular genetics.
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Affiliation(s)
- Nikhil U Nair
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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41
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Sequence-dependent prediction of recombination hotspots in Saccharomyces cerevisiae. J Theor Biol 2012; 293:49-54. [DOI: 10.1016/j.jtbi.2011.10.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 10/04/2011] [Accepted: 10/04/2011] [Indexed: 11/18/2022]
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Ramreddy T, Sachidanandam R, Strick TR. Real-time detection of cruciform extrusion by single-molecule DNA nanomanipulation. Nucleic Acids Res 2011; 39:4275-83. [PMID: 21266478 PMCID: PMC3105387 DOI: 10.1093/nar/gkr008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
During cruciform extrusion, a DNA inverted repeat unwinds and forms a four-way junction in which two of the branches consist of hairpin structures obtained by self-pairing of the inverted repeats. Here, we use single-molecule DNA nanomanipulation to monitor in real-time cruciform extrusion and rewinding. This allows us to determine the size of the cruciform to nearly base pair accuracy and its kinetics with second-scale time resolution. We present data obtained with two different inverted repeats, one perfect and one imperfect, and extend single-molecule force spectroscopy to measure the torque dependence of cruciform extrusion and rewinding kinetics. Using mutational analysis and a simple two-state model, we find that in the transition state intermediate only the B-DNA located between the inverted repeats (and corresponding to the unpaired apical loop) is unwound, implying that initial stabilization of the four-way (or Holliday) junction is rate-limiting. We thus find that cruciform extrusion is kinetically regulated by features of the hairpin loop, while rewinding is kinetically regulated by features of the stem. These results provide mechanistic insight into cruciform extrusion and help understand the structural features that determine the relative stability of the cruciform and B-form states.
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Affiliation(s)
- T Ramreddy
- Institut Jacques Monod, CNRS UMR 7592, University of Paris - Diderot, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
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Friedreich's ataxia (GAA)n•(TTC)n repeats strongly stimulate mitotic crossovers in Saccharomyces cerevisae. PLoS Genet 2011; 7:e1001270. [PMID: 21249181 PMCID: PMC3020933 DOI: 10.1371/journal.pgen.1001270] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 12/07/2010] [Indexed: 11/19/2022] Open
Abstract
Expansions of trinucleotide GAA•TTC tracts are associated with the human disease Friedreich's ataxia, and long GAA•TTC tracts elevate genome instability in yeast. We show that tracts of (GAA)230•(TTC)230 stimulate mitotic crossovers in yeast about 10,000-fold relative to a “normal” DNA sequence; (GAA)n•(TTC)n tracts, however, do not significantly elevate meiotic recombination. Most of the mitotic crossovers are associated with a region of non-reciprocal transfer of information (gene conversion). The major class of recombination events stimulated by (GAA)n•(TTC)n tracts is a tract-associated double-strand break (DSB) that occurs in unreplicated chromosomes, likely in G1 of the cell cycle. These findings indicate that (GAA)n•(TTC)n tracts can be a potent source of loss of heterozygosity in yeast. Although meiotic recombination has been much more studied than mitotic recombination, mitotic recombination is a universal property. Meiotic recombination rates are quite variable within the genome, with some chromosomal regions (hotspots) having much higher levels of exchange than other regions (coldspots). For mitotic recombination, although some types of DNA sequences are known to be associated with elevated recombination rates (highly-transcribed genes, inverted repeated sequences), relatively few hotspots have been described. In this report, we show that a 690 base pair region consisting of 230 copies of the (GAA)n•(TTC)n trinucleotide repeat stimulates mitotic crossovers in yeast 10,000-fold more strongly than an “average” yeast sequence. This sequence is a preferred site for chromosome breakage in stationary phase yeast cells. Our findings may be relevant to understanding the expansions of the (GAA)n•(TTC)n trinucleotide repeat tracts that are associated with the human disease Friedreich's ataxia.
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44
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Strawbridge EM, Benson G, Gelfand Y, Benham CJ. The distribution of inverted repeat sequences in the Saccharomyces cerevisiae genome. Curr Genet 2010; 56:321-40. [PMID: 20446088 PMCID: PMC2908449 DOI: 10.1007/s00294-010-0302-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 04/05/2010] [Accepted: 04/08/2010] [Indexed: 02/06/2023]
Abstract
Although a variety of possible functions have been proposed for inverted repeat sequences (IRs), it is not known which of them might occur in vivo. We investigate this question by assessing the distributions and properties of IRs in the Saccharomyces cerevisiae (SC) genome. Using the IRFinder algorithm we detect 100,514 IRs having copy length greater than 6 bp and spacer length less than 77 bp. To assess statistical significance we also determine the IR distributions in two types of randomization of the S. cerevisiae genome. We find that the S. cerevisiae genome is significantly enriched in IRs relative to random. The S. cerevisiae IRs are significantly longer and contain fewer imperfections than those from the randomized genomes, suggesting that processes to lengthen and/or correct errors in IRs may be operative in vivo. The S. cerevisiae IRs are highly clustered in intergenic regions, while their occurrence in coding sequences is consistent with random. Clustering is stronger in the 3' flanks of genes than in their 5' flanks. However, the S. cerevisiae genome is not enriched in those IRs that would extrude cruciforms, suggesting that this is not a common event. Various explanations for these results are considered.
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Affiliation(s)
| | - Gary Benson
- Laboratory for Biocomputing and Informatics, Boston University, Boston, MA USA
| | - Yevgeniy Gelfand
- Laboratory for Biocomputing and Informatics, Boston University, Boston, MA USA
| | - Craig J. Benham
- Department of Mathematics, University of California, Davis, CA 95616 USA
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45
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Cherry T, Longo SL, Tovar-Spinoza Z, Post DE. Second-generation HIF-activated oncolytic adenoviruses with improved replication, oncolytic, and antitumor efficacy. Gene Ther 2010; 17:1430-41. [PMID: 20664541 PMCID: PMC2978277 DOI: 10.1038/gt.2010.100] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There is a need to develop more potent oncolytic adenoviruses that exhibit increased anti-tumor activity in patients. The HYPR-Ads are targeted oncolytic adenoviruses that specifically kill tumor cells which express active hypoxia-inducible factor (HIF). While therapeutically efficacious, the HYPR-Ads exhibited attenuated replication and oncolytic activity. To overcome these deficiencies and improve anti-tumor efficacy, we created new HIF-activated oncolytic Ads, HIF-Ad and HIF-Ad-IL4, which have two key changes: (i) a modified HIF-responsive promoter to regulate the E1A replication gene and (ii) insertion of the E3 gene region. The HIF-Ads demonstrated conditional activation of E1A expression under hypoxia. Importantly, the HIF-Ads exhibit hypoxia-dependent replication, oncolytic, and cellular release activities and potent anti-tumor efficacy, all of which are significantly greater than the HYPR-Ads. Notably, HIF-Ad-IL4 treatment led to regressions in tumor size by 70% and extensive tumor infiltration by leukocytes resulting in an anti-tumor efficacy that is up to 6-fold greater than the HYPR-Ads, HIF-Ad, and wild-type adenovirus treatment. These studies demonstrate that treatment with a HIF-activated oncolytic adenovirus leads to a measurable therapeutic response. The novel design of the HIF-Ads represents a significant improvement compared to first-generation oncolytic Ads and has great potential to increase the efficacy of this cancer therapy.
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Affiliation(s)
- T Cherry
- Department of Neurosurgery, State University of New York (SUNY), Upstate Medical University, Syracuse, NY 13210, USA
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Affiliation(s)
- Francisco Boán
- Departamento de Bioquímica e Bioloxía Molecular, Facultade de Bioloxía-CIBUS, Universidade de Santiago de Compostela, 15782 Santiago, Galicia, Spain
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Kamble VA, Misra HS. The SbcCD complex of Deinococcus radiodurans contributes to radioresistance and DNA strand break repair in vivo and exhibits Mre11–Rad50 type activity in vitro. DNA Repair (Amst) 2010; 9:488-94. [DOI: 10.1016/j.dnarep.2010.01.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 01/14/2010] [Accepted: 01/16/2010] [Indexed: 11/16/2022]
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Noskov VN, Segall-Shapiro TH, Chuang RY. Tandem repeat coupled with endonuclease cleavage (TREC): a seamless modification tool for genome engineering in yeast. Nucleic Acids Res 2010; 38:2570-6. [PMID: 20228123 PMCID: PMC2860121 DOI: 10.1093/nar/gkq099] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The complete synthetic Mycoplasma genitalium genome (∼583 kb) has been assembled and cloned as a circular plasmid in the yeast Saccharomyces cerevisiae. Attempts to engineer the cloned genome by standard genetic methods involving the URA3/5-fluoroorotic acid (5-FOA) counter-selection have shown a high background of 5-FOA resistant clones derived from spontaneous deletions of the bacterial genome maintained in yeast. Here, we report a method that can seamlessly modify the bacterial genome in yeast with high efficiency. This method requires two sequential homologous recombination events. First, the target region is replaced with a mutagenesis cassette that consists of a knock-out CORE (an18-bp I-SceI recognition site, the SCEI gene under the control of the GAL1 promoter, and the URA3 marker) and a DNA fragment homologous to the sequence upstream of the target site. The replacement generates tandem repeat sequences flanking the CORE. Second, galactose induces the expression of I-SceI, which generates a double-strand break (DSB) at the recognition site. This DSB promotes intra-molecular homologous recombination between the repeat sequences, and leads to an excision of the CORE. As a result, a seamless modification is generated. This method can be adapted for a variety of genomic modifications and may provide an important tool to modify and design natural or synthetic genomes propagated in yeast.
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Affiliation(s)
- Vladimir N Noskov
- The J. Craig Venter Institute, 9704 Medical Center Drive, Rockville, MD 20850, USA.
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Delprat A, Negre B, Puig M, Ruiz A. The transposon Galileo generates natural chromosomal inversions in Drosophila by ectopic recombination. PLoS One 2009; 4:e7883. [PMID: 19936241 PMCID: PMC2775673 DOI: 10.1371/journal.pone.0007883] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Accepted: 10/01/2009] [Indexed: 11/25/2022] Open
Abstract
Background Transposable elements (TEs) are responsible for the generation of chromosomal inversions in several groups of organisms. However, in Drosophila and other Dipterans, where inversions are abundant both as intraspecific polymorphisms and interspecific fixed differences, the evidence for a role of TEs is scarce. Previous work revealed that the transposon Galileo was involved in the generation of two polymorphic inversions of Drosophila buzzatii. Methodology/Principal Findings To assess the impact of TEs in Drosophila chromosomal evolution and shed light on the mechanism involved, we isolated and sequenced the two breakpoints of another widespread polymorphic inversion from D. buzzatii, 2z3. In the non inverted chromosome, the 2z3 distal breakpoint was located between genes CG2046 and CG10326 whereas the proximal breakpoint lies between two novel genes that we have named Dlh and Mdp. In the inverted chromosome, the analysis of the breakpoint sequences revealed relatively large insertions (2,870-bp and 4,786-bp long) including two copies of the transposon Galileo (subfamily Newton), one at each breakpoint, plus several other TEs. The two Galileo copies: (i) are inserted in opposite orientation; (ii) present exchanged target site duplications; and (iii) are both chimeric. Conclusions/Significance Our observations provide the best evidence gathered so far for the role of TEs in the generation of Drosophila inversions. In addition, they show unequivocally that ectopic recombination is the causative mechanism. The fact that the three polymorphic D. buzzatii inversions investigated so far were generated by the same transposon family is remarkable and is conceivably due to Galileo's unusual structure and current (or recent) transpositional activity.
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Affiliation(s)
- Alejandra Delprat
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
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Filipenko EA, Deineko EV, Shumnyi VK. Specific features of T-DNA insertion regions in transgenic plants. RUSS J GENET+ 2009. [DOI: 10.1134/s1022795409110040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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