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Gai W, Wang G, Lam WKJ, Yuen LYP, Jiang P, Yu SCY, Leung TY, Lau SL, Lo YMD, Chan KCA. Universal Targeted Haplotyping by Droplet Digital PCR Sequencing and Its Applications in Noninvasive Prenatal Testing and Pharmacogenetics Analysis. Clin Chem 2024; 70:1046-1055. [PMID: 38873917 DOI: 10.1093/clinchem/hvae076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Accepted: 05/01/2024] [Indexed: 06/15/2024]
Abstract
BACKGROUND The analysis of haplotypes of variants is important for pharmacogenomics analysis and noninvasive prenatal testing for monogenic diseases. However, there is a lack of robust methods for targeted haplotyping. METHODS We developed digital PCR haplotype sequencing (dHapSeq) for targeted haplotyping of variants, which is a method that compartmentalizes long DNA molecules into droplets. Within one droplet, 2 target regions are PCR amplified from one template molecule, and their amplicons are fused together. The fused products are then sequenced to determine the phase relationship of the single nucleotide polymorphism (SNP) alleles. The entire haplotype of 10s of SNPs can be deduced after the phase relationship of individual SNPs are determined in a pairwise manner. We applied dHapSeq to noninvasive prenatal testing in 4 families at risk for thalassemia and utilized it to detect NUDT15 diplotypes for predicting drug tolerance in pediatric acute lymphoblastic leukemia (72 cases and 506 controls). RESULTS For SNPs within 40 kb, phase relation can be determined with 100% accuracy. In 7 trio families, the haplotyping results for 97 SNPs spanning 185 kb determined by dHapSeq were concordant with the results deduced from the genotypes of both parents and the fetus. In 4 thalassemia families, a 19.3-kb Southeast Asian deletion was successfully phased with 97 downstream SNPs, enabling noninvasive determination of fetal inheritance using relative haplotype dosage analysis. In the NUDT15 analysis, the variant status and phase of the variants were successfully determined in all cases and controls. CONCLUSIONS The dHapSeq represents a robust and scalable haplotyping approach with numerous clinical and research applications.
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Affiliation(s)
- Wanxia Gai
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - Guangya Wang
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - W K Jacky Lam
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
- State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - Liz Y P Yuen
- Division of Genetic and Genomic Pathology, Department of Pathology, Hong Kong Children's Hospital, Kowloon, Hong Kong SAR, China
| | - Peiyong Jiang
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
- State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - Stephanie C Y Yu
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - Tak Y Leung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - So Ling Lau
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - Y M Dennis Lo
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
- State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
| | - K C Allen Chan
- Centre for Novostics, Hong Kong Science Park, Pak Shek Kok, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
- State Key Laboratory of Translational Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR, China
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Yu Y, Wang H, Tang B, Liang J, Zhang L, Wang H, Bian X, Li YZ, Zhang Y, Zhao GP, Ding X. Reassembly of the Biosynthetic Gene Cluster Enables High Epothilone Yield in Engineered Schlegelella brevitalea. ACS Synth Biol 2020; 9:2009-2022. [PMID: 32603592 DOI: 10.1021/acssynbio.0c00100] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Epothilones, as a new class of microtubule-stabilizing anticancer drugs, exhibit strong bioactivity against taxane-resistant cells and show clinical activity for the treatment of advanced breast cancer. Additionally, they also show great potential for a central nervous system injury and Alzheimer's disease. However, due to the long fermentation period of the original producer and challenges of genetic engineering of nonribosomal peptide/polyketide (NRP/PK) megasynthase genes, the application of epothilones is severely limited. Here, we addressed these problems by reassembling a novel 56-kb epothilone biosynthetic gene cluster, optimizing the promoter of each gene based on RNA-seq profiling, and completing precursor synthetic pathways in engineered Schlegella brevitalea. Furthermore, we debottlenecked the cell autolysis by optimizing culture conditions. Finally, the yield of epothilones in shake flasks was improved to 82 mg/L in six-day fermentation. Overall, we not only constructed epothilone overproducers for further drug development but also provided a rational strategy for high-level NRP/PK compound production.
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Affiliation(s)
- Yucong Yu
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
| | - Huimin Wang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
| | - Biao Tang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
- Institute of Quality and Standard for Agro-products, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, People’s Republic of China
| | - Junheng Liang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
| | - Lin Zhang
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
| | - Hongkuan Wang
- State Key Laboratory of Genetic Engineering and Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, People’s Republic of China
| | - Xiaoying Bian
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People’s Republic of China
| | - Yue-zhong Li
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People’s Republic of China
| | - Youming Zhang
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, People’s Republic of China
| | - Guo-ping Zhao
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
- CAS Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, People’s Republic of China
| | - Xiaoming Ding
- Collaborative Innovation Center for Genetics and Development, State Key Laboratory of Genetic Engineering, Department of Microbiology, School of Life Sciences, Fudan University, Shanghai, 200438, People’s Republic of China
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Wang H, Li Z, Jia R, Yin J, Li A, Xia L, Yin Y, Müller R, Fu J, Stewart AF, Zhang Y. ExoCET: exonuclease in vitro assembly combined with RecET recombination for highly efficient direct DNA cloning from complex genomes. Nucleic Acids Res 2019; 46:e28. [PMID: 29240926 PMCID: PMC5861427 DOI: 10.1093/nar/gkx1249] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/02/2017] [Indexed: 12/29/2022] Open
Abstract
The exponentially increasing volumes of DNA sequence data highlight the need for new DNA cloning methods to explore the new information. Here, we describe ‘ExoCET’ (Exonuclease Combined with RecET recombination) to directly clone any chosen region from bacterial and mammalian genomes with nucleotide precision into operational plasmids. ExoCET combines in vitro exonuclease and annealing with the remarkable capacity of full length RecET homologous recombination (HR) to retrieve specified regions from genomic DNA preparations. Using T4 polymerase (T4pol) as the in vitro exonuclease for ExoCET, we directly cloned large regions (>50 kb) from bacterial and mammalian genomes, including DNA isolated from blood. Employing RecET HR or Cas9 cleavage in vitro, the directly cloned region can be chosen with nucleotide precision to position, for example, a gene into an expression vector without the need for further subcloning. In addition to its utility for bioprospecting in bacterial genomes, ExoCET presents straightforward access to mammalian genomes for various applications such as region-specific DNA sequencing that retains haplotype phasing, the rapid construction of optimal, haplotypic, isogenic targeting constructs or a new way to genotype that presents advantages over Southern blotting or polymerase chain reaction. The direct cloning capacities of ExoCET present new freedoms in recombinant DNA technology.
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Affiliation(s)
- Hailong Wang
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Zhen Li
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Ruonan Jia
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Jia Yin
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Aiying Li
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Liqiu Xia
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, 410081 Changsha, People's Republic of China
| | - Yulong Yin
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China.,State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, 410081 Changsha, People's Republic of China.,Key Laboratory of Subtropical Agro-ecology, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha, Hunan Province 410125, People's Republic of China
| | - Rolf Müller
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China.,Department of Microbial Natural Products, Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI) and Pharmaceutical Biotechnology, Saarland University, Campus C2 3, 66123 Saarbrücken, Germany
| | - Jun Fu
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - A Francis Stewart
- Genomics, Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47-51, 01307 Dresden, Germany
| | - Youming Zhang
- Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
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Revealing complete complex KIR haplotypes phased by long-read sequencing technology. Genes Immun 2017; 18:127-134. [PMID: 28569259 PMCID: PMC5637231 DOI: 10.1038/gene.2017.10] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/26/2017] [Accepted: 03/31/2017] [Indexed: 11/08/2022]
Abstract
The killer cell immunoglobulin-like receptor (KIR) region of human chromosome 19 contains up to 16 genes for natural killer (NK) cell receptors that recognize human leukocyte antigen (HLA)/peptide complexes and other ligands. The KIR proteins fulfill functional roles in infections, pregnancy, autoimmune diseases and transplantation. However, their characterization remains a constant challenge. Not only are the genes highly homologous due to their recent evolution by tandem duplications, but the region is structurally dynamic due to frequent transposon-mediated recombination. A sequencing approach that precisely captures the complexity of KIR haplotypes for functional annotation is desirable. We present a unique approach to haplotype the KIR loci using single-molecule, real-time (SMRT) sequencing. Using this method, we have-for the first time-comprehensively sequenced and phased sixteen KIR haplotypes from eight individuals without imputation. The information revealed four novel haplotype structures, a novel gene-fusion allele, novel and confirmed insertion/deletion events, a homozygous individual, and overall diversity for the structural haplotypes and their alleles. These KIR haplotypes augment our existing knowledge by providing high-quality references, evolutionary informers, and source material for imputation. The haplotype sequences and gene annotations provide alternative loci for the KIR region in the human genome reference GrCh38.p8.
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5
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Suk EK, Schulz S, Mentrup B, Huebsch T, Duitama J, Hoehe MR. A Fosmid Pool-Based Next Generation Sequencing Approach to Haplotype-Resolve Whole Genomes. Methods Mol Biol 2017; 1551:223-269. [PMID: 28138850 DOI: 10.1007/978-1-4939-6750-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Haplotype resolution of human genomes is essential to describe and interpret genetic variation and its impact on biology and disease. Our approach to haplotyping relies on converting genomic DNA into a fosmid library, which represents the entire diploid genome as a collection of haploid DNA clones of ~40 kb in size. These can be partitioned into pools such that the probability that the same pool contains both parental haplotypes is reduced to ~1 %. This is the key principle of this method, allowing entire pools of fosmids to be massively parallel sequenced, yielding haploid sequence output. Here, we present a detailed protocol for fosmid pool-based next generation sequencing to haplotype-resolve whole genomes including the following steps: (1) generation of high molecular weight DNA fragments of ~40 kb in size from genomic DNA; (2) fosmid cloning and partitioning into 96-well plates; (3) barcoded sequencing library preparation from fosmid pools for next generation sequencing; and (4) computational analysis of fosmid sequences and assembly into contiguous haploid sequences.This method can be used in combination with, but also without, whole genome shotgun sequencing to extensively resolve heterozygous SNPs and structural variants within genomic regions, resulting in haploid contigs of several hundred kb up to several Mb. This method has a broad range of applications including population and ancestry genetics, the clinical interpretation of mutations in personal genomes, the analysis of cancer genomes and highly complex disease gene regions such as MHC. Moreover, haplotype-resolved genome sequencing allows description and interpretation of the diploid nature of genome biology, for example through the analysis of haploid gene forms and allele-specific phenomena. Application of this method has enabled the production of most of the molecular haplotype-resolved genomes reported to date.
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Affiliation(s)
- Eun-Kyung Suk
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Sabrina Schulz
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Birgit Mentrup
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Thomas Huebsch
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Jorge Duitama
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
- International Center for Tropical Agriculture (CIAT), Cali, Colombia
| | - Margret R Hoehe
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany.
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Signatures of Crested Ibis MHC Revealed by Recombination Screening and Short-Reads Assembly Strategy. PLoS One 2016; 11:e0168744. [PMID: 27997612 PMCID: PMC5173252 DOI: 10.1371/journal.pone.0168744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 12/06/2016] [Indexed: 02/04/2023] Open
Abstract
Whole-genome shotgun (WGS) sequencing has become a routine method in genome research over the past decade. However, the assembly of highly polymorphic regions in WGS projects remains a challenge, especially for large genomes. Employing BAC library constructing, PCR screening and Sanger sequencing, traditional strategy is laborious and expensive, which hampers research on polymorphic genomic regions. As one of the most highly polymorphic regions, the major histocompatibility complex (MHC) plays a central role in the adaptive immunity of all jawed vertebrates. In this study, we introduced an efficient procedure based on recombination screening and short-reads assembly. With this procedure, we constructed a high quality 488-kb region of crested ibis MHC that consists of 3 superscaffolds and contains 50 genes. Our sequence showed comparable quality (97.29% identity) to traditional Sanger assembly, while the workload was reduced almost 7 times. Comparative study revealed distinctive features of crested ibis by exhibiting the COL11A2-BLA-BLB-BRD2 cluster and presenting both ADPRH and odorant receptor (OR) gene in the MHC region. Furthermore, the conservation of the BF-TAP1-TAP2 structure in crested ibis and other vertebrate lineages is interesting in light of the hypothesis that coevolution of functionally related genes in the primordial MHC is responsible for the appearance of the antigen presentation pathways at the birth of the adaptive immune system.
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RecET direct cloning and Redαβ recombineering of biosynthetic gene clusters, large operons or single genes for heterologous expression. Nat Protoc 2016; 11:1175-90. [PMID: 27254463 DOI: 10.1038/nprot.2016.054] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Full-length RecE and RecT from Rac prophage mediate highly efficient linear-linear homologous recombination that can be used to clone large DNA regions directly from genomic DNA into expression vectors, bypassing library construction and screening. Homologous recombination mediated by Redαβ from lambda phage has been widely used for recombinant DNA engineering. Here we present a protocol for direct cloning and engineering of biosynthetic gene clusters, large operons or single genes from genomic DNA using one Escherichia coli host that harbors both RecET and Redαβ systems. The pipeline uses standardized cassettes for horizontal gene transfer options, as well as vectors with different replication origins configured to minimize recombineering background through the use of selectively replicating templates or CcdB counterselection. These optimized reagents and protocols facilitate fast acquisition of transgenes from genomic DNA preparations, which are ready for heterologous expression within 1 week.
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Abstract
Human genomes are diploid and, for their complete description and interpretation, it is necessary not only to discover the variation they contain but also to arrange it onto chromosomal haplotypes. Although whole-genome sequencing is becoming increasingly routine, nearly all such individual genomes are mostly unresolved with respect to haplotype, particularly for rare alleles, which remain poorly resolved by inferential methods. Here, we review emerging technologies for experimentally resolving (that is, 'phasing') haplotypes across individual whole-genome sequences. We also discuss computational methods relevant to their implementation, metrics for assessing their accuracy and completeness, and the relevance of haplotype information to applications of genome sequencing in research and clinical medicine.
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Reddy TR, Fevat LMS, Munson SE, Stewart AF, Cowley SM. Lambda red mediated gap repair utilizes a novel replicative intermediate in Escherichia coli. PLoS One 2015; 10:e0120681. [PMID: 25803509 PMCID: PMC4372340 DOI: 10.1371/journal.pone.0120681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/05/2015] [Indexed: 11/19/2022] Open
Abstract
The lambda phage Red recombination system can mediate efficient homologous recombination in Escherichia coli, which is the basis of the DNA engineering technique termed recombineering. Red mediated insertion of DNA requires DNA replication, involves a single-stranded DNA intermediate and is more efficient on the lagging strand of the replication fork. Lagging strand recombination has also been postulated to explain the Red mediated repair of gapped plasmids by an Okazaki fragment gap filling model. Here, we demonstrate that gap repair involves a different strand independent mechanism. Gap repair assays examining the strand asymmetry of recombination did not show a lagging strand bias. Directly testing an ssDNA plasmid showed lagging strand recombination is possible but dsDNA plasmids did not employ this mechanism. Insertional recombination combined with gap repair also did not demonstrate preferential lagging strand bias, supporting a different gap repair mechanism. The predominant recombination route involved concerted insertion and subcloning though other routes also operated at lower frequencies. Simultaneous insertion of DNA resulted in modification of both strands and was unaffected by mutations to DNA polymerase I, responsible for Okazaki fragment maturation. The lower efficiency of an alternate Red mediated ends-in recombination pathway and the apparent lack of a Holliday junction intermediate suggested that gap repair does not involve a different Red recombination pathway. Our results may be explained by a novel replicative intermediate in gap repair that does not involve a replication fork. We exploited these observations by developing a new recombineering application based on concerted insertion and gap repair, termed SPI (subcloning plus insertion). SPI selected against empty vector background and selected for correct gap repair recombinants. We used SPI to simultaneously insert up to four different gene cassettes in a single recombineering reaction. Consequently, our findings have important implications for the understanding of E. coli replication and Red recombination.
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Affiliation(s)
- Thimma R. Reddy
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
| | - Léna M. S. Fevat
- Center for Fisheries, Environment and Aquaculture Sciences, Lowestoft, United Kingdom
| | - Sarah E. Munson
- ES Cell Facility, Centre for Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - A. Francis Stewart
- Genomics, BioInnovationsZentrum, Technische Universitaet Dresden, Dresden, Germany
| | - Shaun M. Cowley
- Department of Biochemistry, University of Leicester, Leicester, United Kingdom
- * E-mail:
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Andréasson C, Schick AJ, Pfeiffer SM, Sarov M, Stewart F, Wurst W, Schick JA. Direct cloning of isogenic murine DNA in yeast and relevance of isogenicity for targeting in embryonic stem cells. PLoS One 2013; 8:e74207. [PMID: 24058528 PMCID: PMC3772885 DOI: 10.1371/journal.pone.0074207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 07/30/2013] [Indexed: 12/25/2022] Open
Abstract
Efficient gene targeting in embryonic stem cells requires that modifying DNA sequences are identical to those in the targeted chromosomal locus. Yet, there is a paucity of isogenic genomic clones for human cell lines and PCR amplification cannot be used in many mutation-sensitive applications. Here, we describe a novel method for the direct cloning of genomic DNA into a targeting vector, pRTVIR, using oligonucleotide-directed homologous recombination in yeast. We demonstrate the applicability of the method by constructing functional targeting vectors for mammalian genes Uhrf1 and Gfap. Whereas the isogenic targeting of the gene Uhrf1 showed a substantial increase in targeting efficiency compared to non-isogenic DNA in mouse E14 cells, E14-derived DNA performed better than the isogenic DNA in JM8 cells for both Uhrf1 and Gfap. Analysis of 70 C57BL/6-derived targeting vectors electroporated in JM8 and E14 cell lines in parallel showed a clear dependence on isogenicity for targeting, but for three genes isogenic DNA was found to be inhibitory. In summary, this study provides a straightforward methodological approach for the direct generation of isogenic gene targeting vectors.
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Affiliation(s)
- Claes Andréasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Anna J. Schick
- Physiologisches Institut, Ludwig-Maximilians-Universität, Munich, Germany
| | - Susanne M. Pfeiffer
- Institute of Developmental Genetics, Helmholtz Zentrum Munich, Munich-Neuherberg, Germany
- Technische Universität München, Freising-Weihenstephan, Germany
| | - Mihail Sarov
- The TransgeneOme Project Group, Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Francis Stewart
- Genomics, BioInnovationZentrum, Technische Universität Dresden, Dresden, Germany
| | - Wolfgang Wurst
- Institute of Developmental Genetics, Helmholtz Zentrum Munich, Munich-Neuherberg, Germany
- Technische Universität München, Freising-Weihenstephan, Germany
| | - Joel A. Schick
- Institute of Developmental Genetics, Helmholtz Zentrum Munich, Munich-Neuherberg, Germany
- Technische Universität München, Freising-Weihenstephan, Germany
- * E-mail:
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11
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Shen S, Pyo CW, Vu Q, Wang R, Geraghty DE. The Essential Detail: The Genetics and Genomics of the Primate Immune Response. ILAR J 2013; 54:181-95. [DOI: 10.1093/ilar/ilt043] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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12
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Tyson J, Armour JAL. Determination of haplotypes at structurally complex regions using emulsion haplotype fusion PCR. BMC Genomics 2012; 13:693. [PMID: 23231411 PMCID: PMC3543183 DOI: 10.1186/1471-2164-13-693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 12/07/2012] [Indexed: 12/26/2022] Open
Abstract
Background Genotyping and massively-parallel sequencing projects result in a vast amount of diploid data that is only rarely resolved into its constituent haplotypes. It is nevertheless this phased information that is transmitted from one generation to the next and is most directly associated with biological function and the genetic causes of biological effects. Despite progress made in genome-wide sequencing and phasing algorithms and methods, problems assembling (and reconstructing linear haplotypes in) regions of repetitive DNA and structural variation remain. These dynamic and structurally complex regions are often poorly understood from a sequence point of view. Regions such as these that are highly similar in their sequence tend to be collapsed onto the genome assembly. This is turn means downstream determination of the true sequence haplotype in these regions poses a particular challenge. For structurally complex regions, a more focussed approach to assembling haplotypes may be required. Results In order to investigate reconstruction of spatial information at structurally complex regions, we have used an emulsion haplotype fusion PCR approach to reproducibly link sequences of up to 1kb in length to allow phasing of multiple variants from neighbouring loci, using allele-specific PCR and sequencing to detect the phase. By using emulsion systems linking flanking regions to amplicons within the CNV, this led to the reconstruction of a 59kb haplotype across the DEFA1A3 CNV in HapMap individuals. Conclusion This study has demonstrated a novel use for emulsion haplotype fusion PCR in addressing the issue of reconstructing structural haplotypes at multiallelic copy variable regions, using the DEFA1A3 locus as an example.
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Affiliation(s)
- Jess Tyson
- School of Biology, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
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Sarov M, Murray JI, Schanze K, Pozniakovski A, Niu W, Angermann K, Hasse S, Rupprecht M, Vinis E, Tinney M, Preston E, Zinke A, Enst S, Teichgraber T, Janette J, Reis K, Janosch S, Schloissnig S, Ejsmont RK, Slightam C, Xu X, Kim SK, Reinke V, Stewart AF, Snyder M, Waterston RH, Hyman AA. A genome-scale resource for in vivo tag-based protein function exploration in C. elegans. Cell 2012; 150:855-66. [PMID: 22901814 DOI: 10.1016/j.cell.2012.08.001] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 03/22/2012] [Accepted: 08/01/2012] [Indexed: 12/21/2022]
Abstract
Understanding the in vivo dynamics of protein localization and their physical interactions is important for many problems in biology. To enable systematic protein function interrogation in a multicellular context, we built a genome-scale transgenic platform for in vivo expression of fluorescent- and affinity-tagged proteins in Caenorhabditis elegans under endogenous cis regulatory control. The platform combines computer-assisted transgene design, massively parallel DNA engineering, and next-generation sequencing to generate a resource of 14,637 genomic DNA transgenes, which covers 73% of the proteome. The multipurpose tag used allows any protein of interest to be localized in vivo or affinity purified using standard tag-based assays. We illustrate the utility of the resource by systematic chromatin immunopurification and automated 4D imaging, which produced detailed DNA binding and cell/tissue distribution maps for key transcription factor proteins.
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Affiliation(s)
- Mihail Sarov
- TransgeneOmics Unit, Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
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