1
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Li Y, Pinones M, Breeland A, Jiang P. Single-round QuikChange PCR for engineering multiple site-directed mutations in plasmid DNA. Anal Biochem 2024; 694:115621. [PMID: 39019205 DOI: 10.1016/j.ab.2024.115621] [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] [Received: 04/16/2024] [Revised: 06/08/2024] [Accepted: 07/14/2024] [Indexed: 07/19/2024]
Abstract
Mutational study is a cornerstone methodology in biochemistry and genetics, and many mutagenesis strategies have been invented to promote the efficiency of gene engineering. In this study, we developed a simple and timesaving approach to integrate simultaneous mutagenesis at discrete sites. By using plasmid as a template and compatible oligonucleotide primers per the QuikChange strategy, our method was able to introduce multiple nucleotide insertions, deletions and replacements in one round of polymerase chain reaction. The longest insertion and deletion were achieved with 28 bp and 16 bp mismatch respectively. For minor nucleotide replacements (mismatch no more than 4 bp), mutations were achieved at up to 4 discrete locations. Usually, a successful clone with all desired mutations was found by screening 5 colonies. Clones with a subset of mutations may be stocked into the library of mutants or used as templates in the next rounds of mutagenic PCR to accomplish the entire construction project. This method can be applied to build up a combinatory library of mutants through saturation mutagenesis at multiple sites. It is promising to facilitate the research of protein biochemistry, forward genetics and synthetic biology.
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Affiliation(s)
- Yunxiang Li
- Division of Chemistry and Biochemistry, Texas Woman's University, Denton, TX, 76204, USA.
| | - Mileina Pinones
- Division of Chemistry and Biochemistry, Texas Woman's University, Denton, TX, 76204, USA
| | - Alexis Breeland
- Division of Biology, Texas Woman's University, Denton, TX, 76204, USA
| | - Peilin Jiang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409, USA
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2
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OverFlap PCR: A reliable approach for generating plasmid DNA libraries containing random sequences without a template bias. PLoS One 2022; 17:e0262968. [PMID: 35939421 PMCID: PMC9359533 DOI: 10.1371/journal.pone.0262968] [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: 01/03/2022] [Accepted: 07/17/2022] [Indexed: 11/19/2022] Open
Abstract
Over the decades, practical biotechnology researchers have aimed to improve naturally occurring proteins and create novel ones. It is widely recognized that coupling protein sequence randomization with various effect screening methodologies is one of the most powerful techniques for quickly, efficiently, and purposefully acquiring these desired improvements. Over the years, considerable advancements have been made in this field. However, developing PCR-based or template-guided methodologies has been hampered by resultant template sequence biases. Here, we present a novel whole plasmid amplification-based approach, which we named OverFlap PCR, for randomizing virtually any region of plasmid DNA without introducing a template sequence bias.
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3
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Körfer G, Besirlioglu V, Davari MD, Martinez R, Vojcic L, Schwaneberg U. Combinatorial InVitroFlow-assisted Mutagenesis (CombIMut) yields a 41-fold improved CelA2 cellulase. Biotechnol Bioeng 2022; 119:2076-2087. [PMID: 35451061 DOI: 10.1002/bit.28110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 03/21/2022] [Accepted: 04/03/2022] [Indexed: 11/11/2022]
Abstract
The combination of diversity generation methods and ultrahigh-throughput screening (uHTS) technologies is key to efficiently explore nature's sequence space and elucidate structure-function relationships of enzymes. Beneficial substitutions often cluster in a few regions and simultaneous amino acid substitutions at multiple positions (e.g., by OmniChange) will likely lead to further improved enzyme variants. An extensive screening effort is required to identify such variants, as the simultaneous randomization of four codons can easily yield over 105 potential enzyme variants. The combination of flow cytometer-based uHTS with cell-free compartmentalization technology using (w/o/w) double emulsions (InVitroFlow), provides analysis capabilities of up to 107 events per hour, thus enabling efficient screening. InVitroFlow is an elegant solution since diversity loss through a transformation of host cells is omitted and emulsion compartments provide a genotype-phenotype linkage through a fluorescence readout. In this work, a multi-site saturation mutagenesis (mSSM) and an OmniChange library with four simultaneously saturated positions in the active site of CelA2 cellulase were screened using InVitroFlow. Screening of over 36 million events, yielded a significantly improved cellulase variant CelA2-M3 (H288F/H524Q) with an 8-fold increase in specific activity compared to the parent CelA2-H288F (83.9 U/mg) and a 41-fold increased specific activity (674.5 U/mg) compared to wildtype CelA2 (16.6 U/mg) for the substrate 4-MUC (4-methylumbelliferyl-β D-cellobioside). This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Georgette Körfer
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany
| | - Volkan Besirlioglu
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany
| | - Mehdi D Davari
- Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120, Halle, Germany
| | - Ronny Martinez
- Universidad de La Serena, Departamento de Ingeniería en Alimentos, Av. Raúl Bitrán 1305, 1720010, La Serena, Chile
| | - Ljubica Vojcic
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany.,Current address: Codexis Inc., 200 Penobscot Drive, Redwood City, CA, 94063, USA
| | - Ulrich Schwaneberg
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany.,DWI an der RWTH Aachen e.V, Forckenbeckstraße 50, 52056, Aachen, Germany
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4
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SpeedyGenesXL: an Automated, High-Throughput Platform for the Preparation of Bespoke Ultralarge Variant Libraries for Directed Evolution. Methods Mol Biol 2022; 2461:67-83. [PMID: 35727444 DOI: 10.1007/978-1-0716-2152-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Directed evolution of proteins is a highly effective strategy for tailoring biocatalysts to a particular application, and is capable of engineering improvements such as kcat, thermostability and organic solvent tolerance. It is recognized that large and systematic libraries are required to navigate a protein's vast and rugged sequence landscape effectively, yet their preparation is nontrivial and commercial libraries are extremely costly. To address this, we have developed SpeedyGenesXL, an automated, high-throughput platform for the production of wild-type genes, Boolean OR, combinatorial, or combinatorial-OR-type libraries based on the SpeedyGenes methodology. Together this offers a flexible platform for library synthesis, capable of generating many different bespoke, diverse libraries simultaneously.
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5
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Wang Y, Xue P, Cao M, Yu T, Lane ST, Zhao H. Directed Evolution: Methodologies and Applications. Chem Rev 2021; 121:12384-12444. [PMID: 34297541 DOI: 10.1021/acs.chemrev.1c00260] [Citation(s) in RCA: 184] [Impact Index Per Article: 61.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Directed evolution aims to expedite the natural evolution process of biological molecules and systems in a test tube through iterative rounds of gene diversifications and library screening/selection. It has become one of the most powerful and widespread tools for engineering improved or novel functions in proteins, metabolic pathways, and even whole genomes. This review describes the commonly used gene diversification strategies, screening/selection methods, and recently developed continuous evolution strategies for directed evolution. Moreover, we highlight some representative applications of directed evolution in engineering nucleic acids, proteins, pathways, genetic circuits, viruses, and whole cells. Finally, we discuss the challenges and future perspectives in directed evolution.
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Affiliation(s)
- Yajie Wang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Pu Xue
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Mingfeng Cao
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tianhao Yu
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Stephan T Lane
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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6
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Meinke G, Dalda N, Brigham BS, Bohm A. Synthesis of libraries and multi-site mutagenesis using a PCR-derived, dU-containing template. Synth Biol (Oxf) 2021; 6:ysaa030. [PMID: 34239985 PMCID: PMC8260824 DOI: 10.1093/synbio/ysaa030] [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: 08/14/2020] [Revised: 11/20/2020] [Accepted: 12/14/2020] [Indexed: 12/03/2022] Open
Abstract
Directed DNA libraries are useful because they focus genetic diversity in the most important regions within a sequence. Ideally, all sequences in such libraries should appear with the same frequency and there should be no significant background from the starting sequence. These properties maximize the number of different sequences that can be screened. Described herein is a method termed SLUPT (Synthesis of Libraries via a dU-containing PCR-derived Template) for generating highly targeted DNA libraries and/or multi-site mutations wherein the altered bases may be widely distributed within a target sequence. This method is highly efficient and modular. Moreover, multiple distinct sites, each with one or more base changes, can be altered in a single reaction. There is very low background from the starting sequence, and SLUPT libraries have similar representation of each base at the positions selected for variation. The SLUPT method utilizes a single-stranded dU-containing DNA template that is made by polymerase chain reaction (PCR). Synthesis of the template in this way is significantly easier than has been described earlier. A series of oligonucleotide primers that are homologous to the template and encode the desired genetic diversity are extended and ligated in a single reaction to form the mutated product sequence or library. After selective inactivation of the template, only the product library is amplified. There are no restrictions on the spacing of the mutagenic primers except that they cannot overlap.
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Affiliation(s)
- Gretchen Meinke
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Nahide Dalda
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Benjamin S Brigham
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Andrew Bohm
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA 02111, USA
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7
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Cozens C, Pinheiro VB. Darwin Assembly: fast, efficient, multi-site bespoke mutagenesis. Nucleic Acids Res 2019; 46:e51. [PMID: 29409059 PMCID: PMC5934624 DOI: 10.1093/nar/gky067] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/24/2018] [Indexed: 12/15/2022] Open
Abstract
Engineering proteins for designer functions and biotechnological applications almost invariably requires (or at least benefits from) multiple mutations to non-contiguous residues. Several methods for multiple site-directed mutagenesis exist, but there remains a need for fast and simple methods to efficiently introduce such mutations – particularly for generating large, high quality libraries for directed evolution. Here, we present Darwin Assembly, which can deliver high quality libraries of >108 transformants, targeting multiple (>10) distal sites with minimal wild-type contamination (<0.25% of total population) and which takes a single working day from purified plasmid to library transformation. We demonstrate its efficacy with whole gene codon reassignment of chloramphenicol acetyl transferase, mutating 19 codons in a single reaction in KOD DNA polymerase and generating high quality, multiple-site libraries in T7 RNA polymerase and Tgo DNA polymerase. Darwin Assembly uses commercially available enzymes, can be readily automated, and offers a cost-effective route to highly complex and customizable library generation.
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Affiliation(s)
| | - Vitor B Pinheiro
- University College London, Gower Street, London WC1E 6BT, UK.,Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street WC1E 7HX, UK
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8
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Identification of Thermus aquaticus DNA polymerase variants with increased mismatch discrimination and reverse transcriptase activity from a smart enzyme mutant library. Sci Rep 2019; 9:590. [PMID: 30679705 PMCID: PMC6345897 DOI: 10.1038/s41598-018-37233-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/02/2018] [Indexed: 12/13/2022] Open
Abstract
DNA polymerases the key enzymes for several biotechnological applications. Obviously, nature has not evolved these enzymes to be compatible with applications in biotechnology. Thus, engineering of a natural scaffold of DNA polymerases may lead to enzymes improved for several applications. Here, we investigated a two-step approach for the design and construction of a combinatorial library of mutants of KlenTaq DNA polymerase. First, we selected amino acid sites for saturation mutagenesis that interact with the primer/template strands or are evolutionarily conserved. From this library, we identified mutations that little interfere with DNA polymerase activity. Next, these functionally active mutants were combined randomly to construct a second library with enriched sequence diversity. We reasoned that the combination of mutants that have minuscule effect on enzyme activity and thermostability, will result in entities that have an increased mutation load but still retain activity. Besides activity and thermostability, we screened the library for entities with two distinct properties. Indeed, we identified two different KlenTaq DNA polymerase variants that either exhibit increased mismatch extension discrimination or increased reverse transcription PCR activity, respectively.
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9
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Multiplexed assays of variant effects contribute to a growing genotype-phenotype atlas. Hum Genet 2018; 137:665-678. [PMID: 30073413 PMCID: PMC6153521 DOI: 10.1007/s00439-018-1916-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 07/21/2018] [Indexed: 12/12/2022]
Abstract
Given the constantly improving cost and speed of genome sequencing, it is reasonable to expect that personal genomes will soon be known for many millions of humans. This stands in stark contrast with our limited ability to interpret the sequence variants which we find. Although it is, perhaps, easiest to interpret variants in coding regions, knowledge of functional impact is unknown for the vast majority of missense variants. While many computational approaches can predict the impact of coding variants, they are given a little weight in the current guidelines for interpreting clinical variants. Laboratory assays produce comparatively more trustworthy results, but until recently did not scale to the space of all possible mutations. The development of deep mutational scanning and other multiplexed assays of variant effect has now brought feasibility of this endeavour within view. Here, we review progress in this field over the last decade, break down the different approaches into their components, and compare methodological differences.
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10
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Abstract
Directed evolution (DE) is a powerful tool for optimizing an enzyme's properties toward a particular objective, such as broader substrate scope, greater thermostability, or increased kcat. A successful DE project requires the generation of genetic diversity and subsequent screening or selection to identify variants with improved fitness. In contrast to random methods (error-prone PCR or DNA shuffling), site-directed mutagenesis enables the rational design of variant libraries and provides control over the nature and frequency of the encoded mutations. Knowledge of protein structure, dynamics, enzyme mechanisms, and natural evolution demonstrates that multiple (combinatorial) mutations are required to discover the most improved variants. To this end, we describe an experimentally straightforward and low-cost method for the preparation of combinatorial variant libraries. Our approach employs a two-step PCR protocol, first producing mutagenic megaprimers, which can then be combined in a "mix-and-match" fashion to generate diverse sets of combinatorial variant libraries both quickly and accurately.
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11
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Kschonsak YT, Hoffmann I. Activated Ezrin controls MISP levels to ensure correct NuMA polarization and spindle orientation. J Cell Sci 2018; 131:jcs.214544. [DOI: 10.1242/jcs.214544] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/11/2018] [Indexed: 12/11/2022] Open
Abstract
Correct spindle orientation is achieved through signaling pathways that provide a molecular link between the cell cortex and spindle microtubules in an F-actin dependent manner. A conserved cortical protein complex, composed of LGN, NuMA, dynein-dynactin, plays a key role in establishing proper spindle orientation. It has also been shown that the actin-binding protein MISP and the ERM family, that are activated by LOK/SLK in mitosis, regulate spindle orientation. Here, we report that MISP functions between the ERM family member Ezrin and NuMA to allow optimal spindle positioning. We show that MISP directly interacts with Ezrin and that SLK/LOK-activated Ezrin ensures appropriate cortical MISP levels in mitosis by competing with MISP for actin-binding sites at the cell cortex. Furthermore, we found that regulation of proper cortical MISP levels by preventing its excessive accumulation is essential for crescent-like polarized NuMA localization at the cortex and as a consequence for highly dynamic astral microtubules. Our results uncover how appropriate MISP levels at the cortex are required for proper NuMA polarization and therefore an optimal placement of the mitotic spindle within the cell.
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Affiliation(s)
- Yvonne T. Kschonsak
- Cell Cycle Control and Carcinogenesis, F045, German Cancer Research Center, DKFZ, 69120 Heidelberg, Germany
- University of Heidelberg, F045, German Cancer Research Center, DKFZ, 69120 Heidelberg, Germany
| | - Ingrid Hoffmann
- Cell Cycle Control and Carcinogenesis, F045, German Cancer Research Center, DKFZ, 69120 Heidelberg, Germany
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12
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Kang Z, Ding W, Jin P, Du G, Chen J. Combinatorial Evolution of DNA with RECODE. Methods Mol Biol 2018; 1772:205-212. [PMID: 29754230 DOI: 10.1007/978-1-4939-7795-6_11] [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: 06/08/2023]
Abstract
In past decades, DNA engineering protocols have led to the rapid development of synthetic biology. To engineer the natural proteins, many directed evolution methods based on molecular biology have been presented for generating genetic diversity or obtaining specific properties. Here, we provide a simple (PCR operation), efficient (larger amount of products), and powerful (multiple point mutations, deletions, insertions, and combinatorial multipoint mutagenesis) RECODE method, which is capable of reediting the target DNA flexibly to restructure regulatory regions and remodel enzymes by using the combined function of the thermostable DNA polymerase and DNA ligase in one pot. RECODE is expected to be an applicable choice to create diverse mutant libraries for rapid evolution and optimization of enzymes and synthetic pathways.
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Affiliation(s)
- Zhen Kang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China.
- Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China.
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China.
| | - Wenwen Ding
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Peng Jin
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Guocheng Du
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China
| | - Jian Chen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China
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13
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Weile J, Sun S, Cote AG, Knapp J, Verby M, Mellor JC, Wu Y, Pons C, Wong C, van Lieshout N, Yang F, Tasan M, Tan G, Yang S, Fowler DM, Nussbaum R, Bloom JD, Vidal M, Hill DE, Aloy P, Roth FP. A framework for exhaustively mapping functional missense variants. Mol Syst Biol 2017; 13:957. [PMID: 29269382 PMCID: PMC5740498 DOI: 10.15252/msb.20177908] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Although we now routinely sequence human genomes, we can confidently identify only a fraction of the sequence variants that have a functional impact. Here, we developed a deep mutational scanning framework that produces exhaustive maps for human missense variants by combining random codon mutagenesis and multiplexed functional variation assays with computational imputation and refinement. We applied this framework to four proteins corresponding to six human genes: UBE2I (encoding SUMO E2 conjugase), SUMO1 (small ubiquitin‐like modifier), TPK1 (thiamin pyrophosphokinase), and CALM1/2/3 (three genes encoding the protein calmodulin). The resulting maps recapitulate known protein features and confidently identify pathogenic variation. Assays potentially amenable to deep mutational scanning are already available for 57% of human disease genes, suggesting that DMS could ultimately map functional variation for all human disease genes.
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Affiliation(s)
- Jochen Weile
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Song Sun
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada.,Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Atina G Cote
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Jennifer Knapp
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Marta Verby
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Joseph C Mellor
- The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,SeqWell Inc, Boston, MA, USA
| | - Yingzhou Wu
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Carles Pons
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute for Science and Technology, Barcelona, Catalonia, Spain
| | - Cassandra Wong
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | | | - Fan Yang
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Murat Tasan
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada
| | - Guihong Tan
- The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Shan Yang
- Invitae Corp., San Francisco, CA, USA
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | | | - Marc Vidal
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - David E Hill
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, MA, USA
| | - Patrick Aloy
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute for Science and Technology, Barcelona, Catalonia, Spain.,Institució Catalana de Recerca I Estudis Avançats (ICREA), Barcelona, Catalonia, Spain
| | - Frederick P Roth
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada .,The Donnelly Centre, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Department of Computer Science, University of Toronto, Toronto, ON, Canada.,Canadian Institute for Advanced Research, Toronto, ON, Canada
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14
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Bratulic S, Badran AH. Modern methods for laboratory diversification of biomolecules. Curr Opin Chem Biol 2017; 41:50-60. [PMID: 29096324 PMCID: PMC6062405 DOI: 10.1016/j.cbpa.2017.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 10/03/2017] [Accepted: 10/08/2017] [Indexed: 11/29/2022]
Abstract
Genetic variation fuels Darwinian evolution, yet spontaneous mutation rates are maintained at low levels to ensure cellular viability. Low mutation rates preclude the exhaustive exploration of sequence space for protein evolution and genome engineering applications, prompting scientists to develop methods for efficient and targeted diversification of nucleic acid sequences. Directed evolution of biomolecules relies upon the generation of unbiased genetic diversity to discover variants with desirable properties, whereas genome-engineering applications require selective modifications on a genomic scale with minimal off-targets. Here, we review the current toolkit of mutagenesis strategies employed in directed evolution and genome engineering. These state-of-the-art methods enable facile modifications and improvements of single genes, multicomponent pathways, and whole genomes for basic and applied research, while simultaneously paving the way for genome editing therapeutic interventions.
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Affiliation(s)
- Sinisa Bratulic
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Ahmed H Badran
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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15
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Chung DH, Potter SC, Tanomrat AC, Ravikumar KM, Toney MD. Site-directed mutant libraries for isolating minimal mutations yielding functional changes. Protein Eng Des Sel 2017; 30:347-357. [DOI: 10.1093/protein/gzx013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 02/14/2017] [Indexed: 11/12/2022] Open
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16
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Simple-MSSM: a simple and efficient method for simultaneous multi-site saturation mutagenesis. Biotechnol Lett 2017; 39:567-575. [PMID: 28044225 DOI: 10.1007/s10529-016-2278-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/20/2016] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To develop a practically simple and robust multi-site saturation mutagenesis (MSSM) method that enables simultaneously recombination of amino acid positions for focused mutant library generation. RESULTS A general restriction enzyme-free and ligase-free MSSM method (Simple-MSSM) based on prolonged overlap extension PCR (POE-PCR) and Simple Cloning techniques. As a proof of principle of Simple-MSSM, the gene of eGFP (enhanced green fluorescent protein) was used as a template gene for simultaneous mutagenesis of five codons. Forty-eight randomly selected clones were sequenced. Sequencing revealed that all the 48 clones showed at least one mutant codon (mutation efficiency = 100%), and 46 out of the 48 clones had mutations at all the five codons. The obtained diversities at these five codons are 27, 24, 26, 26 and 22, respectively, which correspond to 84, 75, 81, 81, 69% of the theoretical diversity offered by NNK-degeneration (32 codons; NNK, K = T or G). CONCLUSION The enzyme-free Simple-MSSM method can simultaneously and efficiently saturate five codons within one day, and therefore avoid missing interactions between residues in interacting amino acid networks.
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17
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Xu JZ, Zhang WG. Strategies used for genetically modifying bacterial genome: site-directed mutagenesis, gene inactivation, and gene over-expression. J Zhejiang Univ Sci B 2016; 17:83-99. [PMID: 26834010 DOI: 10.1631/jzus.b1500187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators.
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Affiliation(s)
- Jian-zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Wei-guo Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
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18
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Jin P, Kang Z, Zhang J, Zhang L, Du G, Chen J. Combinatorial Evolution of Enzymes and Synthetic Pathways Using One-Step PCR. ACS Synth Biol 2016; 5:259-68. [PMID: 26751617 DOI: 10.1021/acssynbio.5b00240] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA engineering is the fundamental motive driving the rapid development of modern biotechnology. Here, we present a versatile evolution method termed "rapidly efficient combinatorial oligonucleotides for directed evolution" (RECODE) for rapidly introducing multiple combinatorial mutations to the target DNA by combined action of a thermostable high-fidelity DNA polymerase and a thermostable DNA Ligase in one reaction system. By applying this method, we rapidly constructed a variant library of the rpoS promoters (with activity of 8-460%), generated a novel heparinase from the highly specific leech hyaluronidase (with more than 30 mutant residues) and optimized the heme biosynthetic pathway by combinatorial evolution of regulatory elements and pathway enzymes (2500 ± 120 mg L(-1) with 20-fold increase). The simple RECODE method enabled researchers the unparalleled ability to efficiently create diverse mutant libraries for rapid evolution and optimization of enzymes and synthetic pathways.
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Affiliation(s)
- Peng Jin
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Zhen Kang
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
- The
Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry
of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Junli Zhang
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Linpei Zhang
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Guocheng Du
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
- The
Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry
of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jian Chen
- The
Key Laboratory of Industrial Biotechnology, Ministry of Education,
School of Biotechnology, Jiangnan University, Wuxi 214122, China
- Synergetic
Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China
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Ren C, Xu K, Liu Z, Shen J, Han F, Chen Z, Zhang Z. Dual-reporter surrogate systems for efficient enrichment of genetically modified cells. Cell Mol Life Sci 2015; 72:2763-72. [PMID: 25725802 PMCID: PMC11113981 DOI: 10.1007/s00018-015-1874-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/01/2015] [Accepted: 02/24/2015] [Indexed: 12/21/2022]
Abstract
Isolation of genetically modified cells generated by designed nucleases are challenging, since they are often phenotypically indistinguishable from their parental cells. To efficiently enrich genetically modified cells, we developed two dual-reporter surrogate systems, namely NHEJ-RPG and SSA-RPG based on NHEJ and SSA repair mechanisms, respectively. Repair and enrichment efficiencies of these two systems were compared using different nucleases. In both CRISPR-Cas9- and ZFNs-induced DSB repair studies, we found that the efficiency and sensitivity of the SSA-RPG reporter with direct repeat length more than 200 bp were much higher than the NHEJ-RPG reporter. By utilizing the SSA-RPG reporter, we achieved the enrichment for indels in several endogenous loci with 6.3- to 34.8-fold of non-selected cells. Thus, the highly sensitive SSA-RPG reporter can be used for activity validation of designed nucleases and efficient enrichment of genetically modified cells. Besides, our systems offer alternative enrichment choices either by puromycin selection or FACS.
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Affiliation(s)
- Chonghua Ren
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Kun Xu
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Zhongtian Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Juncen Shen
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Furong Han
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Zhilong Chen
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Zhiying Zhang
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 Shaanxi China
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20
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Nagasawa K, Meguro M, Sato K, Tanizaki Y, Nogawa-Kosaka N, Kato T. The influence of artificially introduced N-glycosylation sites on the in vitro activity of Xenopus laevis erythropoietin. PLoS One 2015; 10:e0124676. [PMID: 25898205 PMCID: PMC4405594 DOI: 10.1371/journal.pone.0124676] [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: 10/22/2014] [Accepted: 03/16/2015] [Indexed: 11/18/2022] Open
Abstract
Erythropoietin (EPO), the primary regulator of erythropoiesis, is a heavily glycosylated protein found in humans and several other mammals. Intriguingly, we have previously found that EPO in Xenopus laevis (xlEPO) has no N-glycosylation sites, and cross-reacts with the human EPO (huEPO) receptor despite low homology with huEPO. In this study, we introduced N-glycosylation sites into wild-type xlEPO at the positions homologous to those in huEPO, and tested whether the glycosylated mutein retained its biological activity. Seven xlEPO muteins, containing 1–3 additional N-linked carbohydrates at positions 24, 38, and/or 83, were expressed in COS-1 cells. The muteins exhibited lower secretion efficiency, higher hydrophilicity, and stronger acidic properties than the wild type. All muteins stimulated the proliferation of both cell lines, xlEPO receptor-expressing xlEPOR-FDC/P2 cells and huEPO receptor-expressing UT-7/EPO cells, in a dose-dependent manner. Thus, the muteins retained their in vitro biological activities. The maximum effect on xlEPOR-FDC/P2 proliferation was decreased by the addition of N-linked carbohydrates, but that on UT-7/EPO proliferation was not changed, indicating that the muteins act as partial agonists to the xlEPO receptor, and near-full agonists to the huEPO receptor. Hence, the EPO-EPOR binding site in X. laevis locates the distal region of artificially introduced three N-glycosylation sites, demonstrating that the vital conformation to exert biological activity is conserved between humans and X. laevis, despite the low similarity in primary structures of EPO and EPOR.
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Affiliation(s)
- Kazumichi Nagasawa
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
| | - Mizue Meguro
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
| | - Kei Sato
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
| | - Yuta Tanizaki
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
- Department of Biology, School of Education, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
| | - Nami Nogawa-Kosaka
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
| | - Takashi Kato
- Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
- Department of Biology, School of Education, Waseda University, Center for Advanced Biomedical Science, TWIns building, 2–2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162–8480, Japan
- * E-mail:
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21
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Currin A, Swainston N, Day PJ, Kell DB. Synthetic biology for the directed evolution of protein biocatalysts: navigating sequence space intelligently. Chem Soc Rev 2015; 44:1172-239. [PMID: 25503938 PMCID: PMC4349129 DOI: 10.1039/c4cs00351a] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Indexed: 12/21/2022]
Abstract
The amino acid sequence of a protein affects both its structure and its function. Thus, the ability to modify the sequence, and hence the structure and activity, of individual proteins in a systematic way, opens up many opportunities, both scientifically and (as we focus on here) for exploitation in biocatalysis. Modern methods of synthetic biology, whereby increasingly large sequences of DNA can be synthesised de novo, allow an unprecedented ability to engineer proteins with novel functions. However, the number of possible proteins is far too large to test individually, so we need means for navigating the 'search space' of possible protein sequences efficiently and reliably in order to find desirable activities and other properties. Enzymologists distinguish binding (Kd) and catalytic (kcat) steps. In a similar way, judicious strategies have blended design (for binding, specificity and active site modelling) with the more empirical methods of classical directed evolution (DE) for improving kcat (where natural evolution rarely seeks the highest values), especially with regard to residues distant from the active site and where the functional linkages underpinning enzyme dynamics are both unknown and hard to predict. Epistasis (where the 'best' amino acid at one site depends on that or those at others) is a notable feature of directed evolution. The aim of this review is to highlight some of the approaches that are being developed to allow us to use directed evolution to improve enzyme properties, often dramatically. We note that directed evolution differs in a number of ways from natural evolution, including in particular the available mechanisms and the likely selection pressures. Thus, we stress the opportunities afforded by techniques that enable one to map sequence to (structure and) activity in silico, as an effective means of modelling and exploring protein landscapes. Because known landscapes may be assessed and reasoned about as a whole, simultaneously, this offers opportunities for protein improvement not readily available to natural evolution on rapid timescales. Intelligent landscape navigation, informed by sequence-activity relationships and coupled to the emerging methods of synthetic biology, offers scope for the development of novel biocatalysts that are both highly active and robust.
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Affiliation(s)
- Andrew Currin
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- School of Chemistry , The University of Manchester , Manchester M13 9PL , UK
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
| | - Neil Swainston
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
- School of Computer Science , The University of Manchester , Manchester M13 9PL , UK
| | - Philip J. Day
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
- Faculty of Medical and Human Sciences , The University of Manchester , Manchester M13 9PT , UK
| | - Douglas B. Kell
- Manchester Institute of Biotechnology , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK . ; http://dbkgroup.org/; @dbkell ; Tel: +44 (0)161 306 4492
- School of Chemistry , The University of Manchester , Manchester M13 9PL , UK
- Centre for Synthetic Biology of Fine and Speciality Chemicals (SYNBIOCHEM) , The University of Manchester , 131, Princess St , Manchester M1 7DN , UK
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22
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Ruff AJ, Dennig A, Schwaneberg U. To get what we aim for - progress in diversity generation methods. FEBS J 2013; 280:2961-78. [DOI: 10.1111/febs.12325] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 01/06/2023]
Affiliation(s)
- Anna J. Ruff
- Lehrstuhl für Biotechnologie; RWTH Aachen University; Germany
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23
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Parallel assembly for multiple site-directed mutagenesis of plasmids. Anal Biochem 2012; 430:65-7. [PMID: 22885236 DOI: 10.1016/j.ab.2012.07.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/25/2012] [Accepted: 07/27/2012] [Indexed: 11/24/2022]
Abstract
A parallel assembly method for multiple site-directed mutagenesis of plasmids was developed here based on Golden Gate cloning. It takes advantage of type IIs restriction enzymes and T4 DNA ligase to assemble multiple DNA fragments into a plasmid by a defined order. This method can accommodate multiple plasmid mutagenesis at any desired position with all three sequence modification types (substitution, deletion, and insertion) simultaneously. Furthermore, it can be used to create otherwise difficult-to-make mutants-larger deletions and insertions and mutagenesis on larger plasmids. The processes of mutagenesis can be completed quickly by a single restriction-ligation reaction.
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24
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Siloto RM, Weselake RJ. Site saturation mutagenesis: Methods and applications in protein engineering. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2012. [DOI: 10.1016/j.bcab.2012.03.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Liang X, Peng L, Li K, Peterson T, Katzen F. A method for multi-site-directed mutagenesis based on homologous recombination. Anal Biochem 2012; 427:99-101. [PMID: 22579595 DOI: 10.1016/j.ab.2012.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 05/01/2012] [Accepted: 05/02/2012] [Indexed: 10/28/2022]
Abstract
We have developed an efficient method for the simultaneous introduction of up to three mutations in a plasmid DNA via homologous recombination. The strategy is compatible with a variety of mutations, including degenerate codons in plasmids of different sizes. In contrast to other methodologies, this approach employs the same set of reagents for both single- and multi-site mutagenesis assays, minimizes the required protocol steps, and exhibits remarkably high mutagenesis efficiencies.
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26
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Bok JW, Keller NP. Fast and easy method for construction of plasmid vectors using modified quick-change mutagenesis. Methods Mol Biol 2012; 944:163-74. [PMID: 23065615 PMCID: PMC3692276 DOI: 10.1007/978-1-62703-122-6_11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Plasmid vector construction is an essential step for molecular microbiology yet often a time-consuming process. Manipulation of the fungal genome to express genes to activate secondary metabolite production often requires creation of plasmid constructs in a reiterative fashion. Here we introduce a modified Quick-change site-directed mutagenesis method that allows for rapid and accurate construction of fungal transformation vectors.
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27
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Dennig A, Shivange AV, Marienhagen J, Schwaneberg U. OmniChange: the sequence independent method for simultaneous site-saturation of five codons. PLoS One 2011; 6:e26222. [PMID: 22039444 PMCID: PMC3198389 DOI: 10.1371/journal.pone.0026222] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/22/2011] [Indexed: 12/20/2022] Open
Abstract
Focused mutant library generation methods have been developed to improve mainly "localizable" enzyme properties such as activity and selectivity. Current multi-site saturation methods are restricted by the gene sequence, require subsequent PCR steps and/or additional enzymatic modifications. Here we report, a multiple site saturation mutagenesis method, OmniChange, which simultaneously and efficiently saturates five independent codons. As proof of principle, five chemically cleaved DNA fragments, each carrying one NNK-degenerated codon, were generated and assembled to full gene length in a one-pot-reaction without additional PCR-amplification or use of restriction enzymes or ligases. Sequencing revealed the presence of up to 27 different codons at individual positions, corresponding to 84.4% of the theoretical diversity offered by NNK-degeneration. OmniChange is absolutely sequence independent, does not require a minimal distance between mutated codons and can be accomplished within a day.
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Affiliation(s)
- Alexander Dennig
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Aachen, Germany
| | - Amol V. Shivange
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Aachen, Germany
| | - Jan Marienhagen
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Aachen, Germany
| | - Ulrich Schwaneberg
- Lehrstuhl für Biotechnologie, RWTH Aachen University, Aachen, Germany
- * E-mail:
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28
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Addington T, Calisto B, Alfonso-Prieto M, Rovira C, Fita I, Planas A. Re-engineering specificity in 1,3-1, 4-β-glucanase to accept branched xyloglucan substrates. Proteins 2010; 79:365-75. [DOI: 10.1002/prot.22884] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Putaporntip C, Jongwutiwes S, Thongaree S, Seethamchai S, Grynberg P, Hughes AL. Ecology of malaria parasites infecting Southeast Asian macaques: evidence from cytochrome b sequences. Mol Ecol 2010; 19:3466-76. [PMID: 20646216 DOI: 10.1111/j.1365-294x.2010.04756.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Although malaria parasites infecting non-human primates are important models for human malaria, little is known of the ecology of infection by these parasites in the wild. We extensively sequenced cytochrome b (cytb) of malaria parasites (Apicomplexa: Haemosporida) from free-living southeast Asian monkeys Macaca nemestrina and Macaca fascicularis. The two most commonly observed taxa were Plasmodium inui and Hepatocystis sp., but certain other sequences did not cluster closely with any previously sequenced species. Most of the major clades of parasites were found in both Macaca species, and the two most commonly occurring parasite infected the two Macaca species at approximately equal levels. However, P. inui showed evidence of genetic differentiation between the populations infecting the two Macaca species, suggesting limited movement of this parasite among hosts. Moreover, coinfection with Plasmodium and Hepatocystis species occurred significantly less frequently than expected on the basis of the rates of infection with either taxon alone, suggesting the possibility of competitive exclusion. The results revealed unexpectedly complex communities of Plasmodium and Hepatocystis taxa infecting wild southeast Asian monkeys. Parasite taxa differed with respect to both the frequency of between-host movement and their frequency of coinfection.
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Affiliation(s)
- Chaturong Putaporntip
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
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30
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A new method for multi-site-directed mutagenesis. Anal Biochem 2010; 406:83-5. [PMID: 20547136 DOI: 10.1016/j.ab.2010.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/08/2010] [Accepted: 06/08/2010] [Indexed: 11/22/2022]
Abstract
A modified method for multi-site-directed mutagenesis was developed here based on polymerase chain reaction (PCR), DpnI digestion, and overlap extension. It needs only methylated plasmids obtained by Dam methyltransferase or plasmids from dam(+)Escherichia coli containing target gene. The procedure consists of PCR, DpnI digestion, overlap extension PCR, and plasmid transformation. The method was developed for multi-site-directed mutagenesis, including close proximity of mutation sites. It does not require 5'-phosphorylated primers and ligation and, thus, significantly simplifies the routine work and reduces the experimental cost for multi-site-directed mutagenesis.
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31
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Simultaneous mutations up to six distal sites using a phosphorylation-free and ligase-free polymerase chain reaction-based mutagenesis. Anal Biochem 2010; 401:315-7. [DOI: 10.1016/j.ab.2010.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 11/20/2022]
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32
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Lu X, Hora B, Cai F, Gao F. Generation of random mutant libraries with multiple primers in a single reaction. J Virol Methods 2010; 167:146-51. [PMID: 20362002 DOI: 10.1016/j.jviromet.2010.03.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/23/2010] [Accepted: 03/24/2010] [Indexed: 11/26/2022]
Abstract
Characterization of multiple sites in a single gene that are important in biological phenotypes is challenging due to the difficulty to generate many mutants representing all or a majority of combinations of mutations in the gene. Using the HIV-1 env and pol genes as templates, four random libraries were generated representing different combinations of mutations introduced by up to 36 mutagenesis primers in a single assay. Over 86% of the clones contained mutations and the mutants tended to have single or fewer mutations in the libraries. When protein size was used as a screening marker, all identified clones contained at least 2 mutations and up to 12 mutations were detected in a single clone. Nearly all mutant clones in each library contained unique mutations, indicating that mutants in the library were generated at random. Closely related mutations which were overlapped by neighboring mutagenesis primers were often introduced in this system. Analysis of the env library showed that some potential N-linked glycosylation sites did not increase the Env molecular mass significantly, suggesting they were not used for glycosylation or only limited carbohydrate moieties were added at these sites. This novel method can serve as a powerful tool to study the biological phenotypes of genes whose functions are determined by multiple sites.
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Affiliation(s)
- Xiaozhi Lu
- Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
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33
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Fushan AA, Drayna DT. MALS: an efficient strategy for multiple site-directed mutagenesis employing a combination of DNA amplification, ligation and suppression PCR. BMC Biotechnol 2009; 9:83. [PMID: 19778447 PMCID: PMC2759926 DOI: 10.1186/1472-6750-9-83] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 09/24/2009] [Indexed: 11/18/2022] Open
Abstract
Background Multiple approaches for the site-directed mutagenesis (SDM) have been developed. However, only several of them are designed for simultaneous introduction of multiple nucleotide alterations, and these are time consuming. In addition, many of the existing multiple SDM methods have technical limitations associated with type and number of mutations that can be introduced, or are technically demanding and require special chemical reagents. Results In this study we developed a quick and efficient strategy for introduction of multiple complex mutations in a target DNA without intermediate subcloning by using a combination of connecting SDM and suppression PCR. The procedure consists of sequential rounds, with each individual round including PCR amplification of target DNA with two non-overlapping pairs of oligonucleotides. The desired mutation is incorporated at the 5' end of one or both internal oligonucleotides. DNA fragments obtained during amplification are mixed and ligated. The resulting DNA mixture is amplified with external oligonucleotides that act as suppression adapters. Suppression PCR limits amplification to DNA molecules representing full length target DNA, while amplification of other types of molecules formed during ligation is suppressed. To create additional mutations, an aliquot of the ligation mixture is then used directly for the next round of mutagenesis employing internal oligonucleotides specific for another region of target DNA. Conclusion A wide variety of complex multiple mutations can be generated in a short period of time. The procedure is rapid, highly efficient and does not require special chemical reagents. Thus, MALS represents a powerful alternative to the existing methods for multiple SDM.
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Affiliation(s)
- Alexey A Fushan
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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Zhang BZ, Zhang X, An XP, Ran DL, Zhou YS, Lu J, Tong YG. An easy-to-use site-directed mutagenesis method with a designed restriction site for convenient and reliable mutant screening. J Zhejiang Univ Sci B 2009; 10:479-82. [PMID: 19489114 DOI: 10.1631/jzus.b0820367] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Site-directed mutagenesis (SDM) has been a very important method to probe the function-structure relationship of proteins. In this study, we introduced an easy-to-use, polymerase chain reaction (PCR)-based SDM method for double-stranded plasmid DNA, with a designed restriction site to ensure simple and efficient mutant screening. The DNA sequence to be mutated was first translated into amino acid sequence and then the amino acid sequence was reversely translated into DNA sequence with degenerate codons, resulting in a large number of sequences with silent mutations, which contained various restriction endonuclease (RE) sites. Certain mutated sequence with an appropriate RE site was selected as the target DNA sequence for designing a pair of mutation primers to amplify the full-length plasmid via inverse PCR. The amplified product was 5'-phosphorylated, circularized, and transformed into an Escherichia coli host. The transformants were screened by digesting with the designed RE. This protocol uses only one pair of primers and only one PCR is conducted, without the need for hybridization with hazardous isotope for mutant screening or subcloning step.
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Affiliation(s)
- Bao-zhong Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
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LoVullo ED, Sherrill LA, Pavelka MS. Improved shuttle vectors for Francisella tularensis genetics. FEMS Microbiol Lett 2008; 291:95-102. [PMID: 19067747 DOI: 10.1111/j.1574-6968.2008.01440.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
We previously described the construction and characterization of Escherichia coli-Francisella tularensis shuttle vectors, derived from the cryptic Francisella plasmid pFNL10, for the genetic manipulation of F. tularensis ssp. tularensis. We now report further characterization of the biology of these shuttle vectors and the development of a new generation of Francisella plasmids. We show that the addition of ORF3 from pFNL10 can convert an unstable shuttle vector into a stable one, and that this is likely due to increased plasmid copy number. We also describe various improvements to the earlier generations of shuttle vectors, such as the addition of a multiple cloning site containing a novel RsrII restriction endonuclease site for directional insertion of Francisella genes, and the inclusion of the F. tularensis blaB promoter for heterologous gene expression.
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Affiliation(s)
- Eric D LoVullo
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Liu H, Naismith JH. An efficient one-step site-directed deletion, insertion, single and multiple-site plasmid mutagenesis protocol. BMC Biotechnol 2008; 8:91. [PMID: 19055817 PMCID: PMC2629768 DOI: 10.1186/1472-6750-8-91] [Citation(s) in RCA: 777] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Accepted: 12/04/2008] [Indexed: 11/24/2022] Open
Abstract
Background Mutagenesis plays an essential role in molecular biology and biochemistry. It has also been used in enzymology and protein science to generate proteins which are more tractable for biophysical techniques. The ability to quickly and specifically mutate a residue(s) in protein is important for mechanistic and functional studies. Although many site-directed mutagenesis methods have been developed, a simple, quick and multi-applicable method is still desirable. Results We have developed a site-directed plasmid mutagenesis protocol that preserved the simple one step procedure of the QuikChange™ site-directed mutagenesis but enhanced its efficiency and extended its capability for multi-site mutagenesis. This modified protocol used a new primer design that promoted primer-template annealing by eliminating primer dimerization and also permitted the newly synthesized DNA to be used as the template in subsequent amplification cycles. These two factors we believe are the main reasons for the enhanced amplification efficiency and for its applications in multi-site mutagenesis. Conclusion Our modified protocol significantly increased the efficiency of single mutation and also allowed facile large single insertions, deletions/truncations and multiple mutations in a single experiment, an option incompatible with the standard QuikChange™. Furthermore the new protocol required significantly less parental DNA which facilitated the DpnI digestion after the PCR amplification and enhanced the overall efficiency and reliability. Using our protocol, we generated single site, multiple single-site mutations and a combined insertion/deletion mutations. The results demonstrated that this new protocol imposed no additional reagent costs (beyond basic QuikChange™) but increased the overall success rates.
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Affiliation(s)
- Huanting Liu
- SSPF, Centre for Biomolecular Science, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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Wong TS, Roccatano D, Schwaneberg U. Steering directed protein evolution: strategies to manage combinatorial complexity of mutant libraries. Environ Microbiol 2007; 9:2645-59. [DOI: 10.1111/j.1462-2920.2007.01411.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Luo L, Tong X, Farley PC. The Candida albicans gene HGT12 (orf19.7094) encodes a hexose transporter. ACTA ACUST UNITED AC 2007; 51:14-7. [PMID: 17573928 DOI: 10.1111/j.1574-695x.2007.00274.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Yeast cells of the human pathogen Candida albicans that enter the bloodstream can be engulfed by macrophage cells but survive in, and can escape from, the phagolysosome. The C. albicans gene HGT12, which is specifically expressed during macrophage infection, encodes a protein that transports fructose, glucose and mannose. Expression of this hexose transporter along with the shift from glycolysis to gluconeogenesis that occurs in these phagocytosed cells suggests a requirement for glucose that can be supplied in part by uptake from the lumen of the phagolysosome.
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Affiliation(s)
- Lin Luo
- Institute of Molecular Biosciences, Massey University, New Zealand
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Kashima T, Rao N, Manley JL. An intronic element contributes to splicing repression in spinal muscular atrophy. Proc Natl Acad Sci U S A 2007; 104:3426-31. [PMID: 17307868 PMCID: PMC1805620 DOI: 10.1073/pnas.0700343104] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The neurodegenerative disease spinal muscular atrophy is caused by mutation of the survival motor neuron 1 (SMN1) gene. SMN2 is a nearly identical copy of SMN1 that is unable to prevent disease, because most SMN2 transcripts lack exon 7 and thus produce a nonfunctional protein. A key cause of inefficient SMN2 exon 7 splicing is a single nucleotide difference between SMN1 and SMN2 within exon 7. We previously provided evidence that this base change suppresses exon 7 splicing by creating an inhibitory element, a heterogeneous nuclear ribonucleoprotein (hnRNP) A1-dependent exonic splicing silencer. We now find that another rare nucleotide difference between SMN1 and SMN2, in intron 7, potentially creates a second SMN2-specific hnRNP A1 binding site. Remarkably, this single base change does indeed create a high-affinity hnRNP A1 binding site, and base substitutions that disrupt it restore exon 7 inclusion in vivo and prevent hnRNP A1 binding in vitro. We propose that interactions between hnRNP A1 molecules bound to the exonic and intronic sites cooperate to exclude exon 7 and discuss the significance of this exclusion with respect to SMN expression and splicing control more generally.
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Affiliation(s)
- Tsuyoshi Kashima
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Nishta Rao
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - James L. Manley
- Department of Biological Sciences, Columbia University, New York, NY 10027
- *To whom correspondence should be addressed. E-mail:
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Abstract
Facile "writing" of DNA fragments that encode entire gene sequences potentially has widespread applications in biological analysis and engineering. Rapid writing of open reading frames (ORFs) for expressed proteins could transform protein engineering and production for protein design, synthetic biology, and structural analysis. Here we present a process, protein fabrication automation (PFA), which facilitates the rapid de novo construction of any desired ORF from oligonucleotides with low effort, high speed, and little human interaction. PFA comprises software for sequence design, data management, and the generation of instruction sets for liquid-handling robotics, a liquid-handling robot, a robust PCR scheme for gene assembly from synthetic oligonucleotides, and a genetic selection system to enrich correctly assembled full-length synthetic ORFs. The process is robust and scalable.
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Affiliation(s)
- J Colin Cox
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Peng RH, Xiong AS, Yao QH. A direct and efficient PAGE-mediated overlap extension PCR method for gene multiple-site mutagenesis. Appl Microbiol Biotechnol 2006; 73:234-40. [PMID: 17021880 DOI: 10.1007/s00253-006-0583-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 07/10/2006] [Accepted: 07/11/2006] [Indexed: 01/21/2023]
Abstract
A simple, two-step efficient method to perform multiple-site mutagenesis of a gene from bacterial genome was developed. The method was named polyacrylamide gel electrophoresis (PAGE)-mediated overlap extension polymerase chain reaction (PCR) (POEP). The first step involves synthesis of individual fragments containing mutant sites with 15- to 25-bp overlap between two adjacent fragments. Mutations were introduced into the overlapping oligonucleotide primers which ensured the particular primer-template annealing. PAGE was used to remove contaminating parental templates, mispriming fragments, and leftover primers. The second step involves synthesis of the mutant full-length fragment. All purified PCR products from the first step were combined and used as the template for a second PCR using high-fidelity DNA polymerase, with the two outermost flanking oligonucleotides as primers. Using the POEP method, we have successfully introduced eight EcoRI sites into the Escherichia coli beta-galactosidase (Lac Z) gene. The overall rate of obtaining the multiple mutant sites was 100%. The POEP method is simple, involving only two steps, and reliable for multiple-site mutagenesis and is promising to be widely used in gene modification.
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Affiliation(s)
- Ri-He Peng
- Shanghai Key Laboratory of Agricultural Genetics and Breeding, Agro-Biotechnology Research Center, Shanghai Academy of Agricultural Sciences, 2901 Beidi Rd, Shanghai, People's Republic of China
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Liu L, Lomonossoff G. A site-directed mutagenesis method utilising large double-stranded DNA templates for the simultaneous introduction of multiple changes and sequential multiple rounds of mutation: Application to the study of whole viral genomes. J Virol Methods 2006; 137:63-71. [PMID: 16857273 DOI: 10.1016/j.jviromet.2006.05.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/25/2006] [Accepted: 05/30/2006] [Indexed: 11/30/2022]
Abstract
A new technique for conducting site-directed mutagenesis was developed. This method allows the colour selection of mutants through the simultaneous activation or deactivation of the alpha-peptide of beta-galactosidase. Double-stranded DNA plasmids containing large inserts (at least 6.4 kbp in the present experiments) can be used as the mutational template. The method can efficiently create mutations at multiple sites simultaneously and can be used to perform multiple rounds of mutation on the same construct. The utility of the method for the analysis of viral genomes was demonstrated by applying it to the mutagenesis of a full-length cDNA copy of RNA-1 of Cowpea mosaic virus (CPMV). Six single-site mutants were initially produced which gave a variety of phenotypes when inoculated on to plants. To confirm that the phenotypes were directly caused by the introduced mutations, a second round of mutagenesis was used to create revertants of two of the mutants. In both cases, the revertants had a wild-type phenotype, demonstrating that the original phenotype was, indeed, the result of the introduced mutation. Overall, the results show that the present technique is a powerful method for site-directed mutagenesis of large DNA fragments, such as whole viral genomes, for functional studies.
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Affiliation(s)
- Li Liu
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
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