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Elias M, Guan X, Hudson D, Bose R, Kwak J, Petrounia I, Touah K, Mansour S, Yue P, Errasti G, Delacroix T, Ghosh A, Chakrabarti R. Evolution of Organic Solvent-Resistant DNA Polymerases. ACS Synth Biol 2023; 12:3170-3188. [PMID: 37611245 DOI: 10.1021/acssynbio.2c00515] [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: 08/25/2023]
Abstract
The introduction of thermostable polymerases revolutionized the polymerase chain reaction (PCR) and biotechnology. However, many GC-rich genes cannot be PCR-amplified with high efficiency in water, irrespective of temperature. Although polar organic cosolvents can enhance nucleic acid polymerization and amplification by destabilizing duplex DNA and secondary structures, nature has not selected for the evolution of solvent-tolerant polymerase enzymes. Here, we used ultrahigh-throughput droplet-based selection and deep sequencing along with computational free-energy and binding affinity calculations to evolve Taq polymerase to generate enzymes that are both stable and highly active in the presence of organic cosolvents, resulting in up to 10% solvent resistance and over 100-fold increase in stability at 97.5 °C in the presence of 1,4-butanediol, as well as tolerance to up to 10 times higher concentrations of the potent cosolvents sulfolane and 2-pyrrolidone. Using these polymerases, we successfully amplified a broad spectrum of GC-rich templates containing regions with over 90% GC content, including templates recalcitrant to amplification with existing polymerases, even in the presence of cosolvents. We also demonstrated dramatically reduced GC bias in the amplification of genes with widely varying GC content in quantitative polymerase chain reaction (qPCR). By expanding the scope of solvent systems compatible with nucleic acid polymerization, these organic solvent-resistant polymerases enable a dramatic reduction of sequence bias not achievable through thermal resistance alone, with significant implications for a wide range of applications including sequencing and synthetic biology in mixed aqueous-organic media.
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Affiliation(s)
- Mohammed Elias
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Xiangying Guan
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Devin Hudson
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Rahul Bose
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Joon Kwak
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Ioanna Petrounia
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Kenza Touah
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Sourour Mansour
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Peng Yue
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
| | - Gauthier Errasti
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Thomas Delacroix
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
| | - Anisha Ghosh
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
- McGill University, 845 Rue Sherbrooke Ouest, Montreal, QC H3A 0G4, Canada
| | - Raj Chakrabarti
- Chakrabarti Advanced Technology, LLC, PMC Group Building, 1288 Route 73, Suite 110, Mount Laurel, New Jersey 08054, United States
- Center for Protein Engineering & Drug Discovery, PMC Isochem SAS, 32 Rue Lavoisier, Vert-Le-Petit 91710, France
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Wang Y, Shi Y, Hellinga HW, Beese LS. Thermally controlled intein splicing of engineered DNA polymerases provides a robust and generalizable solution for accurate and sensitive molecular diagnostics. Nucleic Acids Res 2023; 51:5883-5894. [PMID: 37166959 PMCID: PMC10287962 DOI: 10.1093/nar/gkad368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/18/2023] [Accepted: 05/09/2023] [Indexed: 05/12/2023] Open
Abstract
DNA polymerases are essential for nucleic acid synthesis, cloning, sequencing and molecular diagnostics technologies. Conditional intein splicing is a powerful tool for controlling enzyme reactions. We have engineered a thermal switch into thermostable DNA polymerases from two structurally distinct polymerase families by inserting a thermally activated intein domain into a surface loop that is integral to the polymerase active site, thereby blocking DNA or RNA template access. The fusion proteins are inactive, but retain their structures, such that the intein excises during a heat pulse delivered at 70-80°C to generate spliced, active polymerases. This straightforward thermal activation step provides a highly effective, one-component 'hot-start' control of PCR reactions that enables accurate target amplification by minimizing unwanted by-products generated by off-target reactions. In one engineered enzyme, derived from Thermus aquaticus DNA polymerase, both DNA polymerase and reverse transcriptase activities are controlled by the intein, enabling single-reagent amplification of DNA and RNA under hot-start conditions. This engineered polymerase provides high-sensitivity detection for molecular diagnostics applications, amplifying 5-6 copies of the tested DNA and RNA targets with >95% certainty. The design principles used to engineer the inteins can be readily applied to construct other conditionally activated nucleic acid processing enzymes.
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Affiliation(s)
- You Wang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Yuqian Shi
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Homme W Hellinga
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Lorena S Beese
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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Gantz M, Neun S, Medcalf EJ, van Vliet LD, Hollfelder F. Ultrahigh-Throughput Enzyme Engineering and Discovery in In Vitro Compartments. Chem Rev 2023; 123:5571-5611. [PMID: 37126602 PMCID: PMC10176489 DOI: 10.1021/acs.chemrev.2c00910] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Novel and improved biocatalysts are increasingly sourced from libraries via experimental screening. The success of such campaigns is crucially dependent on the number of candidates tested. Water-in-oil emulsion droplets can replace the classical test tube, to provide in vitro compartments as an alternative screening format, containing genotype and phenotype and enabling a readout of function. The scale-down to micrometer droplet diameters and picoliter volumes brings about a >107-fold volume reduction compared to 96-well-plate screening. Droplets made in automated microfluidic devices can be integrated into modular workflows to set up multistep screening protocols involving various detection modes to sort >107 variants a day with kHz frequencies. The repertoire of assays available for droplet screening covers all seven enzyme commission (EC) number classes, setting the stage for widespread use of droplet microfluidics in everyday biochemical experiments. We review the practicalities of adapting droplet screening for enzyme discovery and for detailed kinetic characterization. These new ways of working will not just accelerate discovery experiments currently limited by screening capacity but profoundly change the paradigms we can probe. By interfacing the results of ultrahigh-throughput droplet screening with next-generation sequencing and deep learning, strategies for directed evolution can be implemented, examined, and evaluated.
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Affiliation(s)
- Maximilian Gantz
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Stefanie Neun
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Elliot J Medcalf
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Liisa D van Vliet
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
| | - Florian Hollfelder
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Rd, Cambridge CB2 1GA, U.K
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Akram F, Shah FI, Ibrar R, Fatima T, Haq IU, Naseem W, Gul MA, Tehreem L, Haider G. Bacterial thermophilic DNA polymerases: A focus on prominent biotechnological applications. Anal Biochem 2023; 671:115150. [PMID: 37054862 DOI: 10.1016/j.ab.2023.115150] [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: 01/14/2023] [Revised: 02/24/2023] [Accepted: 04/03/2023] [Indexed: 04/15/2023]
Abstract
DNA polymerases are the enzymes able to replicate the genetic information in nucleic acid. As a result, they are necessary to copy the complete genome of every living creature before cell division and sustain the integrity of the genetic information throughout the life of each cell. Any organism that uses DNA as its genetic information, whether unicellular or multicellular, requires one or more thermostable DNA polymerases to thrive. Thermostable DNA polymerase is important in modern biotechnology and molecular biology because it results in methods such as DNA cloning, DNA sequencing, whole genome amplification, molecular diagnostics, polymerase chain reaction, synthetic biology, and single nucleotide polymorphism detection. There are at least 14 DNA-dependent DNA polymerases in the human genome, which is remarkable. These include the widely accepted, high-fidelity enzymes responsible for replicating the vast majority of genomic DNA and eight or more specialized DNA polymerases discovered in the last decade. The newly discovered polymerases' functions are still being elucidated. Still, one of its crucial tasks is to permit synthesis to resume despite the DNA damage that stops the progression of replication-fork. One of the primary areas of interest in the research field has been the quest for novel DNA polymerase since the unique features of each thermostable DNA polymerase may lead to the prospective creation of novel reagents. Furthermore, protein engineering strategies for generating mutant or artificial DNA polymerases have successfully generated potent DNA polymerases for various applications. In molecular biology, thermostable DNA polymerases are extremely useful for PCR-related methods. This article examines the role and importance of DNA polymerase in a variety of techniques.
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Affiliation(s)
- Fatima Akram
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan.
| | - Fatima Iftikhar Shah
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan; The University of Lahore, Pakistan
| | - Ramesha Ibrar
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
| | - Taseer Fatima
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
| | - Ikram Ul Haq
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan; Pakistan Academy of Sciences, Islamabad, Pakistan
| | - Waqas Naseem
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
| | - Mahmood Ayaz Gul
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
| | - Laiba Tehreem
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
| | - Ghanoor Haider
- Institute of Industrial Biotechnology, Government College University, Lahore, 54000, Pakistan
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Shirshikov FV, Bespyatykh JA. Loop-Mediated Isothermal Amplification: From Theory to Practice. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2022; 48:1159-1174. [PMID: 36590469 PMCID: PMC9788664 DOI: 10.1134/s106816202206022x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/01/2022] [Accepted: 06/17/2022] [Indexed: 12/24/2022]
Abstract
Increasing the accuracy of pathogen identification and reducing the duration of analysis remain relevant for modern molecular diagnostics up to this day. In laboratory and clinical practice, detection of pathogens mostly relies on methods of nucleic acid amplification, among which the polymerase chain reaction (PCR) is considered the "gold standard." Nevertheless, in some cases, isothermal amplification methods act as an alternative to PCR diagnostics. Upon more than thirty years of the development of isothermal DNA synthesis, the appearance of loop-mediated isothermal amplification (LAMP) has enabled new directions of in-field diagnostics of bacterial and viral infections. This review examines the key characteristics of the LAMP method and corresponding features in practice. We discuss the structure of LAMP amplicons with single-stranded loops, which have the sites for primer annealing under isothermal conditions. The latest achievements in the modification of the LAMP method are analyzed, which allow considering it as a unique platform for creating the next-generation diagnostic assays.
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Affiliation(s)
- F. V. Shirshikov
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 119435 Moscow, Russia
| | - J. A. Bespyatykh
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, 119435 Moscow, Russia
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6
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Lim Y, Park IH, Lee HH, Baek K, Lee BC, Cho G. Modified Taq polymerase for allele-specific ultra-sensitive detection of genetic variants. J Mol Diagn 2022; 24:1128-1142. [PMID: 36058471 DOI: 10.1016/j.jmoldx.2022.08.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 07/28/2022] [Accepted: 08/11/2022] [Indexed: 11/30/2022] Open
Abstract
Allele-specific polymerase chain reaction (AS-PCR) has been used as a simple, cost-effective method for genotyping and gene mapping in research and clinical settings. AS-PCR permits the detection of single nucleotide variants (SNVs) and indels owing to the selective extension of a perfectly matched primer (to the template DNA) over a mismatched primer. Thus, the mismatch discrimination power of the DNA polymerase is critical. Unfortunately, currently available polymerases often amplify some mismatched primer-template complexes as well as matched ones, obscuring allele-specific detection. To increase mismatch discrimination, we have generated mutations in the Thermus aquaticus (Taq) DNA polymerase, selected the most efficient variant, and evaluated its performance in SNP and cancer mutation genotyping. In addition, the primer design and reaction buffer conditions were optimized for allele-specific amplification. Our highly selective AS-PCR, which is based on an allele-discriminating priming system (ADPS) that leverages a Taq polymerase variant with optimized primers and reaction buffer, can detect mutations with mutant allele frequency as low as 0.01% in genomic DNA and 0.0001% in plasmid DNA. This method serves as a simple, fast, cost-effective, and ultra-sensitive way to detect SNVs and indels with low abundance.
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Affiliation(s)
- Youngshin Lim
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Il-Hyun Park
- GENECAST, 66 Chungmin-ro, Songpa-gu, Seoul, KOREA
| | - Huy-Ho Lee
- GENECAST, 66 Chungmin-ro, Songpa-gu, Seoul, KOREA
| | - Kyuwon Baek
- GENECAST, 66 Chungmin-ro, Songpa-gu, Seoul, KOREA
| | | | - Ginam Cho
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Stucki A, Vallapurackal J, Ward TR, Dittrich PS. Droplet Microfluidics and Directed Evolution of Enzymes: An Intertwined Journey. Angew Chem Int Ed Engl 2021; 60:24368-24387. [PMID: 33539653 PMCID: PMC8596820 DOI: 10.1002/anie.202016154] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Indexed: 12/12/2022]
Abstract
Evolution is essential to the generation of complexity and ultimately life. It relies on the propagation of the properties, traits, and characteristics that allow an organism to survive in a challenging environment. It is evolution that shaped our world over about four billion years by slow and iterative adaptation. While natural evolution based on selection is slow and gradual, directed evolution allows the fast and streamlined optimization of a phenotype under selective conditions. The potential of directed evolution for the discovery and optimization of enzymes is mostly limited by the throughput of the tools and methods available for screening. Over the past twenty years, versatile tools based on droplet microfluidics have been developed to address the need for higher throughput. In this Review, we provide a chronological overview of the intertwined development of microfluidics droplet-based compartmentalization methods and in vivo directed evolution of enzymes.
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Affiliation(s)
- Ariane Stucki
- Department of Biosystems Science and EngineeringETH ZurichMattenstrasse 26CH-4058BaselSwitzerland
- National Competence Center in Research (NCCR)Molecular Systems EngineeringBaselSwitzerland
| | - Jaicy Vallapurackal
- Department of ChemistryUniversity of BaselMattenstrasse 24aCH-4058BaselSwitzerland
- National Competence Center in Research (NCCR)Molecular Systems EngineeringBaselSwitzerland
| | - Thomas R. Ward
- Department of ChemistryUniversity of BaselMattenstrasse 24aCH-4058BaselSwitzerland
- National Competence Center in Research (NCCR)Molecular Systems EngineeringBaselSwitzerland
| | - Petra S. Dittrich
- Department of Biosystems Science and EngineeringETH ZurichMattenstrasse 26CH-4058BaselSwitzerland
- National Competence Center in Research (NCCR)Molecular Systems EngineeringBaselSwitzerland
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8
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Directed Evolution Methods for Enzyme Engineering. Molecules 2021; 26:molecules26185599. [PMID: 34577070 PMCID: PMC8470892 DOI: 10.3390/molecules26185599] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 11/22/2022] Open
Abstract
Enzymes underpin the processes required for most biotransformations. However, natural enzymes are often not optimal for biotechnological uses and must be engineered for improved activity, specificity and stability. A rich and growing variety of wet-lab methods have been developed by researchers over decades to accomplish this goal. In this review such methods and their specific attributes are examined.
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Stucki A, Vallapurackal J, Ward TR, Dittrich PS. Droplet Microfluidics and Directed Evolution of Enzymes: An Intertwined Journey. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016154] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Ariane Stucki
- Department of Biosystems Science and Engineering ETH Zurich Mattenstrasse 26 CH-4058 Basel Switzerland
- National Competence Center in Research (NCCR) Molecular Systems Engineering Basel Switzerland
| | - Jaicy Vallapurackal
- Department of Chemistry University of Basel Mattenstrasse 24a CH-4058 Basel Switzerland
- National Competence Center in Research (NCCR) Molecular Systems Engineering Basel Switzerland
| | - Thomas R. Ward
- Department of Chemistry University of Basel Mattenstrasse 24a CH-4058 Basel Switzerland
- National Competence Center in Research (NCCR) Molecular Systems Engineering Basel Switzerland
| | - Petra S. Dittrich
- Department of Biosystems Science and Engineering ETH Zurich Mattenstrasse 26 CH-4058 Basel Switzerland
- National Competence Center in Research (NCCR) Molecular Systems Engineering Basel Switzerland
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10
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Sidstedt M, Rådström P, Hedman J. PCR inhibition in qPCR, dPCR and MPS-mechanisms and solutions. Anal Bioanal Chem 2020; 412:2009-2023. [PMID: 32052066 PMCID: PMC7072044 DOI: 10.1007/s00216-020-02490-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/29/2020] [Accepted: 02/04/2020] [Indexed: 12/24/2022]
Abstract
DNA analysis has seen an incredible development in terms of instrumentation, assays and applications over the last years. Massively parallel sequencing (MPS) and digital PCR are now broadly applied in research and diagnostics, and quantitative PCR is used for more and more practises. All these techniques are based on in vitro DNA polymerization and fluorescence measurements. A major limitation for successful analysis is the various sample-related substances that interfere with the analysis, i.e. PCR inhibitors. PCR inhibition affects library preparation in MPS analysis and skews quantification in qPCR, and some inhibitors have been found to quench the fluorescence of the applied fluorophores. Here, we provide a deeper understanding of mechanisms of specific PCR inhibitors and how these impact specific analytical techniques. This background knowledge is necessary in order to take full advantage of modern DNA analysis techniques, specifically for analysis of samples with low amounts of template and high amounts of background material. The classical solution to handle PCR inhibition is to purify or dilute DNA extracts, which leads to DNA loss. Applying inhibitor-tolerant DNA polymerases, either single enzymes or blends, provides a more straightforward and powerful solution. This review includes mechanisms of specific PCR inhibitors as well as solutions to the inhibition problem in relation to cutting-edge DNA analysis.
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Affiliation(s)
- Maja Sidstedt
- Swedish National Forensic Centre, Swedish Police Authority, 581 94, Linköping, Sweden
| | - Peter Rådström
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden
| | - Johannes Hedman
- Swedish National Forensic Centre, Swedish Police Authority, 581 94, Linköping, Sweden.
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden.
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Wang J, Zuo J, Wahafu A, Wang MD, Li RC, Xie WF. Combined elevation of TRIB2 and MAP3K1 indicates poor prognosis and chemoresistance to temozolomide in glioblastoma. CNS Neurosci Ther 2019; 26:297-308. [PMID: 31318172 PMCID: PMC7053231 DOI: 10.1111/cns.13197] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/27/2019] [Accepted: 07/03/2019] [Indexed: 01/09/2023] Open
Abstract
Introduction Glioblastoma (GBM) is the most lethal primary malignant brain tumor in adults with poor survival due to acquired therapeutic resistance and rapid recurrence. Currently, the standard clinical strategy for glioma includes maximum surgical resection, radiotherapy, and temozolomide (TMZ) chemotherapy; however, the median survival of patients with GBM remains poor despite these comprehensive therapies. Therefore, the identification of new prognostic biomarkers is urgently needed to evaluate the malignancy and long‐term outcome of glioma. Aims To further investigate prognostic biomarkers and potential therapeutic targets for GBM. Results In this study, we identified tribbles pseudokinase 2 (TRIB2) as one of the genes that is most correlated with pathological classification, radioresistance, and TMZ resistance in glioma. Additionally, the expression of mitogen‐activated protein kinase kinase kinase 1 (MAP3K1) showed a strong correlation with TRIB2. Moreover, a combined increase in TRIB2 and MAP3K1 was observed in GBM and indicated a poor prognosis of patients with glioma. Finally, enriched TRIB2 expression and MAP3K1 expression were shown to be associated with resistance to TMZ and radiotherapy. Conclusion Combined elevation of TRIB2 and MAP3K1 could be novel prognostic biomarkers and potential therapeutic targets to evaluate the malignancy and long‐term outcomes of GBM.
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Affiliation(s)
- Jia Wang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Center of Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jie Zuo
- The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Alafate Wahafu
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Mao-de Wang
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Center of Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Rui-Chun Li
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Wan-Fu Xie
- Department of Neurosurgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
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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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13
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Aye SL, Fujiwara K, Ueki A, Doi N. Engineering of DNA polymerase I from Thermus thermophilus using compartmentalized self-replication. Biochem Biophys Res Commun 2018; 499:170-176. [PMID: 29550479 DOI: 10.1016/j.bbrc.2018.03.098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/13/2018] [Indexed: 11/30/2022]
Abstract
Although compartmentalized self-replication (CSR) and compartmentalized partnered replication (CPR) are powerful tools for directed evolution of proteins and gene circuits, limitations remain in the emulsion PCR process with the wild-type Taq DNA polymerase used so far, including long run times, low amounts of product, and false negative results due to inhibitors. In this study, we developed a high-efficiency mutant of DNA polymerase I from Thermus thermophilus HB27 (Tth pol) suited for CSR and CPR. We modified the wild-type Tth pol by (i) deletion of the N-terminal 5' to 3' exonuclease domain, (ii) fusion with the DNA-binding protein Sso7d, (iii) introduction of four known effective point mutations from other DNA polymerase mutants, and (iv) codon optimization to reduce the GC content. Consequently, we obtained a mutant that provides higher product yields than the conventional Taq pol without decreased fidelity. Next, we performed four rounds of CSR selection with a randomly mutated library of this modified Tth pol and obtained mutants that provide higher product yields in fewer cycles of emulsion PCR than the parent Tth pol as well as the conventional Taq pol.
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Affiliation(s)
- Seaim Lwin Aye
- Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Kei Fujiwara
- Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Asuka Ueki
- Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
| | - Nobuhide Doi
- Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan.
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14
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Sidstedt M, Hedman J, Romsos EL, Waitara L, Wadsö L, Steffen CR, Vallone PM, Rådström P. Inhibition mechanisms of hemoglobin, immunoglobulin G, and whole blood in digital and real-time PCR. Anal Bioanal Chem 2018; 410:2569-2583. [PMID: 29504082 PMCID: PMC5857286 DOI: 10.1007/s00216-018-0931-z] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/18/2018] [Accepted: 01/30/2018] [Indexed: 11/25/2022]
Abstract
Blood samples are widely used for PCR-based DNA analysis in fields such as diagnosis of infectious diseases, cancer diagnostics, and forensic genetics. In this study, the mechanisms behind blood-induced PCR inhibition were evaluated by use of whole blood as well as known PCR-inhibitory molecules in both digital PCR and real-time PCR. Also, electrophoretic mobility shift assay was applied to investigate interactions between inhibitory proteins and DNA, and isothermal titration calorimetry was used to directly measure effects on DNA polymerase activity. Whole blood caused a decrease in the number of positive digital PCR reactions, lowered amplification efficiency, and caused severe quenching of the fluorescence of the passive reference dye 6-carboxy-X-rhodamine as well as the double-stranded DNA binding dye EvaGreen. Immunoglobulin G was found to bind to single-stranded genomic DNA, leading to increased quantification cycle values. Hemoglobin affected the DNA polymerase activity and thus lowered the amplification efficiency. Hemoglobin and hematin were shown to be the molecules in blood responsible for the fluorescence quenching. In conclusion, hemoglobin and immunoglobulin G are the two major PCR inhibitors in blood, where the first affects amplification through a direct effect on the DNA polymerase activity and quenches the fluorescence of free dye molecules, and the latter binds to single-stranded genomic DNA, hindering DNA polymerization in the first few PCR cycles. Graphical abstract PCR inhibition mechanisms of hemoglobin and immunoglobulin G (IgG). Cq quantification cycle, dsDNA double-stranded DNA, ssDNA single-stranded DNA.
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Affiliation(s)
- Maja Sidstedt
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden
- Swedish National Forensic Centre, 581 94, Linköping, Sweden
| | - Johannes Hedman
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden.
- Swedish National Forensic Centre, 581 94, Linköping, Sweden.
| | - Erica L Romsos
- Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899-8314, USA
| | - Leticia Waitara
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden
- Government Chemist Laboratory Authority, P.O. Box 164, Dar es Salaam, Tanzania
| | - Lars Wadsö
- Division of Building Materials, Lund University, 221 00, Lund, Sweden
| | - Carolyn R Steffen
- Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899-8314, USA
| | - Peter M Vallone
- Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899-8314, USA
| | - Peter Rådström
- Applied Microbiology, Department of Chemistry, Lund University, P.O. Box 124, 221 00, Lund, Sweden
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15
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DNA polymerases and biotechnological applications. Curr Opin Biotechnol 2017; 48:187-195. [PMID: 28618333 DOI: 10.1016/j.copbio.2017.04.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 04/17/2017] [Indexed: 01/04/2023]
Abstract
A multitude of biotechnological techniques used in basic research as well as in clinical diagnostics on an everyday basis depend on DNA polymerases and their intrinsic capability to replicate DNA strands with astoundingly high fidelity. Applications with fundamental importance to modern molecular biology, including the polymerase chain reaction and DNA sequencing, would not be feasible without the advances made in characterizing these enzymes over the course of the last 60 years. Nonetheless, the still growing application scope of DNA polymerases necessitates the identification of novel enzymes with tailor-made properties. In the recent past, DNA polymerases optimized for diverse PCR and sequencing applications as well as enzymes that accept a variety of unnatural substrates for the synthesis and reverse transcription of modified nucleic acids have been developed.
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16
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Glasscock C, Lucks J, DeLisa M. Engineered Protein Machines: Emergent Tools for Synthetic Biology. Cell Chem Biol 2016; 23:45-56. [DOI: 10.1016/j.chembiol.2015.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/01/2015] [Accepted: 12/01/2015] [Indexed: 11/25/2022]
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17
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Gardner AF, Kelman Z. DNA polymerases in biotechnology. Front Microbiol 2014; 5:659. [PMID: 25520711 PMCID: PMC4249456 DOI: 10.3389/fmicb.2014.00659] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 11/13/2014] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - Zvi Kelman
- National Institute of Standards and Technology Gaithersburg, MD, USA ; Institute for Bioscience and Biotechnology Research Rockville, MD, USA
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18
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Reha-Krantz LJ, Woodgate S, Goodman MF. Engineering processive DNA polymerases with maximum benefit at minimum cost. Front Microbiol 2014; 5:380. [PMID: 25136334 PMCID: PMC4120765 DOI: 10.3389/fmicb.2014.00380] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 07/07/2014] [Indexed: 11/25/2022] Open
Abstract
DNA polymerases need to be engineered to achieve optimal performance for biotechnological applications, which often require high fidelity replication when using modified nucleotides and when replicating difficult DNA sequences. These tasks are achieved for the bacteriophage T4 DNA polymerase by replacing leucine with methionine in the highly conserved Motif A sequence (L412M). The costs are minimal. Although base substitution errors increase moderately, accuracy is maintained for templates with mono- and dinucleotide repeats while replication efficiency is enhanced. The L412M substitution increases intrinsic processivity and addition of phage T4 clamp and single-stranded DNA binding proteins further enhance the ability of the phage T4 L412M-DNA polymerase to replicate all types of difficult DNA sequences. Increased pyrophosphorolysis is a drawback of increased processivity, but pyrophosphorolysis is curbed by adding an inorganic pyrophosphatase or divalent metal cations, Mn2+ or Ca2+. In the absence of pyrophosphorolysis inhibitors, the T4 L412M-DNA polymerase catalyzed sequence-dependent pyrophosphorolysis under DNA sequencing conditions. The sequence specificity of the pyrophosphorolysis reaction provides insights into how the T4 DNA polymerase switches between nucleotide incorporation, pyrophosphorolysis and proofreading pathways. The L-to-M substitution was also tested in the yeast DNA polymerases delta and alpha. Because the mutant DNA polymerases displayed similar characteristics, we propose that amino acid substitutions in Motif A have the potential to increase processivity and to enhance performance in biotechnological applications. An underlying theme in this chapter is the use of genetic methods to identify mutant DNA polymerases with potential for use in current and future biotechnological applications.
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Affiliation(s)
- Linda J Reha-Krantz
- Department of Biological Sciences, University of Alberta Edmonton, AB, Canada
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