1
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Asin-Garcia E, Garcia-Morales L, Bartholet T, Liang Z, Isaacs F, Martins dos Santos VP. Metagenomics harvested genus-specific single-stranded DNA-annealing proteins improve and expand recombineering in Pseudomonas species. Nucleic Acids Res 2023; 51:12522-12536. [PMID: 37941137 PMCID: PMC10711431 DOI: 10.1093/nar/gkad1024] [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: 12/09/2022] [Revised: 10/14/2023] [Accepted: 10/30/2023] [Indexed: 11/10/2023] Open
Abstract
The widespread Pseudomonas genus comprises a collection of related species with remarkable abilities to degrade plastics and polluted wastes and to produce a broad set of valuable compounds, ranging from bulk chemicals to pharmaceuticals. Pseudomonas possess characteristics of tolerance and stress resistance making them valuable hosts for industrial and environmental biotechnology. However, efficient and high-throughput genetic engineering tools have limited metabolic engineering efforts and applications. To improve their genome editing capabilities, we first employed a computational biology workflow to generate a genus-specific library of potential single-stranded DNA-annealing proteins (SSAPs). Assessment of the library was performed in different Pseudomonas using a high-throughput pooled recombinase screen followed by Oxford Nanopore NGS analysis. Among different active variants with variable levels of allelic replacement frequency (ARF), efficient SSAPs were found and characterized for mediating recombineering in the four tested species. New variants yielded higher ARFs than existing ones in Pseudomonas putida and Pseudomonas aeruginosa, and expanded the field of recombineering in Pseudomonas taiwanensisand Pseudomonas fluorescens. These findings will enhance the mutagenesis capabilities of these members of the Pseudomonas genus, increasing the possibilities for biotransformation and enhancing their potential for synthetic biology applications. .
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Affiliation(s)
- Enrique Asin-Garcia
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen 6708 WE, The Netherlands
- Bioprocess Engineering Group, Wageningen University & Research, Wageningen 6700 AA, The Netherlands
| | - Luis Garcia-Morales
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen 6708 WE, The Netherlands
| | - Tessa Bartholet
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen 6708 WE, The Netherlands
| | - Zhuobin Liang
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA
| | - Farren J Isaacs
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA
| | - Vitor A P Martins dos Santos
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Wageningen 6708 WE, The Netherlands
- Bioprocess Engineering Group, Wageningen University & Research, Wageningen 6700 AA, The Netherlands
- LifeGlimmer GmbH, Berlin 12163, Germany
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2
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Al-Fatlawi A, Schroeder M, Stewart AF. The Rad52 SSAP superfamily and new insight into homologous recombination. Commun Biol 2023; 6:87. [PMID: 36690694 PMCID: PMC9870868 DOI: 10.1038/s42003-023-04476-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 01/12/2023] [Indexed: 01/25/2023] Open
Abstract
Recent structures of DNA-bound bacterial and phage recombinases provide insights into homologous recombination and suggest relation to the eukaryotic Rad52 and identification of a Rad52 single strand annealing protein (SSAP) superfamily.
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Affiliation(s)
- Ali Al-Fatlawi
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47, 01307, Dresden, Germany
| | - Michael Schroeder
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47, 01307, Dresden, Germany.
| | - A Francis Stewart
- Biotechnology Center, Center for Molecular and Cellular Bioengineering, Technische Universität Dresden, Tatzberg 47, 01307, Dresden, Germany.
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.
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3
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Caldwell BJ, Norris AS, Karbowski CF, Wiegand AM, Wysocki VH, Bell CE. Structure of a RecT/Redβ family recombinase in complex with a duplex intermediate of DNA annealing. Nat Commun 2022; 13:7855. [PMID: 36543802 PMCID: PMC9772228 DOI: 10.1038/s41467-022-35572-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Some bacteriophage encode a recombinase that catalyzes single-stranded DNA annealing (SSA). These proteins are apparently related to RAD52, the primary human SSA protein. The best studied protein, Redβ from bacteriophage λ, binds weakly to ssDNA, not at all to dsDNA, but tightly to a duplex intermediate of annealing formed when two complementary DNA strands are added to the protein sequentially. We used single particle cryo-electron microscopy (cryo-EM) to determine a 3.4 Å structure of a Redβ homolog from a prophage of Listeria innocua in complex with two complementary 83mer oligonucleotides. The structure reveals a helical protein filament bound to a DNA duplex that is highly extended and unwound. Native mass spectrometry confirms that the complex seen by cryo-EM is the predominant species in solution. The protein shares a common core fold with RAD52 and a similar mode of ssDNA-binding. These data provide insights into the mechanism of protein-catalyzed SSA.
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Affiliation(s)
- Brian J Caldwell
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, 43210, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Andrew S Norris
- Department of Chemistry and Biochemistry and Resource for Native MS-Guided Structural Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Caroline F Karbowski
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Alyssa M Wiegand
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Vicki H Wysocki
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, 43210, USA
- Department of Chemistry and Biochemistry and Resource for Native MS-Guided Structural Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Charles E Bell
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, 43210, USA.
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA.
- Department of Chemistry and Biochemistry and Resource for Native MS-Guided Structural Biology, The Ohio State University, Columbus, OH, 43210, USA.
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4
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Zakharova K, Caldwell BJ, Ta S, Wheat CT, Bell CE. Mutational Analysis of Redβ Single Strand Annealing Protein: Roles of the 14 Lysine Residues in DNA Binding and Recombination In Vivo. Int J Mol Sci 2021; 22:ijms22147758. [PMID: 34299376 PMCID: PMC8303780 DOI: 10.3390/ijms22147758] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/09/2021] [Accepted: 07/11/2021] [Indexed: 01/05/2023] Open
Abstract
Redβ is a 261 amino acid protein from bacteriophage λ that promotes a single-strand annealing (SSA) reaction for repair of double-stranded DNA (dsDNA) breaks. While there is currently no high-resolution structure available for Redβ, models of its DNA binding domain (residues 1-188) have been proposed based on homology with human Rad52, and a crystal structure of its C-terminal domain (CTD, residues 193-261), which binds to λ exonuclease and E. coli single-stranded DNA binding protein (SSB), has been determined. To evaluate these models, the 14 lysine residues of Redβ were mutated to alanine, and the variants tested for recombination in vivo and DNA binding and annealing in vitro. Most of the lysines within the DNA binding domain, including K36, K61, K111, K132, K148, K154, and K172, were found to be critical for DNA binding in vitro and recombination in vivo. By contrast, none of the lysines within the CTD, including K214, K245, K251, K253, and K258 were required for DNA binding in vitro, but two, K214 and K253, were critical for recombination in vivo, likely due to their involvement in binding to SSB. K61 was identified as a residue that is critical for DNA annealing, but not for initial ssDNA binding, suggesting a role in binding to the second strand of DNA incorporated into the complex. The K148A variant, which has previously been shown to be defective in oligomer formation, had the lowest affinity for ssDNA, and was the only variant that was completely non-cooperative, suggesting that ssDNA binding is coupled to oligomerization.
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Affiliation(s)
- Katerina Zakharova
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; (K.Z.); (B.J.C.); (S.T.); (C.T.W.)
| | - Brian J. Caldwell
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; (K.Z.); (B.J.C.); (S.T.); (C.T.W.)
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Shalya Ta
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; (K.Z.); (B.J.C.); (S.T.); (C.T.W.)
| | - Carter T. Wheat
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; (K.Z.); (B.J.C.); (S.T.); (C.T.W.)
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Charles E. Bell
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA; (K.Z.); (B.J.C.); (S.T.); (C.T.W.)
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- Correspondence:
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5
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Caldwell BJ, Norris A, Zakharova E, Smith CE, Wheat CT, Choudhary D, Sotomayor M, Wysocki VH, Bell CE. Oligomeric complexes formed by Redβ single strand annealing protein in its different DNA bound states. Nucleic Acids Res 2021; 49:3441-3460. [PMID: 33693865 PMCID: PMC8034648 DOI: 10.1093/nar/gkab125] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 02/09/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
Redβ is a single strand annealing protein from bacteriophage λ that binds loosely to ssDNA, not at all to pre-formed dsDNA, but tightly to a duplex intermediate of annealing. As viewed by electron microscopy, Redβ forms oligomeric rings on ssDNA substrate, and helical filaments on the annealed duplex intermediate. However, it is not clear if these are the functional forms of the protein in vivo. We have used size-exclusion chromatography coupled with multi-angle light scattering, analytical ultracentrifugation and native mass spectrometry (nMS) to characterize the size of the oligomers formed by Redβ in its different DNA-bound states. The nMS data, which resolve species with the highest resolution, reveal that Redβ forms an oligomer of 12 subunits in the absence of DNA, complexes ranging from 4 to 14 subunits on 38-mer ssDNA, and a much more distinct and stable complex of 11 subunits on 38-mer annealed duplex. We also measure the concentration of Redβ in cells active for recombination and find it to range from 7 to 27 μM. Collectively, these data provide new insights into the dynamic nature of the complex on ssDNA, and the more stable and defined complex on annealed duplex.
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Affiliation(s)
- Brian J Caldwell
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Andrew Norris
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Ekaterina Zakharova
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Christopher E Smith
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Carter T Wheat
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Deepanshu Choudhary
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Vicki H Wysocki
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Charles E Bell
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.,Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
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6
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Ramakrishnan S, Subramaniam S, Kielar C, Grundmeier G, Stewart AF, Keller A. Protein-Assisted Room-Temperature Assembly of Rigid, Immobile Holliday Junctions and Hierarchical DNA Nanostructures. Molecules 2020; 25:molecules25215099. [PMID: 33153073 PMCID: PMC7663122 DOI: 10.3390/molecules25215099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/30/2022] Open
Abstract
Immobile Holliday junctions represent not only the most fundamental building block of structural DNA nanotechnology but are also of tremendous importance for the in vitro investigation of genetic recombination and epigenetics. Here, we present a detailed study on the room-temperature assembly of immobile Holliday junctions with the help of the single-strand annealing protein Redβ. Individual DNA single strands are initially coated with protein monomers and subsequently hybridized to form a rigid blunt-ended four-arm junction. We investigate the efficiency of this approach for different DNA/protein ratios, as well as for different DNA sequence lengths. Furthermore, we also evaluate the potential of Redβ to anneal sticky-end modified Holliday junctions into hierarchical assemblies. We demonstrate the Redβ-mediated annealing of Holliday junction dimers, multimers, and extended networks several microns in size. While these hybrid DNA–protein nanostructures may find applications in the crystallization of DNA–protein complexes, our work shows the great potential of Redβ to aid in the synthesis of functional DNA nanostructures under mild reaction conditions.
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Affiliation(s)
- Saminathan Ramakrishnan
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (S.R.); (C.K.); (G.G.)
- Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Sivaraman Subramaniam
- Biotechnology Center, Department of Genomics, Technische Universität Dresden, Tatzberg 47-51, 01307 Dresden, Germany; (S.S.); (A.F.S.)
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01062 Dresden, Germany
| | - Charlotte Kielar
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (S.R.); (C.K.); (G.G.)
| | - Guido Grundmeier
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (S.R.); (C.K.); (G.G.)
| | - A. Francis Stewart
- Biotechnology Center, Department of Genomics, Technische Universität Dresden, Tatzberg 47-51, 01307 Dresden, Germany; (S.S.); (A.F.S.)
- Cluster of Excellence Physics of Life, Technische Universität Dresden, 01062 Dresden, Germany
| | - Adrian Keller
- Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany; (S.R.); (C.K.); (G.G.)
- Correspondence:
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7
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Brewster JL, Tolun G. Half a century of bacteriophage lambda recombinase: In vitro studies of lambda exonuclease and Red-beta annealase. IUBMB Life 2020; 72:1622-1633. [PMID: 32621393 PMCID: PMC7496540 DOI: 10.1002/iub.2343] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 06/10/2020] [Accepted: 06/10/2020] [Indexed: 01/03/2023]
Abstract
DNA recombination, replication, and repair are intrinsically interconnected processes. From viruses to humans, they are ubiquitous and essential to all life on Earth. Single‐strand annealing homologous DNA recombination is a major mechanism for the repair of double‐stranded DNA breaks. An exonuclease and an annealase work in tandem, forming a complex known as a two‐component recombinase. Redβ annealase and λ‐exonuclease from phage lambda form the archetypal two‐component recombinase complex. In this short review article, we highlight some of the in vitro studies that have led to our current understanding of the lambda recombinase system. We synthesize insights from more than half a century of research, summarizing the state of our current understanding. From this foundation, we identify the gaps in our knowledge and cast an eye forward to consider what the next 50 years of research may uncover.
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Affiliation(s)
- Jodi L Brewster
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Keiraville, New South Wales, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia
| | - Gökhan Tolun
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Keiraville, New South Wales, Australia.,Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia
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8
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Sudhakar S, Jachowski TJ, Kittelberger M, Maqbool A, Hermsdorf GL, Abdosamadi MK, Schäffer E. Supported Solid Lipid Bilayers as a Platform for Single-Molecule Force Measurements. NANO LETTERS 2019; 19:8877-8886. [PMID: 31746618 DOI: 10.1021/acs.nanolett.9b03761] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Biocompatible surfaces are important for basic and applied research in life science with experiments ranging from the organismal to the single-molecule level. For the latter, examples include the translocation of kinesin motor proteins along microtubule cytoskeletal filaments or the study of DNA-protein interactions. Such experiments often employ single-molecule fluorescence or force microscopy. In particular for force measurements, a key requirement is to prevent nonspecific interactions of biomolecules and force probes with the surface, while providing specific attachments that can sustain loads. Common approaches to reduce nonspecific interactions include supported lipid bilayers or PEGylated surfaces. However, fluid lipid bilayers do not support loads and PEGylation may require harsh chemical surface treatments and have limited reproducibility. Here, we developed and applied a supported solid lipid bilayer (SSLB) as a platform for specific, load bearing attachments with minimal nonspecific interactions. Apart from single-molecule fluorescence measurements, anchoring molecules to lipids in the solid phase enabled us to perform force measurements of molecular motors and overstretch DNA. Furthermore, using a heating laser, we could switch the SSLB to its fluid state allowing for manipulation of anchoring points. The assay had little nonspecific interactions, was robust, reproducible, and time-efficient, and required less hazardous and toxic chemicals for preparation. In the long term, we expect that SSLBs can be widely employed for single-molecule fluorescence microscopy, force spectroscopy, and cellular assays in mechanobiology.
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Affiliation(s)
- Swathi Sudhakar
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
| | - Tobias Jörg Jachowski
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
| | - Michael Kittelberger
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
| | - Ammara Maqbool
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
| | - Gero Lutz Hermsdorf
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
| | | | - Erik Schäffer
- Eberheard Karls Universität Tübingen , ZMBP , Auf der Morgenstelle 32 , 72076 Tübingen , Germany
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9
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Caldwell BJ, Bell CE. Structure and mechanism of the Red recombination system of bacteriophage λ. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:33-46. [PMID: 30904699 DOI: 10.1016/j.pbiomolbio.2019.03.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/05/2019] [Accepted: 03/15/2019] [Indexed: 01/27/2023]
Abstract
While much of this volume focuses on mammalian DNA repair systems that are directly involved in genome stability and cancer, it is important to still be mindful of model systems from prokaryotes. Herein we review the Red recombination system of bacteriophage λ, which consists of an exonuclease for resecting dsDNA ends, and a single-strand annealing protein (SSAP) for binding the resulting 3'-overhang and annealing it to a complementary strand. The genetics and biochemistry of Red have been studied for over 50 years, in work that has laid much of the foundation for understanding DNA recombination in higher eukaryotes. In fact, the Red exonuclease (λ exo) is homologous to Dna2, a nuclease involved in DNA end-resection in eukaryotes, and the Red annealing protein (Redβ) is homologous to Rad52, the primary SSAP in eukaryotes. While eukaryotic recombination involves an elaborate network of proteins that is still being unraveled, the phage systems are comparatively simple and streamlined, yet still encompass the fundamental features of recombination, namely DNA end-resection, homologous pairing (annealing), and a coupling between them. Moreover, the Red system has been exploited in powerful methods for bacterial genome engineering that are important for functional genomics and systems biology. However, several mechanistic aspects of Red, particularly the action of the annealing protein, remain poorly understood. This review will focus on the proteins of the Red recombination system, with particular attention to structural and mechanistic aspects, and how the lessons learned can be applied to eukaryotic systems.
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Affiliation(s)
- Brian J Caldwell
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210, USA; Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA
| | - Charles E Bell
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH, 43210, USA; Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA; Department of Chemistry and Biochemistry, 484 West 12th Avenue, 1060 Carmack Road, Columbus, OH, 43210, USA.
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10
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Caldwell BJ, Zakharova E, Filsinger GT, Wannier TM, Hempfling JP, Chun-Der L, Pei D, Church GM, Bell CE. Crystal structure of the Redβ C-terminal domain in complex with λ Exonuclease reveals an unexpected homology with λ Orf and an interaction with Escherichia coli single stranded DNA binding protein. Nucleic Acids Res 2019; 47:1950-1963. [PMID: 30624736 PMCID: PMC6393309 DOI: 10.1093/nar/gky1309] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/18/2018] [Accepted: 12/23/2018] [Indexed: 02/06/2023] Open
Abstract
Bacteriophage λ encodes a DNA recombination system that includes a 5'-3' exonuclease (λ Exo) and a single strand annealing protein (Redβ). The two proteins form a complex that is thought to mediate loading of Redβ directly onto the single-stranded 3'-overhang generated by λ Exo. Here, we present a 2.3 Å crystal structure of the λ Exo trimer bound to three copies of the Redβ C-terminal domain (CTD). Mutation of residues at the hydrophobic core of the interface disrupts complex formation in vitro and impairs recombination in vivo. The Redβ CTD forms a three-helix bundle with unexpected structural homology to phage λ Orf, a protein that binds to E. coli single-stranded DNA binding protein (SSB) to function as a recombination mediator. Based on this relationship, we found that Redβ binds to full-length SSB, and to a peptide corresponding to its nine C-terminal residues, in an interaction that requires the CTD. These results suggest a dual role of the CTD, first in binding to λ Exo to facilitate loading of Redβ directly onto the initial single-stranded DNA (ssDNA) at a 3'-overhang, and second in binding to SSB to facilitate annealing of the overhang to SSB-coated ssDNA at the replication fork.
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Affiliation(s)
- Brian J Caldwell
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH 43210, USA
| | - Ekaterina Zakharova
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH 43210, USA
| | - Gabriel T Filsinger
- Department of Systems Biology, Harvard Medical School, Cambridge, MA 02138, USA
| | - Timothy M Wannier
- Department of Genetics, Harvard Medical School, Cambridge, MA 02138, USA
| | - Jordan P Hempfling
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Lee Chun-Der
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - Dehua Pei
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
| | - George M Church
- Department of Genetics, Harvard Medical School, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Charles E Bell
- Ohio State Biochemistry Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA
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11
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Gene cloning and seamless site-directed mutagenesis using single-strand annealing (SSA). Appl Microbiol Biotechnol 2018; 102:10119-10126. [PMID: 30209551 DOI: 10.1007/s00253-018-9348-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/16/2018] [Accepted: 08/27/2018] [Indexed: 12/17/2022]
Abstract
The full length of interested genes can be usually cloned by assembling exons or RACE products through overlap PCR. However, the procedure requires multiple PCR steps, which are prone to random mutagenesis. Here, we present a novel SSA-based method for gene cloning and seamless site-directed mutagenesis. We firstly cloned the full-length coding sequence of Cashmere goat (Capra hircus) Hoxc13 gene by assembling exons amplified from genomic DNA. Secondly, we created a Hoxc13 loss-function mutant seamlessly and further illustrated that direct repeat length of 25 bp is enough to trigger the SSA repair in routine E. coli strains including DH5α, Trans1t1, JM109, and Top10. Moreover, we cloned another full-length mutant of Foxn1 gene from Cashmere goat cDNA using further shortened direct repeats of 19 bp. In summary, our study provided an alternative method to overcome the difficulties during overlap PCR in some particular cases for gene cloning.
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Helena JM, Joubert AM, Grobbelaar S, Nolte EM, Nel M, Pepper MS, Coetzee M, Mercier AE. Deoxyribonucleic Acid Damage and Repair: Capitalizing on Our Understanding of the Mechanisms of Maintaining Genomic Integrity for Therapeutic Purposes. Int J Mol Sci 2018; 19:E1148. [PMID: 29641431 PMCID: PMC5979424 DOI: 10.3390/ijms19041148] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/19/2018] [Accepted: 03/23/2018] [Indexed: 12/31/2022] Open
Abstract
Deoxyribonucleic acid (DNA) is the self-replicating hereditary material that provides a blueprint which, in collaboration with environmental influences, produces a structural and functional phenotype. As DNA coordinates and directs differentiation, growth, survival, and reproduction, it is responsible for life and the continuation of our species. Genome integrity requires the maintenance of DNA stability for the correct preservation of genetic information. This is facilitated by accurate DNA replication and precise DNA repair. DNA damage may arise from a wide range of both endogenous and exogenous sources but may be repaired through highly specific mechanisms. The most common mechanisms include mismatch, base excision, nucleotide excision, and double-strand DNA (dsDNA) break repair. Concurrent with regulation of the cell cycle, these mechanisms are precisely executed to ensure full restoration of damaged DNA. Failure or inaccuracy in DNA repair contributes to genome instability and loss of genetic information which may lead to mutations resulting in disease or loss of life. A detailed understanding of the mechanisms of DNA damage and its repair provides insight into disease pathogeneses and may facilitate diagnosis and the development of targeted therapies.
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Affiliation(s)
- Jolene Michelle Helena
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anna Margaretha Joubert
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Simone Grobbelaar
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Elsie Magdalena Nolte
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Marcel Nel
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Michael Sean Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology, South African Medical Research Council (SAMRC) Extramural Unit for Stem Cell Research and Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Magdalena Coetzee
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anne Elisabeth Mercier
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
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13
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Bugiel M, Mitra A, Girardo S, Diez S, Schäffer E. Measuring Microtubule Supertwist and Defects by Three-Dimensional-Force-Clamp Tracking of Single Kinesin-1 Motors. NANO LETTERS 2018; 18:1290-1295. [PMID: 29380607 DOI: 10.1021/acs.nanolett.7b04971] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Three-dimensional (3D) nanometer tracking of single biomolecules provides important information about their biological function. However, existing microscopy approaches often have only limited spatial or temporal precision and do not allow the application of defined loads. Here, we developed and applied a high-precision 3D-optical-tweezers force clamp to track in vitro the 3D motion of single kinesin-1 motor proteins along microtubules. To provide the motors with unimpeded access to the whole microtubule lattice, we mounted the microtubules on topographic surface features generated by UV-nanoimprint lithography. Because kinesin-1 motors processively move along individual protofilaments, we could determine the number of protofilaments the microtubules were composed of by measuring the helical pitches of motor movement on supertwisted microtubules. Moreover, we were able to identify defects in microtubules, most likely arising from local changes in the protofilament number. While it is hypothesized that microtubule supertwist and defects can severely influence the function of motors and other microtubule-associated proteins, the presented method allows for the first time to fully map the microtubule lattice in situ. This mapping allows the correlation of motor-filament interactions with the microtubule fine-structure. With the additional ability to apply loads, we expect our 3D-optical-tweezers force clamp to become a valuable tool for obtaining a wide range of information from other biological systems, inaccessible by two-dimensional and/or ensemble measurements.
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Affiliation(s)
- Michael Bugiel
- Eberhard Karls Universität Tübingen, ZMBP , Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Aniruddha Mitra
- Technische Universität Dresden, B CUBE - Center for Molecular Bioengineering and Center for Advancing Electronics Dresden , Arnoldstrasse 18, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics , Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Salvatore Girardo
- Technische Universität Dresden, BIOTEC - Center for Molecular and Cellular Bioengineering , Tatzberg 47/49, 01307 Dresden, Germany
| | - Stefan Diez
- Technische Universität Dresden, B CUBE - Center for Molecular Bioengineering and Center for Advancing Electronics Dresden , Arnoldstrasse 18, 01307 Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics , Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Erik Schäffer
- Eberhard Karls Universität Tübingen, ZMBP , Auf der Morgenstelle 32, 72076 Tübingen, Germany
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Human RAD52 Captures and Holds DNA Strands, Increases DNA Flexibility, and Prevents Melting of Duplex DNA: Implications for DNA Recombination. Cell Rep 2017; 18:2845-2853. [PMID: 28329678 PMCID: PMC5379009 DOI: 10.1016/j.celrep.2017.02.068] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/20/2017] [Accepted: 02/21/2017] [Indexed: 11/30/2022] Open
Abstract
Human RAD52 promotes annealing of complementary single-stranded DNA (ssDNA). In-depth knowledge of RAD52-DNA interaction is required to understand how its activity is integrated in DNA repair processes. Here, we visualize individual fluorescent RAD52 complexes interacting with single DNA molecules. The interaction with ssDNA is rapid, static, and tight, where ssDNA appears to wrap around RAD52 complexes that promote intra-molecular bridging. With double-stranded DNA (dsDNA), interaction is slower, weaker, and often diffusive. Interestingly, force spectroscopy experiments show that RAD52 alters the mechanics dsDNA by enhancing DNA flexibility and increasing DNA contour length, suggesting intercalation. RAD52 binding changes the nature of the overstretching transition of dsDNA and prevents DNA melting, which is advantageous for strand clamping during or after annealing. DNA-bound RAD52 is efficient at capturing ssDNA in trans. Together, these effects may help key steps in DNA repair, such as second-end capture during homologous recombination or strand annealing during RAD51-independent recombination reactions. RAD52 binds ssDNA rapidly and tightly using wrapping and bridging modes RAD52 binding to dsDNA is slower, weaker, and often diffusive RAD52 changes dsDNA mechanics and intercalates into the double helix RAD52 prevents DNA melting by clamping DNA strands
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15
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Valero-Rello A, López-Sanz M, Quevedo-Olmos A, Sorokin A, Ayora S. Molecular Mechanisms That Contribute to Horizontal Transfer of Plasmids by the Bacteriophage SPP1. Front Microbiol 2017; 8:1816. [PMID: 29018417 PMCID: PMC5615212 DOI: 10.3389/fmicb.2017.01816] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/06/2017] [Indexed: 01/02/2023] Open
Abstract
Natural transformation and viral-mediated transduction are the main avenues of horizontal gene transfer in Firmicutes. Bacillus subtilis SPP1 is a generalized transducing bacteriophage. Using this lytic phage as a model, we have analyzed how viral replication and recombination systems contribute to the transfer of plasmid-borne antibiotic resistances. Phage SPP1 DNA replication relies on essential phage-encoded replisome organizer (G38P), helicase loader (G39P), hexameric replicative helicase (G40P), recombinase (G35P) and in less extent on the partially dispensable 5′→3′ exonuclease (G34.1P), the single-stranded DNA binding protein (G36P) and the Holliday junction resolvase (G44P). Correspondingly, the accumulation of linear concatemeric plasmid DNA, and the formation of transducing particles were blocked in the absence of G35P, G38P, G39P, and G40P, greatly reduced in the G34.1P, G36P mutants, and slightly reduced in G44P mutants. In contrast, establishment of injected linear plasmid DNA in the recipient host was independent of viral-encoded functions. DNA homology between SPP1 and the plasmid, rather than a viral packaging signal, enhanced the accumulation of packagable plasmid DNA. The transfer efficiency was also dependent on plasmid copy number, and rolling-circle plasmids were encapsidated at higher frequencies than theta-type replicating plasmids.
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Affiliation(s)
- Ana Valero-Rello
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones CientíficasMadrid, Spain.,Micalis Institute, INRA, AgroParisTech, Universite Paris-SaclayJouy-en-Josas, France
| | - María López-Sanz
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Alvaro Quevedo-Olmos
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Alexei Sorokin
- Micalis Institute, INRA, AgroParisTech, Universite Paris-SaclayJouy-en-Josas, France
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones CientíficasMadrid, Spain
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Bugiel M, Jannasch A, Schäffer E. Implementation and Tuning of an Optical Tweezers Force-Clamp Feedback System. Methods Mol Biol 2017; 1486:109-136. [PMID: 27844427 DOI: 10.1007/978-1-4939-6421-5_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Feedback systems can be used to control the value of a system variable. In optical tweezers, active feedback is often implemented to either keep the position or tension applied to a single biomolecule constant. Here, we describe the implementation of the latter: an optical force-clamp setup that can be used to study the motion of processive molecular motors under a constant load. We describe the basics of a software-implemented proportional-integral-derivative (PID) controller, how to tune it, and how to determine its optimal feedback rate. Limitations, possible feed-forward applications, and extensions into two- and three-dimensional optical force clamps are discussed. The feedback is ultimately limited by thermal fluctuations and the compliance of the involved molecules. To investigate a particular mechanical process, understanding the basics and limitations of the feedback system will be helpful for choosing the proper feedback hardware, for optimizing the system parameters, and for the design of the experiment.
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Affiliation(s)
- Michael Bugiel
- Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany
| | - Anita Jannasch
- Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany
| | - Erik Schäffer
- Center for Plant Molecular Biology, Universität Tübingen, Auf der Morgenstelle 32, D-72076, Tübingen, Germany.
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Subramaniam S, Erler A, Fu J, Kranz A, Tang J, Gopalswamy M, Ramakrishnan S, Keller A, Grundmeier G, Müller D, Sattler M, Stewart AF. DNA annealing by Redβ is insufficient for homologous recombination and the additional requirements involve intra- and inter-molecular interactions. Sci Rep 2016; 6:34525. [PMID: 27708411 PMCID: PMC5052646 DOI: 10.1038/srep34525] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 08/15/2016] [Indexed: 01/09/2023] Open
Abstract
Single strand annealing proteins (SSAPs) like Redβ initiate homologous recombination by annealing complementary DNA strands. We show that C-terminally truncated Redβ, whilst still able to promote annealing and nucleoprotein filament formation, is unable to mediate homologous recombination. Mutations of the C-terminal domain were evaluated using both single- and double stranded (ss and ds) substrates in recombination assays. Mutations of critical amino acids affected either dsDNA recombination or both ssDNA and dsDNA recombination indicating two separable functions, one of which is critical for dsDNA recombination and the second for recombination per se. As evaluated by co-immunoprecipitation experiments, the dsDNA recombination function relates to the Redα-Redβ protein-protein interaction, which requires not only contacts in the C-terminal domain but also a region near the N-terminus. Because the nucleoprotein filament formed with C-terminally truncated Redβ has altered properties, the second C-terminal function could be due to an interaction required for functional filaments. Alternatively the second C-terminal function could indicate a requirement for a Redβ-host factor interaction. These data further advance the model for Red recombination and the proposition that Redβ and RAD52 SSAPs share ancestral and mechanistic roots.
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Affiliation(s)
| | - Axel Erler
- Genomics, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Jun Fu
- Genomics, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany.,Shandong University-Helmholtz Joint Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Shanda Nanlu 27, 250100 Jinan, People's Republic of China
| | - Andrea Kranz
- Genomics, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Jing Tang
- Genomics, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Mohanraj Gopalswamy
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Technische Universität München, Lichtenbergstr.4, 85747 Garching, Germany
| | - Saminathan Ramakrishnan
- Technical and Macromolecular Chemistry, University of Paderborn, Warburger Str. 100 33098 Paderborn, Germany
| | - Adrian Keller
- Technical and Macromolecular Chemistry, University of Paderborn, Warburger Str. 100 33098 Paderborn, Germany
| | - Guido Grundmeier
- Technical and Macromolecular Chemistry, University of Paderborn, Warburger Str. 100 33098 Paderborn, Germany
| | - Daniel Müller
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Mattenstraße 26, 4058 Basel, Switzerland
| | - Michael Sattler
- Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany and Center for Integrated Protein Science Munich (CIPSM), Department of Chemistry, Technische Universität München, Lichtenbergstr.4, 85747 Garching, Germany
| | - A Francis Stewart
- Genomics, Biotechnology Center, TU Dresden, Tatzberg 47/49, 01307 Dresden, Germany
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18
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Young K, Starling N, Cunningham D. Targeting deficient DNA damage repair in gastric cancer. Expert Opin Pharmacother 2016; 17:1757-66. [PMID: 27488684 DOI: 10.1080/14656566.2016.1217992] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Over recent years our understanding of DNA damage repair has evolved leading to an expansion of therapies attempting to exploit DNA damage repair deficiencies across multiple solid tumours. Gastric cancer has been identified as a tumour where a subgroup of patients demonstrates deficiencies in the homologous recombination pathway providing a potential novel treatment approach for this poor prognosis disease. AREA COVERED This review provides an overview of DNA damage repair and how this has been targeted to date in other tumour types exploiting the concept of synthetic lethality. This is followed by a discussion of how deficiencies in homologous recombination may be identified across tumour types and on recent progress in targeting DNA repair deficiencies in gastric cancer. EXPERT OPINION Gastric cancer remains a difficult malignancy to treat and the possibility of targeting deficient DNA repair in a subgroup of patients is an exciting prospect. Future combinations with immunotherapy and radiotherapy are appealing and appear to have a sound biological rationale. However, much work remains to be done to understand the significance of the genetic and epigenetic alterations involved, to elucidate the optimum predictive signatures or biomarkers and to consider means of overcoming treatment resistance.
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Affiliation(s)
- Kate Young
- a Department of Medicine , The Royal Marsden NHS Foundation Trust, GI and Lymphoma Unit , Sutton , UK
| | - Naureen Starling
- a Department of Medicine , The Royal Marsden NHS Foundation Trust, GI and Lymphoma Unit , Sutton , UK
| | - David Cunningham
- a Department of Medicine , The Royal Marsden NHS Foundation Trust, GI and Lymphoma Unit , Sutton , UK
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Robinson R. Destabilizing DNA during Rejoining Enhances Fidelity of Repair. PLoS Biol 2015; 13:e1002214. [PMID: 26271078 PMCID: PMC4535887 DOI: 10.1371/journal.pbio.1002214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A new study shows that during repair of DNA, the effect of a single-strand annealing protein is to destabilize DNA duplex formation so that annealing only occurs between perfectly matched strands; the protein then clamps the strands together for repair. Read the Research Article.
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Affiliation(s)
- Richard Robinson
- Freelance Science Writer, Sherborn, Massachusetts, United States of America
- * E-mail:
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