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Montaño SP, Rowland SJ, Fuller JR, Burke ME, MacDonald A, Boocock M, Stark W, Rice P. Structural basis for topological regulation of Tn3 resolvase. Nucleic Acids Res 2023; 51:1001-1018. [PMID: 36100255 PMCID: PMC9943657 DOI: 10.1093/nar/gkac733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 08/02/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
Site-specific DNA recombinases play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful synthetic biology tools. The simplest site-specific recombination systems will recombine any two cognate sites regardless of context. Other systems have evolved elaborate mechanisms, often sensing DNA topology, to ensure that only one of multiple possible recombination products is produced. The closely related resolvases from the Tn3 and γδ transposons have historically served as paradigms for the regulation of recombinase activity by DNA topology. However, despite many proposals, models of the multi-subunit protein-DNA complex (termed the synaptosome) that enforces this regulation have been unsatisfying due to a lack of experimental constraints and incomplete concordance with experimental data. Here, we present new structural and biochemical data that lead to a new, detailed model of the Tn3 synaptosome, and discuss how it harnesses DNA topology to regulate the enzymatic activity of the recombinase.
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Affiliation(s)
- Sherwin P Montaño
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sally-J Rowland
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK
| | - James R Fuller
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Mary E Burke
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK
| | - Alasdair I MacDonald
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK
| | - Martin R Boocock
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, University Avenue, Glasgow G12 8QQ, Scotland, UK
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
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Type III restriction enzymes cleave DNA by long-range interaction between sites in both head-to-head and tail-to-tail inverted repeat. Proc Natl Acad Sci U S A 2010; 107:9123-8. [PMID: 20435912 DOI: 10.1073/pnas.1001637107] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cleavage of viral DNA by the bacterial Type III Restriction-Modification enzymes requires the ATP-dependent long-range communication between a distant pair of DNA recognition sequences. The classical view is that Type III endonuclease activity is only activated by a pair of asymmetric sites in a specific head-to-head inverted repeat. Based on this assumption and due to the presence of helicase domains in Type III enzymes, various motor-driven DNA translocation models for communication have been suggested. Using both single-molecule and ensemble assays we demonstrate that Type III enzymes can also cleave DNA with sites in tail-to-tail repeat with high efficiency. The ability to distinguish both inverted repeat substrates from direct repeat substrates in a manner independent of DNA topology or accessory proteins can only be reconciled with an alternative sliding mode of communication.
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Kilbride EA, Burke ME, Boocock MR, Stark WM. Determinants of product topology in a hybrid Cre-Tn3 resolvase site-specific recombination system. J Mol Biol 2005; 355:185-95. [PMID: 16303133 DOI: 10.1016/j.jmb.2005.10.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2005] [Revised: 10/16/2005] [Accepted: 10/18/2005] [Indexed: 11/29/2022]
Abstract
Many natural DNA site-specific recombination systems achieve directionality and/or selectivity by making recombinants with a specific DNA topology. This property requires that the DNA architecture of the synapse and the mechanism of strand exchange are both under strict control. Previously we reported that Tn3 resolvase-mediated synapsis of the accessory binding sites from the Tn3 recombination site res can impose topological selectivity on Cre/loxP recombination. Here, we show that the topology of these reactions is profoundly affected by subtle changes in the hybrid recombination site les. Reversing the orientation of loxP relative to the res accessory sequence, or adding 4 bp to the DNA between loxP and the accessory sequence, can switch between two-noded and four-noded catenane products. By analysing Holliday junction intermediates, we show that the innate bias in the order of strand exchanges at loxP is maintained despite the changes in topology. We conclude that a specific synaptic structure formed by resolvase and the res accessory sequences permits Cre to align the adjoining loxP sites in several distinct ways, and that resolvase-mediated intertwining of the accessory sequences may be less than has been assumed previously.
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Affiliation(s)
- Elizabeth A Kilbride
- Institute of Biomedical & Life Sciences, University of Glasgow, 56 Dumbarton Road, Glasgow G11 6NU, Scotland, UK
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Abstract
Sin recombinase from Staphylococcus aureus acts selectively on directly repeated resH sites, assembling an intertwined synapse in which exactly three supercoils are trapped between the points of strand exchange. Resolution requires the two Sin binding sites in resH (site I, where strand exchange occurs, and site II) and a non-specific DNA-bending protein (e.g. Hbsu). We show that a single amino acid substitution in Sin (I100T) is sufficient to relax the normal requirements for site II and Hbsu. Using this hyperactive protein, and the variant recombination site resH(AT), we investigate the roles of site II and Hbsu in synapsis and strand exchange. We conclude that Sin bound at site II, and Hbsu, act together to control site I alignment and the topology of the synapse, and to stimulate strand exchange.
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Affiliation(s)
- Sally J Rowland
- University of Glasgow, Institute of Biomedical and Life Sciences, Division of Molecular Genetics, Anderson College, 56 Dumbarton Road, Glasgow G11 6NU, UK.
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Embleton ML, Vologodskii AV, Halford SE. Dynamics of DNA loop capture by the SfiI restriction endonuclease on supercoiled and relaxed DNA. J Mol Biol 2004; 339:53-66. [PMID: 15123420 DOI: 10.1016/j.jmb.2004.03.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Revised: 03/11/2004] [Accepted: 03/18/2004] [Indexed: 11/18/2022]
Abstract
The SfiI endonuclease is a prototype for DNA looping. It binds two copies of its recognition sequence and, if Mg(2+) is present, cuts both concertedly. Looping was examined here on supercoiled and relaxed forms of a 5.5 kb plasmid with three SfiI sites: sites 1 and 2 were separated by 0.4 kb, and sites 2 and 3 by 2.0 kb. SfiI converted this plasmid directly to the products cut at all three sites, though DNA species cleaved at one or two sites were formed transiently during a burst phase. The burst revealed three sets of doubly cut products, corresponding to the three possible pairings of sites. The equilibrium distribution between the different loops was evaluated from the burst phases of reactions initiated by adding MgCl(2) to SfiI bound to the plasmid. The short loop was favored over the longer loops, particularly on supercoiled DNA. The relative rates for loop capture were assessed after adding SfiI to solutions containing the plasmid and MgCl(2). On both supercoiled and relaxed DNA, the rate of loop capture across 0.4 kb was only marginally faster than over 2.0 kb or 2.4 kb. The relative strengths and rates of looping were compared to computer simulations of conformational fluctuations in DNA. The simulations concurred broadly with the experimental data, though they predicted that increasing site separations should cause a shallower decline in the equilibrium constants than was observed but a slightly steeper decline in the rates for loop capture. Possible reasons for these discrepancies are discussed.
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Affiliation(s)
- Michelle L Embleton
- Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
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