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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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2
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Rowland SJ, Boocock MR, Burke ME, Rice PA, Stark WM. The protein-protein interactions required for assembly of the Tn3 resolution synapse. Mol Microbiol 2021; 114:952-965. [PMID: 33405333 DOI: 10.1111/mmi.14579] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/20/2020] [Accepted: 07/20/2020] [Indexed: 11/29/2022]
Abstract
The site-specific recombinase Tn3 resolvase initiates DNA strand exchange when two res recombination sites and six resolvase dimers interact to form a synapse. The detailed architecture of this intricate recombination machine remains unclear. We have clarified which of the potential dimer-dimer interactions are required for synapsis and recombination, using a novel complementation strategy that exploits a previously uncharacterized resolvase from Bartonella bacilliformis ("Bart"). Tn3 and Bart resolvases recognize different DNA motifs, via diverged C-terminal domains (CTDs). They also differ substantially at N-terminal domain (NTD) surfaces involved in dimerization and synapse assembly. We designed NTD-CTD hybrid proteins, and hybrid res sites containing both Tn3 and Bart dimer binding sites. Using these components in in vivo assays, we demonstrate that productive synapsis requires a specific "R" interface involving resolvase NTDs at all three dimer-binding sites in res. Synapses containing mixtures of wild-type Tn3 and Bart resolvase NTD dimers are recombination-defective, but activity can be restored by replacing patches of Tn3 resolvase R interface residues with Bart residues, or vice versa. We conclude that the Tn3/Bart family synapse is assembled exclusively by R interactions between resolvase dimers, except for the one special dimer-dimer interaction required for catalysis.
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Affiliation(s)
- Sally-J Rowland
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, UK
| | - Martin R Boocock
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, UK
| | - Mary E Burke
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, UK
| | - Phoebe A Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, UK
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3
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Olorunniji FJ, McPherson AL, Rosser SJ, Smith MCM, Colloms SD, Stark WM. Control of serine integrase recombination directionality by fusion with the directionality factor. Nucleic Acids Res 2017; 45:8635-8645. [PMID: 28666339 PMCID: PMC5737554 DOI: 10.1093/nar/gkx567] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/29/2017] [Indexed: 11/13/2022] Open
Abstract
Bacteriophage serine integrases are extensively used in biotechnology and synthetic biology for assembly and rearrangement of DNA sequences. Serine integrases promote recombination between two different DNA sites, attP and attB, to form recombinant attL and attR sites. The 'reverse' reaction requires another phage-encoded protein called the recombination directionality factor (RDF) in addition to integrase; RDF activates attL × attR recombination and inhibits attP × attB recombination. We show here that serine integrases can be fused to their cognate RDFs to create single proteins that catalyse efficient attL × attR recombination in vivo and in vitro, whereas attP × attB recombination efficiency is reduced. We provide evidence that activation of attL × attR recombination involves intra-subunit contacts between the integrase and RDF moieties of the fusion protein. Minor changes in the length and sequence of the integrase-RDF linker peptide did not affect fusion protein recombination activity. The efficiency and single-protein convenience of integrase-RDF fusion proteins make them potentially very advantageous for biotechnology/synthetic biology applications. Here, we demonstrate efficient gene cassette replacement in a synthetic metabolic pathway gene array as a proof of principle.
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Affiliation(s)
- Femi J Olorunniji
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Arlene L McPherson
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Susan J Rosser
- SynthSys - Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Roger Land Building, The King's Buildings, Mayfield Road, Edinburgh EH9 3JD, UK
| | - Margaret C M Smith
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK
| | - Sean D Colloms
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
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4
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Abstract
Tyrosine site-specific recombinases (YRs) are widely distributed among prokaryotes and their viruses, and were thought to be confined to the budding yeast lineage among eukaryotes. However, YR-harboring retrotransposons (the DIRS and PAT families) and DNA transposons (Cryptons) have been identified in a variety of eukaryotes. The YRs utilize a common chemical mechanism, analogous to that of type IB topoisomerases, to bring about a plethora of genetic rearrangements with important physiological consequences in their respective biological contexts. A subset of the tyrosine recombinases has provided model systems for analyzing the chemical mechanisms and conformational features of the recombination reaction using chemical, biochemical, topological, structural, and single molecule-biophysical approaches. YRs with simple reaction requirements have been utilized to bring about programmed DNA rearrangements for addressing fundamental questions in developmental biology. They have also been employed to trace the topological features of DNA within high-order DNA interactions established by protein machines. The directed evolution of altered specificity YRs, combined with their spatially and temporally regulated expression, heralds their emergence as vital tools in genome engineering projects with wide-ranging biotechnological and medical applications.
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Abstract
Transposons of the Tn3 family form a widespread and remarkably homogeneous group of bacterial transposable elements in terms of transposition functions and an extremely versatile system for mediating gene reassortment and genomic plasticity owing to their modular organization. They have made major contributions to antimicrobial drug resistance dissemination or to endowing environmental bacteria with novel catabolic capacities. Here, we discuss the dynamic aspects inherent to the diversity and mosaic structure of Tn3-family transposons and their derivatives. We also provide an overview of current knowledge of the replicative transposition mechanism of the family, emphasizing most recent work aimed at understanding this mechanism at the biochemical level. Previous and recent data are put in perspective with those obtained for other transposable elements to build up a tentative model linking the activities of the Tn3-family transposase protein with the cellular process of DNA replication, suggesting new lines for further investigation. Finally, we summarize our current view of the DNA site-specific recombination mechanisms responsible for converting replicative transposition intermediates into final products, comparing paradigm systems using a serine recombinase with more recently characterized systems that use a tyrosine recombinase.
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Xer Site-Specific Recombination: Promoting Vertical and Horizontal Transmission of Genetic Information. Microbiol Spectr 2016; 2. [PMID: 26104463 DOI: 10.1128/microbiolspec.mdna3-0056-2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Two related tyrosine recombinases, XerC and XerD, are encoded in the genome of most bacteria where they serve to resolve dimers of circular chromosomes by the addition of a crossover at a specific site, dif. From a structural and biochemical point of view they belong to the Cre resolvase family of tyrosine recombinases. Correspondingly, they are exploited for the resolution of multimers of numerous plasmids. In addition, they are exploited by mobile DNA elements to integrate into the genome of their host. Exploitation of Xer is likely to be advantageous to mobile elements because the conservation of the Xer recombinases and of the sequence of their chromosomal target should permit a quite easy extension of their host range. However, it requires means to overcome the cellular mechanisms that normally restrict recombination to dif sites harbored by a chromosome dimer and, in the case of integrative mobile elements, to convert dedicated tyrosine resolvases into integrases.
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Abstract
ABSTRACT
In site-specific recombination, two short DNA sequences (‘sites’) are each cut at specific points in both strands, and the cut ends are rejoined to new partners. The enzymes that mediate recognition of the sites and the subsequent cutting and rejoining steps are called recombinases. Most recombinases fall into one of two families according to similarities of their protein sequences and mechanisms; these families are known as the tyrosine recombinases and the serine recombinases, the names referring to the conserved amino acid residue that attacks the DNA phosphodiester and becomes covalently linked to a DNA strand end during catalysis. This chapter gives an overview of our current understanding of the serine recombinases, their types, biological roles, structures, catalytic mechanisms, mechanisms of regulation, and applications.
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Choi W, Saha RP, Jang S, Harshey RM. Controlling DNA degradation from a distance: a new role for the Mu transposition enhancer. Mol Microbiol 2014; 94:595-608. [PMID: 25256747 DOI: 10.1111/mmi.12781] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2014] [Indexed: 11/30/2022]
Abstract
Phage Mu is unique among transposable elements in employing a transposition enhancer. The enhancer DNA segment is the site where the transposase MuA binds and makes bridging interactions with the two Mu ends, interwrapping the ends with the enhancer in a complex topology essential for assembling a catalytically active transpososome. The enhancer is also the site at which regulatory proteins control divergent transcription of genes that determine the phage lysis-lysogeny decision. Here we report a third function for the enhancer - that of regulating degradation of extraneous DNA attached to both ends of infecting Mu. This DNA is protected from nucleases by a phage protein until Mu integrates into the host chromosome, after which it is rapidly degraded. We find that leftward transcription at the enhancer, expected to disrupt its topology within the transpososome, blocks degradation of this DNA. Disruption of the enhancer would lead to the loss or dislocation of two non-catalytic MuA subunits positioned in the transpososome by the enhancer. We provide several lines of support for this inference, and conclude that these subunits are important for activating degradation of the flanking DNA. This work also reveals a role for enhancer topology in phage development.
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Affiliation(s)
- Wonyoung Choi
- Department of Molecular Biosciences & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA
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9
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Ma CH, Liu YT, Savva CG, Rowley PA, Cannon B, Fan HF, Russell R, Holzenburg A, Jayaram M. Organization of DNA partners and strand exchange mechanisms during Flp site-specific recombination analyzed by difference topology, single molecule FRET and single molecule TPM. J Mol Biol 2013; 426:793-815. [PMID: 24286749 DOI: 10.1016/j.jmb.2013.11.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 10/26/2022]
Abstract
Flp site-specific recombination between two target sites (FRTs) harboring non-homology within the strand exchange region does not yield stable recombinant products. In negatively supercoiled plasmids containing head-to-tail sites, the reaction produces a series of knots with odd-numbered crossings. When the sites are in head-to-head orientation, the knot products contain even-numbered crossings. Both types of knots retain parental DNA configuration. By carrying out Flp recombination after first assembling the topologically well defined Tn3 resolvase synapse, it is possible to determine whether these knots arise by a processive or a dissociative mechanism. The nearly exclusive products from head-to-head and head-to-tail oriented "non-homologous" FRT partners are a 4-noded knot and a 5-noded knot, respectively. The corresponding products from a pair of native (homologous) FRT sites are a 3-noded knot and a 4-noded catenane, respectively. These results are consistent with non-homology-induced two rounds of dissociative recombination by Flp, the first to generate reciprocal recombinants containing non-complementary base pairs and the second to produce parental molecules with restored base pairing. Single molecule fluorescence resonance energy transfer (smFRET) analysis of geometrically restricted FRTs, together with single molecule tethered particle motion (smTPM) assays of unconstrained FRTs, suggests that the sites are preferentially synapsed in an anti-parallel fashion. This selectivity in synapse geometry occurs prior to the chemical steps of recombination, signifying early commitment to a productive reaction path. The cumulative topological, smFRET and smTPM results have implications for the relative orientation of DNA partners and the directionality of strand exchange during recombination mediated by tyrosine site-specific recombinases.
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Affiliation(s)
- Chien-Hui Ma
- Section of Molecular Genetics and Microbiology, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yen-Ting Liu
- Section of Molecular Genetics and Microbiology, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Christos G Savva
- Microscopy and Imaging Center, Department of Biology and Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2257, USA
| | - Paul A Rowley
- Section of Molecular Genetics and Microbiology, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Brian Cannon
- Department of Chemistry and Biochemistry, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Hsiu-Fang Fan
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei 112, Taiwan
| | - Rick Russell
- Department of Chemistry and Biochemistry, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Andreas Holzenburg
- Microscopy and Imaging Center, Department of Biology and Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2257, USA
| | - Makkuni Jayaram
- Section of Molecular Genetics and Microbiology, Institute of Cell and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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Abstract
FtsK is a multifunctional protein, which, in Escherichia coli, co-ordinates the essential functions of cell division, DNA unlinking and chromosome segregation. Its C-terminus is a DNA translocase, the fastest yet characterized, which acts as a septum-localized DNA pump. FtsK's C-terminus also interacts with the XerCD site-specific recombinases which act at the dif site, located in the terminus region. The motor domain of FtsK is an active translocase in vitro, and, when incubated with XerCD and a supercoiled plasmid containing two dif sites, recombination occurs to give unlinked circular products. Despite years of research the mechanism for this novel form of topological filter remains unknown.
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11
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Chan KM, Liu YT, Ma CH, Jayaram M, Sau S. The 2 micron plasmid of Saccharomyces cerevisiae: A miniaturized selfish genome with optimized functional competence. Plasmid 2013; 70:2-17. [DOI: 10.1016/j.plasmid.2013.03.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/21/2013] [Accepted: 03/02/2013] [Indexed: 01/24/2023]
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12
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Abstract
Difference topology is an experimental technique that can be used to unveil the topological structure adopted by two or more DNA segments in a stable protein–DNA complex. Difference topology has also been used to detect intermediates in a reaction pathway and to investigate the role of DNA supercoiling. In the present article, we review difference topology as applied to the Mu transpososome. The tools discussed can be applied to any stable nucleoprotein complex.
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14
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Olorunniji FJ, He J, Wenwieser SVCT, Boocock MR, Stark WM. Synapsis and catalysis by activated Tn3 resolvase mutants. Nucleic Acids Res 2008; 36:7181-91. [PMID: 19015124 PMCID: PMC2602789 DOI: 10.1093/nar/gkn885] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The serine recombinase Tn3 resolvase catalyses recombination between two 114 bp res sites, each of which contains binding sites for three resolvase dimers. We have analysed the in vitro properties of resolvase variants with ‘activating’ mutations, which can catalyse recombination at binding site I of res when the rest of res is absent. Site I × site I recombination promoted by these variants can be as fast as res×res recombination promoted by wild-type resolvase. Activated variants have reduced topological selectivity and no longer require the 2–3′ interface between subunits that is essential for wild-type resolvase-mediated recombination. They also promote formation of a stable synapse comprising a resolvase tetramer and two copies of site I. Cleavage of the DNA strands by the activated mutants is slow relative to the rate of synapsis. Stable resolvase tetramers were not detected in the absence of DNA or bound to a single site I. Our results lead us to conclude that the synapse is assembled by sequential binding of resolvase monomers to site I followed by interaction of two site I-dimer complexes. We discuss the implications of our results for the mechanisms of synapsis and regulation in recombination by wild-type resolvase.
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Affiliation(s)
- Femi J Olorunniji
- Faculty of Biomedical & Life Sciences, University of Glasgow, Glasgow, Scotland, UK
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15
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Mouw KW, Rowland SJ, Gajjar MM, Boocock MR, Stark WM, Rice PA. Architecture of a serine recombinase-DNA regulatory complex. Mol Cell 2008; 30:145-55. [PMID: 18439894 PMCID: PMC2428073 DOI: 10.1016/j.molcel.2008.02.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 01/12/2008] [Accepted: 02/28/2008] [Indexed: 01/07/2023]
Abstract
An essential feature of many site-specific recombination systems is their ability to regulate the direction and topology of recombination. Resolvases from the serine recombinase family assemble an interwound synaptic complex that harnesses negative supercoiling to drive the forward reaction and promote recombination between properly oriented sites. To better understand the interplay of catalytic and regulatory functions within these synaptic complexes, we have solved the structure of the regulatory site synapse in the Sin resolvase system. It reveals an unexpected synaptic interface between helix-turn-helix DNA-binding domains that is also highlighted in a screen for synapsis mutants. The tetramer defined by this interface provides the foundation for a robust model of the synaptic complex, assembled entirely from available crystal structures, that gives insight into how the catalytic activity of Sin and other serine recombinases may be regulated.
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Affiliation(s)
- Kent W. Mouw
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sally-J. Rowland
- Division of Molecular Genetics, FBLS, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Mark M. Gajjar
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Martin R. Boocock
- Division of Molecular Genetics, FBLS, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - W. Marshall Stark
- Division of Molecular Genetics, FBLS, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Phoebe A. Rice
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
- Corresponding author
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16
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MacDonald AI, Lu Y, Kilbride EA, Akopian A, Colloms SD. PepA and ArgR do not regulate Cre recombination at the bacteriophage P1 loxP site. Plasmid 2008; 59:119-26. [PMID: 18226834 PMCID: PMC2409434 DOI: 10.1016/j.plasmid.2007.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 11/27/2007] [Accepted: 12/04/2007] [Indexed: 11/17/2022]
Abstract
In the lysogenic state, bacteriophage P1 is maintained as a low copy-number circular plasmid. Site-specific recombination at loxP by the phage-encoded Cre protein keeps P1 monomeric, thus helping to ensure stable plasmid inheritance. Two Escherichia coli DNA-binding proteins, PepA and ArgR, were recently reported to be necessary for maintenance or establishment of P1 lysogeny. PepA and ArgR bind to regulatory DNA sequences upstream of the ColE1 cer recombination site to regulate site-specific recombination by the XerCD recombinases. This recombination keeps ColE1 in a monomeric state and helps to ensure stable plasmid maintenance. It has been suggested that ArgR and PepA play a similar role in P1 maintenance, regulating Cre recombination by binding to DNA sequences upstream of loxP. Here, we show that ArgR does not bind to its proposed binding site upstream of loxP, and that Cre recombination at loxP in its natural P1 context is not affected by PepA and ArgR in vitro. When sequences upstream of loxP were mutated to allow ArgR binding, PepA and ArgR still had no effect on Cre recombination. Our results demonstrate that PepA requires specific DNA sequences for binding, and that PepA and ArgR have no direct role in Cre recombination at P1 loxP.
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17
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Yin Z, Suzuki A, Lou Z, Jayaram M, Harshey RM. Interactions of phage Mu enhancer and termini that specify the assembly of a topologically unique interwrapped transpososome. J Mol Biol 2007; 372:382-96. [PMID: 17669422 DOI: 10.1016/j.jmb.2007.06.086] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 06/25/2007] [Accepted: 06/27/2007] [Indexed: 11/26/2022]
Abstract
The higher-order DNA-protein complex that carries out the chemical steps of phage Mu transposition is organized by bridging interactions among three DNA sites, the left (L) and right (R) ends of Mu, and an enhancer element (E), mediated by the transposase protein MuA. A subset of the six subunits of MuA associated with their cognate sub-sites at L and R communicate with the enhancer to trigger the stepwise assembly of the functional transpososome. The DNA follows a well-defined path within the transpososome, trapping five supercoil nodes comprising two E-R crossings, one E-L crossing and two L-R crossings. The enhancer is a critical DNA element in specifying the unique interwrapped topology of the three-site LER synapse. In this study, we used multiple strategies to characterize Mu end-enhancer interactions to extend, modify and refine those inferred from earlier analyses. Directed placement of transposase subunits at their cognate sub-sites at L and R, analysis of the protein composition of transpososomes thus obtained, and their characterization using topological methods define the following interactions. R1-E interaction is essential to promote transpososome assembly, R3-E interaction contributes to the native topology of the transpososome, and L1-E and R2-E interactions are not required for assembly. The data on L2-E and L3-E interactions are not unequivocal. If they do occur, either one is sufficient to support the assembly process. Our results are consistent with two R-E and perhaps one L-E, being responsible for the three DNA crossings between the enhancer and the left and right ends of Mu. A 3D representation of the interwrapped complex (IW) obtained by modeling is consistent with these results. The model reveals straightforward geometric and topological relationships between the IW complex and a more relaxed enhancer-independent V-form of the transpososome assembled under altered reaction conditions.
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Affiliation(s)
- Zhiqi Yin
- Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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18
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Du Q, Livshits A, Kwiatek A, Jayaram M, Vologodskii A. Protein-induced local DNA bends regulate global topology of recombination products. J Mol Biol 2007; 368:170-82. [PMID: 17337001 PMCID: PMC1945176 DOI: 10.1016/j.jmb.2007.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 02/05/2007] [Indexed: 11/21/2022]
Abstract
The tyrosine family of recombinases produces two smaller DNA circles when acting on circular DNA harboring two recombination sites in head-to-tail orientation. If the substrate is supercoiled, these circles can be unlinked or form multiply linked catenanes. The topological complexity of the products varies strongly even for similar recombination systems. This dependence has been solved here. Our computer simulation of the synapsis showed that the bend angles, phi, created in isolated recombination sites by protein binding before assembly of the full complex, determine the product topology. To verify the validity of this theoretical finding we measured the values of phi for Cre/loxP and Flp/FRT systems. The measurement was based on cyclization of the protein-bound short DNA fragments in solution. Despite the striking similarity of the synapses for these recombinases, action of Cre on head-to-tail target sites produces mainly unlinked circles, while that of Flp yields multiply linked catenanes. In full agreement with theoretical expectations we found that the values of phi for these systems are very different, close to 35 degrees and 80 degrees, respectively. Our findings have general implications in how small protein machines acting locally on large DNA molecules exploit statistical properties of their substrates to bring about directed global changes in topology.
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Affiliation(s)
- Quan Du
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Alexei Livshits
- Department of Chemistry, New York University, New York, NY 10003, USA
| | - Agnieszka Kwiatek
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
| | - Makkuni Jayaram
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
| | - Alexander Vologodskii
- Department of Chemistry, New York University, New York, NY 10003, USA
- *To whom correspondence should be addressed:
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19
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Abstract
Integration, excision, and inversion of defined DNA segments commonly occur through site-specific recombination, a process of DNA breakage and reunion that requires no DNA synthesis or high-energy cofactor. Virtually all identified site-specific recombinases fall into one of just two families, the tyrosine recombinases and the serine recombinases, named after the amino acid residue that forms a covalent protein-DNA linkage in the reaction intermediate. Their recombination mechanisms are distinctly different. Tyrosine recombinases break and rejoin single strands in pairs to form a Holliday junction intermediate. By contrast, serine recombinases cut all strands in advance of strand exchange and religation. Many natural systems of site-specific recombination impose sophisticated regulatory mechanisms on the basic recombinational process to favor one particular outcome of recombination over another (for example, excision over inversion or deletion). Details of the site-specific recombination processes have been revealed by recent structural and biochemical studies of members of both families.
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Affiliation(s)
- Nigel D F Grindley
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
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20
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Abstract
Phage Mu is the most efficient transposable element known, its high efficiency being conferred by an enhancer DNA element. Transposition is the end result of a series of well choreographed steps that juxtapose the enhancer and the two Mu ends within a nucleoprotein complex called the 'transpososome.' The particular arrangement of DNA and protein components lends extraordinary stability to the transpososome and regulates the frequency, precision, directionality, and mechanism of transposition. The structure of the transpososome, therefore, holds the key to understanding all of these attributes, and ultimately to explaining the runaway genetic success of transposable elements throughout the biological world. This review focuses on the path of the DNA within the Mu transpososome, as uncovered by recent topological analyses. It discusses why Mu topology cannot be analyzed by standard methods, and how knowledge of the geometry of site alignment during Flp and Cre site-specific recombination was harnessed to design a new methodology called 'difference topology.' This methodology has also revealed the order and dynamics of association of the three interacting DNA sites, as well as the role of the enhancer in assembly of the Mu transpososome.
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Affiliation(s)
- Rasika M Harshey
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, TX, USA.
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21
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Gelato KA, Martin SS, Wong S, Baldwin EP. Multiple levels of affinity-dependent DNA discrimination in Cre-LoxP recombination. Biochemistry 2006; 45:12216-26. [PMID: 17014075 PMCID: PMC2891539 DOI: 10.1021/bi0605235] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Cre recombinase residue Arg259 mediates a canonical bidentate hydrogen-bonded contact with Gua27 of its LoxP DNA substrate. Substituting Cyt8-Gua27 with the three other basepairs, to give LoxAT, LoxTA, and LoxGC, reduced Cre-mediated recombination in vitro, with the preference order of Gua27 > Ade27 approximately Thy27 >> Cyt27. While LoxAT and LoxTA exhibited 2.5-fold reduced affinity and 2.5-5-fold slower reaction rates, LoxGC was a barely functional substrate. Its maximum level of turnover was 6-fold reduced over other substrates, and it exhibited 8.5-fold reduced Cre binding and 6.3-fold slower turnover rate. With LoxP, the rate-limiting step for recombination occurs after protein-DNA complex assembly but before completion of the first strand exchange to form the Holliday junction (HJ) intermediate. With the mutant substrates, it occurs after HJ formation. Using an increased DNA-binding E262Q/E266Q "CreQQ" variant, all four substrates react more readily, but with much less difference between them, and maintained the earlier rate-limiting step. The data indicate that Cre discriminates substrates through differences in (i) concentration dependence of active complex assembly, (ii) turnover rate, and (iii) maximum yield of product at saturation, all of which are functions of the Cre-DNA binding interaction. CreQQ suppression of Lox mutant defects implies that coupling between binding and turnover involves a change in Cre subunit DNA affinities during the "conformational switch" that occurs prior to the second strand exchange. These results provide an example of how a DNA-binding enzyme can exert specificity via affinity modulation of conformational transitions that occur along its reaction pathway.
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Affiliation(s)
| | | | | | - Enoch P. Baldwin
- Corresponding author: Phone: (530) 752-1108. FAX (530) 752-3085.
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22
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Darcy IK, Chang J, Druivenga N, McKinney C, Medikonduri RK, Mills S, Navarra-Madsen J, Ponnusamy A, Sweet J, Thompson T. Coloring the Mu transpososome. BMC Bioinformatics 2006; 7:435. [PMID: 17022825 PMCID: PMC1636074 DOI: 10.1186/1471-2105-7-435] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Accepted: 10/05/2006] [Indexed: 11/15/2022] Open
Abstract
Background Tangle analysis has been applied successfully to study proteins which bind two segments of DNA and can knot and link circular DNA. We show how tangle analysis can be extended to model any stable protein-DNA complex. Results We discuss a computational method for finding the topological conformation of DNA bound within a protein complex. We use an elementary invariant from knot theory called colorability to encode and search for possible DNA conformations. We apply this method to analyze the experimental results of Pathania, Jayaram, and Harshey (Cell 2002). We show that the only topological DNA conformation bound by Mu transposase which is biologically likely is the five crossing solution found by Pathania et al (although other possibilities are discussed). Conclusion Our algorithm can be used to analyze the results of the experimental technique described in Pathania et al in order to determine the topological conformation of DNA bound within a stable protein-DNA complex.
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Affiliation(s)
- Isabel K Darcy
- Mathematics Department, University of Iowa, Iowa City, IA 52242, USA
| | - Jeff Chang
- Mathematics Department, University of Texas at Austin, Austin, TX 78712, USA
| | - Nathan Druivenga
- Mathematics Department, Indiana University, Bloomington, IN 47405, USA
| | - Colin McKinney
- Mathematics Department, University of Iowa, Iowa City, IA 52242, USA
| | - Ram K Medikonduri
- Mathematics Department, University of Iowa, Iowa City, IA 52242, USA
| | - Stacy Mills
- Mathematics Department, Florida State University, Tallahassee, FL 32306, USA
| | | | | | - Jesse Sweet
- Mathematics Department, University of Texas at Austin, Austin, TX 78712, USA
| | - Travis Thompson
- Mathematics Department, University of Iowa, Iowa City, IA 52242, USA
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23
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Vanhooff V, Galloy C, Agaisse H, Lereclus D, Révet B, Hallet B. Self-control in DNA site-specific recombination mediated by the tyrosine recombinase TnpI. Mol Microbiol 2006; 60:617-29. [PMID: 16629665 DOI: 10.1111/j.1365-2958.2006.05127.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tn4430 is a distinctive transposon of the Tn3 family that encodes a tyrosine recombinase (TnpI) to resolve replicative transposition intermediates. The internal resolution site of Tn4430 (IRS, 116 bp) contains two inverted repeats (IR1 and IR2) at the crossover core site, and two additional TnpI binding motifs (DR1 and DR2) adjacent to the core. Deletion analysis demonstrated that DR1 and DR2 are not required for recombination in vivo and in vitro. Their function is to provide resolution selectivity to the reaction by stimulating recombination between directly oriented sites on a same DNA molecule. In the absence of DR1 and/or DR2, TnpI-mediated recombination of supercoiled DNA substrates gives a mixture of topologically variable products, while deletion between two wild-type IRSs exclusively produces two-noded catenanes. This demonstrates that TnpI binding to the accessory motifs DR1 and DR2 contributes to the formation of a specific synaptic complex in which catalytically inert recombinase subunits act as architectural elements to control recombination sites pairing and strand exchange. A model for the organization of TnpI/IRS recombination complex is presented.
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Affiliation(s)
- Virginie Vanhooff
- Unité de Génétique, Institut des Sciences de la Vie, Université Catholique de Louvain, 5/6 Place Croix du Sud, B-1348 Louvain-la-Neuve, Belgium
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24
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Rowland SJ, Boocock MR, Stark WM. DNA bending in the Sin recombination synapse: functional replacement of HU by IHF. Mol Microbiol 2006; 59:1730-43. [PMID: 16553879 DOI: 10.1111/j.1365-2958.2006.05064.x] [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] [Indexed: 11/28/2022]
Abstract
The serine recombinase Sin requires a non-specific DNA-bending protein such as Hbsu for activity at its recombination site resH. Hbsu, and Sin subunits bound at site II of resH, together regulate recombination, ensuring selectivity for directly repeated resH sites by specifying assembly of an intertwined synapse. To investigate the role of the DNA-bending protein in defining the architecture of the synapse, we constructed a chimaeric recombination site (resF) which allows Hbsu to be substituted by IHF, binding specifically between site I (the crossover site) and site II. Two Sin dimers and one IHF dimer can bind together to the closely adjoining sites in resF, forming folded complexes. The precise position of the IHF site within the site I-site II spacer determines the conformation of these complexes, and also the reactivity of the resF sites in recombination assays. The data suggest that a sharp bend with a specific geometry is required in the spacer DNA, to bring the Sin dimers at sites I and II together in the correct relative orientation for synapse assembly and regulation, consistent with our model for a highly condensed synapse in which Hbsu/IHF has a purely architectural function.
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Affiliation(s)
- Sally-J Rowland
- University of Glasgow, Institute of Biomedical and Life Sciences, Division of Molecular Genetics, Anderson College, UK.
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25
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Yin Z, Harshey RM. Enhancer-independent Mu transposition from two topologically distinct synapses. Proc Natl Acad Sci U S A 2006; 102:18884-9. [PMID: 16380426 PMCID: PMC1323169 DOI: 10.1073/pnas.0506873102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transposition of Mu is strictly dependent on a specific orientation of the left (L) and right (R) ends of Mu and a distant enhancer site (E) located on supercoiled DNA. Five DNA crossings are trapped in the three-site synapse, two of which are contributed by the interwrapping of L and R. To determine the contribution of E to the interwrapping of Mu ends, we examined the topology of the LR synapse under two different enhancer-independent reaction conditions. One of these conditions, which also alleviates the requirement for a specific orientation of Mu ends, revealed two topologically distinct arrangements of the ends. In their normal relative orientation, L and R were either plectonemically interwrapped or aligned by random collision. Addition of the enhancer to this system channeled synapsis toward the interwrapped pathway. When the ends were in the wrong relative orientation, synapsis occurred exclusively by random collision. In the second enhancer-independent condition, which retains the requirement for a specific orientation of Mu ends, synapsis of L and R was entirely by interwrapping. The two distinct kinds of synapses also were identified by gel electrophoresis. We discuss these results in the context of the "topological filter" model and consider the many contributions the enhancer makes to the biologically relevant interwrapped synapse.
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Affiliation(s)
- Zhiqi Yin
- Section of Molecular Genetics and Microbiology, and Institute of Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
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26
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Akopian A, Gourlay S, James H, Colloms SD. Communication between accessory factors and the Cre recombinase at hybrid psi-loxP sites. J Mol Biol 2006; 357:1394-408. [PMID: 16487975 DOI: 10.1016/j.jmb.2006.01.050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 01/10/2006] [Accepted: 01/11/2006] [Indexed: 11/19/2022]
Abstract
By placing loxP adjacent to the accessory sequences from the Xer/psi multimer resolution system, we have imposed topological selectivity and specificity on Cre/loxP recombination. In this hybrid recombination system, the Xer accessory protein PepA binds to psi accessory sequences, interwraps them, and brings the loxP sites together such that the product of recombination is a four-node catenane. Here, we investigate communication between PepA and Cre by varying the distance between loxP and the accessory sequences, and by altering the orientation of loxP. The yield of four-node catenane and the efficiency of recombination in the presence of PepA varied with the helical phase of loxP with respect to the accessory sequences. When the orientation of loxP was reversed, or when half a helical turn was added between the accessory sequences and loxP, PepA reversed the preferred order of strand exchange by Cre at loxP. The results imply that PepA and the accessory sequences define precisely the geometry of the synapse formed by the loxP sites, and that this overcomes the innate preference of Cre to initiate recombination on the bottom strand of loxP. Further analysis of our results demonstrates that PepA can stimulate strand exchange by Cre in two distinct synaptic complexes, with the C-terminal domains of Cre facing either towards or away from PepA. Thus, no specific PepA-recombinase interaction is required, and correct juxtaposition of the loxP sites is sufficient to activate Cre in this system.
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Affiliation(s)
- Aram Akopian
- Division of Molecular Genetics, Institute of Biomedical and Life Sciences, Anderson College, University of Glasgow, 56 Dumbarton Road, Glasgow G11 6NU, Scotland, UK
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27
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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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28
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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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29
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Yin Z, Jayaram M, Pathania S, Harshey RM. The Mu Transposase Interwraps Distant DNA Sites within a Functional Transpososome in the Absence of DNA Supercoiling. J Biol Chem 2005; 280:6149-56. [PMID: 15563455 DOI: 10.1074/jbc.m411679200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A Mu transpososome assembled on negatively supercoiled DNA traps five supercoils by intertwining the left (L) and right (R) ends of Mu with an enhancer element (E). To investigate the contribution of DNA supercoiling to this elaborate synapse in which E and L cross once, E and R twice, and L and R twice, we have analyzed DNA crossings in a transpososome assembled on nicked substrates under conditions that bypass the supercoiling requirement for transposition. We find that the transposase MuA can recreate an essentially similar topology on nicked substrates, interwrapping both E-R and L-R twice but being unable to generate the single E-L crossing. In addition, we deduce that the functional MuA tetramer must contribute to three of the four observed crossings and, thus, to restraining the enhancer within the complex. We discuss the contribution of both MuA and DNA supercoiling to the 5-noded Mu synapse built at the 3-way junction.
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Affiliation(s)
- Zhiqi Yin
- Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas, Austin, TX 78712, USA
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30
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Gourlay SC, Colloms SD. Control of Cre recombination by regulatory elements from Xer recombination systems. Mol Microbiol 2004; 52:53-65. [PMID: 15049810 DOI: 10.1111/j.1365-2958.2003.03962.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Site-specific recombination by the Cre recombinase takes place at a simple DNA site (loxP), requires no additional proteins and gives topologically simple recombination products. In contrast, cer and psi sites for Xer recombination contain approximately 150 bp of accessory sequences, require accessory proteins PepA, ArgR and ArcA, and the products are specifically linked to form a four-noded catenane. Here, we use hybrid sites consisting of accessory sequences of cer or psi fused to loxP to probe the function of accessory proteins in site-specific recombination. We show that PepA instructs Cre to produce four-noded catenane, but is not required for recombination at these hybrid sites. Mutants of Cre that require PepA and accessory sequences for efficient recombination were selected. PepA-dependent Cre gave products with a specific topology and displayed resolution selectivity. Our results reveal that PepA acts autonomously in the synapsis of psi and cer accessory sequences and is the main architectural element responsible for intertwining accessory site DNA. We suggest that accessory proteins can activate recombinases simply by synapsing the regulatory DNA sequences, thus bringing the recombination sites together with a specific geometry. This may occur without the need for protein-protein interactions between accessory proteins and the recombinases.
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Affiliation(s)
- Sarah C Gourlay
- Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Anderson College, 56 Dumbarton Road, Glasgow G11 6NU, UK
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31
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Paul S, Summers D. ArgR and PepA, accessory proteins for XerCD-mediated resolution of ColE1 dimers, are also required for stable maintenance of the P1 prophage. Plasmid 2004; 52:63-8. [PMID: 15212893 DOI: 10.1016/j.plasmid.2004.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Indexed: 10/26/2022]
Abstract
Dimers of low copy number plasmids must be resolved to monomers to prevent interference with active partition. For the P1 prophage this is achieved by the Cre site-specific recombinase acting at lox. Multimerisation of multicopy plasmids threatens stability via copy number depression, and multimers of ColE1 are resolved by XerCD-mediated recombination at cer. Xer-cer is constrained to multimer resolution by accessory proteins ArgR and PepA. Recently, it has been shown that ArgR and PepA influence Cre-mediated recombination at a cer-lox hybrid site in vitro, defining the structure of the synaptic complex. We show here that both ArgR and PepA are required for stable maintenance of the P1 prophage. It is extremely difficult to establish P1 in a strain lacking PepA and the prophage was lost rapidly once selection was removed. ArgR plays a less crucial role although its absence significantly increased prophage loss. The effect of the accessory proteins is seen only at physiological concentrations of Cre; when the recombinase is expressed from a multicopy plasmid, the prophage is unstable even in the presence of ArgR and PepA. We propose that ArgR and PepA are involved in Cre-lox recombination in vivo, probably by constraining the system to resolution of prophage dimers.
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Affiliation(s)
- Sunirmal Paul
- Department of Genetics, Cambridge University, Downing Street, Cambridge CB2 3EH, UK
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32
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Burke ME, Arnold PH, He J, Wenwieser SVCT, Rowland SJ, Boocock MR, Stark WM. Activating mutations of Tn3 resolvase marking interfaces important in recombination catalysis and its regulation. Mol Microbiol 2004; 51:937-48. [PMID: 14763971 DOI: 10.1046/j.1365-2958.2003.03831.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Catalysis of DNA recombination by Tn3 resolvase is conditional on prior formation of a synapse, comprising 12 resolvase subunits and two recombination sites (res). Each res binds a resolvase dimer at site I, where strand exchange takes place, and additional dimers at two adjacent 'accessory' binding sites II and III. 'Hyperactive' resolvase mutants, that catalyse strand exchange at site I without accessory sites, were selected in E. coli. Some single mutants can resolve a res x site I plasmid (that is, with one res and one site I), but two or more activating mutations are necessary for efficient resolution of a site I x site I plasmid. Site I x site I resolution by hyperactive mutants can be further stimulated by mutations at the crystallographic 2-3' interface that abolish activity of wild-type resolvase. Activating mutations may allow regulatory mechanisms of the wild-type system to be bypassed, by stabilizing or destabilizing interfaces within and between subunits in the synapse. The positions and characteristics of the mutations support a mechanism for strand exchange by serine recombinases in which the DNA is on the outside of a recombinase tetramer, and the tertiary/quaternary structure of the tetramer is reconfigured.
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Affiliation(s)
- Mary E Burke
- Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, UK
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Jayaram M, Mehta S, Uzri D, Voziyanov Y, Velmurugan S. Site-specific recombination and partitioning systems in the stable high copy propagation of the 2-micron yeast plasmid. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2004; 77:127-72. [PMID: 15196892 DOI: 10.1016/s0079-6603(04)77004-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Makkuni Jayaram
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
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Pathania S, Jayaram M, Harshey RM. A unique right end-enhancer complex precedes synapsis of Mu ends: the enhancer is sequestered within the transpososome throughout transposition. EMBO J 2003; 22:3725-36. [PMID: 12853487 PMCID: PMC165624 DOI: 10.1093/emboj/cdg354] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Assembly of the Mu transpososome is dependent on interactions of transposase subunits with the left (L) and right (R) ends of Mu and an enhancer (E). We have followed the order and dynamics of association of these sites within a series of transpososomes prior to and during formation of a three-site complex (LER), engagement of Mu ends by the transposase active site (type 0 complex), cleavage of the ends (type I complex) and their transfer to target DNA (type II complex). LER appears to be preceded by a two-site complex (ER) where E and R are interwrapped twice, as in the mature transpososome. At each stage thereafter, the overall topology of five DNA supercoils is retained: two between E and R, one between E and L and two between L and R. However, L-R interactions within LER appear to be flexible. Unexpectedly, the enhancer was seen to persist within the transpososome through cleavage and strand transfer of Mu ends to target DNA.
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Affiliation(s)
- Shailja Pathania
- Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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35
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Grainge I, Pathania S, Vologodskii A, Harshey RM, Jayaram M. Symmetric DNA sites are functionally asymmetric within Flp and Cre site-specific DNA recombination synapses. J Mol Biol 2002; 320:515-27. [PMID: 12096907 DOI: 10.1016/s0022-2836(02)00517-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Flp and Cre-mediated recombination on symmetrized FRT and loxP sites, respectively, in circular plasmid substrates yield both DNA inversion and deletion. However, upon sequestering three negative supercoils outside the recombination complex using the resII-resIII synapse formed by Tn3 resolvase and the LER synapse formed by phage Mu transposase in the case of Flp and Cre, respectively, the reactions are channeled towards inversion at the expense of deletion. The inversion product is a trefoil, its unique topology being conferred by the external resolvase or LER synapse. Thus, Flp and Cre assign their symmetrized substrates a strictly antiparallel orientation with respect to strand cleavage and exchange. These conclusions are supported by the product profiles from tethered parallel and antiparallel native FRT sites in dilution and competition assays. Furthermore, the observed recombination bias favoring deletion over inversion in a nicked circular substrate containing two symmetrized FRT sites is consistent with the predictions from Monte Carlo simulations based on antiparallel synapsis of the DNA partners.
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Affiliation(s)
- Ian Grainge
- Section of Molecular Genetics and Microbiology and the Institute of Cell and Molecular Biology, University of Texas at Austin, 78712, USA
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36
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Pathania S, Jayaram M, Harshey RM. Path of DNA within the Mu transpososome. Transposase interactions bridging two Mu ends and the enhancer trap five DNA supercoils. Cell 2002; 109:425-36. [PMID: 12086600 DOI: 10.1016/s0092-8674(02)00728-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The phage Mu transpososome is assembled by interactions of transposase subunits with the left (L) and right (R) ends of Mu and an enhancer (E) located in between. A metastable three-site complex LER progresses into a more stable type 0 complex in which a tetrameric transposase is poised for DNA cleavage. "Difference topology" has revealed five trapped negative supercoils within type 0, three contributed by crossings of E with L and R, and two by crossings of L with R. This is the most complex DNA arrangement seen to date within a recombination synapse. Contrary to the prevailing notion, the enhancer appears not to be released immediately following type 0 assembly. Difference topology provides a simple method for determining the ordered sequestration of DNA segments within nucleoprotein assemblies.
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Affiliation(s)
- Shailja Pathania
- Section of Molecular Genetics and Microbiology and Institute of Cellular and Molecular Biology, University of Texas at Austin, 78712, USA
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37
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Rowland SJ, Stark WM, Boocock MR. Sin recombinase from Staphylococcus aureus: synaptic complex architecture and transposon targeting. Mol Microbiol 2002; 44:607-19. [PMID: 11994145 DOI: 10.1046/j.1365-2958.2002.02897.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Sin recombinase from Staphylococcus aureus builds a distinctive DNA-protein synaptic complex to regulate strand exchange. Sin binds at two sites within an 86 basepair (bp) recombination site, resH. We propose that inverted motifs at the crossover site, and tandem motifs at the regulatory site, are recognized by structurally disparate Sin dimers. An essential architectural protein, Hbsu, binds at a discrete central site in resH. Positions of Hbsu-induced DNA deformation coincide with natural targets for Tn552 integration. Remarkably, Sin has the same topological selectivity as Tn3 and gammadelta resolvases. Our model for the recombination synapse has at its core an assembly of four Sin dimers; Hbsu plays an architectural role that is taken by two resolvase dimers in models of the Tn3/gammadelta synapse.
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Affiliation(s)
- Sally-J Rowland
- Institute of Biomedical and Life Sciences, University of Glasgow, Anderson College, UK.
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38
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Abstract
Most site-specific recombinases fall into one of two families, based on evolutionary and mechanistic relatedness. These are the tyrosine recombinases or lambda integrase family and the serine recombinases or resolvase/invertase family. The tyrosine recombinases are structurally diverse and functionally versatile and include integrases, resolvases, invertases and transposases. Recent studies have revealed that the serine recombinase family is equally versatile and members have a variety of structural forms. The archetypal resolvase/invertases are highly regulated, only affect resolution or inversion and they have an N-terminal catalytic domain and a C-terminal DNA binding domain. Phage-encoded serine recombinases (e.g. phiC31 integrase) cause integration and excision with strictly controlled directionality, and have an N-terminal catalytic domain but much longer C-terminal domains compared with the resolvase/invertases. This high molecular weight group also contains transposases (e.g. TnpX from Tn4451). Other transposases, which belong to a third structurally different group, are similar in size to the resolvase/invertases but have the DNA binding domain N-terminal to the catalytic domain (e.g. IS607 transposase). These three structural groups represented by the resolvase/invertases, the large serine recombinases and relatives of IS607 transposase correlate with three major groupings seen in a phylogeny of the catalytic domains. These observations indicate that the serine recombinases are modular and that fusion of the catalytic domain to unrelated sequences has generated structural and functional diversity.
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Affiliation(s)
- Margaret C M Smith
- Institute of Genetics, Queens Medical Centre, University of Nottingham, NG7 2UH, UK.
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39
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Aussel L, Barre FX, Aroyo M, Stasiak A, Stasiak AZ, Sherratt D. FtsK Is a DNA motor protein that activates chromosome dimer resolution by switching the catalytic state of the XerC and XerD recombinases. Cell 2002; 108:195-205. [PMID: 11832210 DOI: 10.1016/s0092-8674(02)00624-4] [Citation(s) in RCA: 248] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
FtsK acts at the bacterial division septum to couple chromosome segregation with cell division. We demonstrate that a truncated FtsK derivative, FtsK(50C), uses ATP hydrolysis to translocate along duplex DNA as a multimer in vitro, consistent with FtsK having an in vivo role in pumping DNA through the closing division septum. FtsK(50C) also promotes a complete Xer recombination reaction between dif sites by switching the state of activity of the XerCD recombinases so that XerD makes the first pair of strand exchanges to form Holliday junctions that are then resolved by XerC. The reaction between directly repeated dif sites in circular DNA leads to the formation of uncatenated circles and is equivalent to the formation of chromosome monomers from dimers.
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Affiliation(s)
- Laurent Aussel
- Division of Molecular Genetics, Department of Biochemistry, University of Oxford, OX1 3QU, Oxford, United Kingdom
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40
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Abstract
Major advances in the use of site-specific recombinases to facilitate sustained gene expression via chromosomal targeting have been made during the past year. New tools for genomic manipulations using this technology include the discovery of epitopes in recombinases that confer nuclear localization, crystal structures that show the precise topology of recombinase-DNA-substrate synaptic complexes, manipulations of the DNA recognition sequences that select for integration over excision of DNA, and manipulations that make changes in gene expression inducible by drug administration. In addition, endogenous eukaryotic and mammalian DNA sequences have been discovered that can support site-specific recombinase-mediated manipulations.
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Affiliation(s)
- C Gorman
- DNA Bridges, Inc., San Francisco, CA 94117, USA.
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41
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Grainge I, Buck D, Jayaram M. Geometry of site alignment during int family recombination: antiparallel synapsis by the Flp recombinase. J Mol Biol 2000; 298:749-64. [PMID: 10801346 DOI: 10.1006/jmbi.2000.3679] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Flp site-specific recombinase functions in the copy number amplification of the yeast 2 microm plasmid. The recombination reaction is catalyzed by four monomers of Flp bound to two separate, but identical, recombination sites (FRT sites) and occurs in two sequential pairs of strand exchanges. The relative orientation of the two recombination sites during synapsis was examined. Topoisomerase relaxation and nick ligation were used to detect topological nodes introduced by the synapse prior to the chemical steps of recombination. A single negative supercoil was found to be trapped by Flp in substrates with inverted FRT sites whereas no trapped supercoils were observed with direct repeats. The topology of products resulting from Flp-mediated recombination adjacent to a well characterised synapse, that of Tn3 resolvase/res, was analyzed. The deletion and inversion reactions yielded the four noded catenane and the three noded knot, respectively, as the simplest and the most abundant products. The linking number change introduced by the Flp-mediated inversion reaction was determined to be +/-2. The most parsimonious explanation of these results is that Flp aligns its recombination sites with antiparallel geometry. The majority of synapses appear to occur without entrapment of additional random plectonemic DNA supercoils between the sites and no additional crossings are introduced as a result of the chemical steps of recombination.
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Affiliation(s)
- I Grainge
- Section of Molecular Genetics and Microbiology and The Institute for Cell and Molecular Biology, Austin, TX 78712, USA.
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