1
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Lu D, Chen B. Coordinated motion of molecular motors on DNA chains with branch topology. ACTA MECHANICA SINICA = LI XUE XUE BAO 2022; 38:621225. [PMID: 35601132 PMCID: PMC9109741 DOI: 10.1007/s10409-021-09045-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/25/2021] [Indexed: 06/15/2023]
Abstract
To understand the macroscopic mechanical behaviors of responsive DNA hydrogels integrated with DNA motors, we constructed a state map for the translocation process of a single FtsKC on a single DNA chain at the molecular level and then investigated the movement of single or multiple FtsKC motors on DNA chains with varied branch topologies. Our studies indicate that multiple FtsKC motors can have coordinated motion, which is mainly due to the force-responsive behavior of individual FtsKC motors. We further suggest the potential application of motors of FtsKC, together with DNA chains of specific branch topology, to serve as strain sensors in hydrogels.
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Affiliation(s)
- Di Lu
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310058 China
| | - Bin Chen
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310058 China
- Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Hangzhou, 310027 China
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2
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Ryu JK, Rah SH, Janissen R, Kerssemakers JWJ, Bonato A, Michieletto D, Dekker C. Condensin extrudes DNA loops in steps up to hundreds of base pairs that are generated by ATP binding events. Nucleic Acids Res 2021; 50:820-832. [PMID: 34951453 PMCID: PMC8789078 DOI: 10.1093/nar/gkab1268] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 10/22/2021] [Accepted: 12/09/2021] [Indexed: 12/28/2022] Open
Abstract
The condensin SMC protein complex organizes chromosomal structure by extruding loops of DNA. Its ATP-dependent motor mechanism remains unclear but likely involves steps associated with large conformational changes within the ∼50 nm protein complex. Here, using high-resolution magnetic tweezers, we resolve single steps in the loop extrusion process by individual yeast condensins. The measured median step sizes range between 20–40 nm at forces of 1.0–0.2 pN, respectively, comparable with the holocomplex size. These large steps show that, strikingly, condensin typically reels in DNA in very sizeable amounts with ∼200 bp on average per single extrusion step at low force, and occasionally even much larger, exceeding 500 bp per step. Using Molecular Dynamics simulations, we demonstrate that this is due to the structural flexibility of the DNA polymer at these low forces. Using ATP-binding-impaired and ATP-hydrolysis-deficient mutants, we find that ATP binding is the primary step-generating stage underlying DNA loop extrusion. We discuss our findings in terms of a scrunching model where a stepwise DNA loop extrusion is generated by an ATP-binding-induced engagement of the hinge and the globular domain of the SMC complex.
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Affiliation(s)
- Je-Kyung Ryu
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Sang-Hyun Rah
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Richard Janissen
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jacob W J Kerssemakers
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Andrea Bonato
- University of Edinburgh, SUPA, School of Physics and Astronomy, EH9 3FD, Edinburgh, UK
| | - Davide Michieletto
- University of Edinburgh, SUPA, School of Physics and Astronomy, EH9 3FD, Edinburgh, UK.,MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
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3
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Jean NL, Rutherford TJ, Löwe J. FtsK in motion reveals its mechanism for double-stranded DNA translocation. Proc Natl Acad Sci U S A 2020; 117:14202-14208. [PMID: 32513722 PMCID: PMC7321959 DOI: 10.1073/pnas.2001324117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
FtsK protein contains a fast DNA motor that is involved in bacterial chromosome dimer resolution. During cell division, FtsK translocates double-stranded DNA until both dif recombination sites are placed at mid cell for subsequent dimer resolution. Here, we solved the 3.6-Å resolution electron cryo-microscopy structure of the motor domain of FtsK while translocating on its DNA substrate. Each subunit of the homo-hexameric ring adopts a unique conformation and one of three nucleotide states. Two DNA-binding loops within four subunits form a pair of spiral staircases within the ring, interacting with the two DNA strands. This suggests that simultaneous conformational changes in all ATPase domains at each catalytic step generate movement through a mechanism related to filament treadmilling. While the ring is only rotating around the DNA slowly, it is instead the conformational states that rotate around the ring as the DNA substrate is pushed through.
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Affiliation(s)
- Nicolas L Jean
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Trevor J Rutherford
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Jan Löwe
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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4
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Mohapatra S, Lin CT, Feng XA, Basu A, Ha T. Single-Molecule Analysis and Engineering of DNA Motors. Chem Rev 2019; 120:36-78. [DOI: 10.1021/acs.chemrev.9b00361] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
| | | | | | | | - Taekjip Ha
- Howard Hughes Medical Institute, Baltimore, Maryland 21205, United States
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5
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Abstract
Protein complexes built of structural maintenance of chromosomes (SMC) and kleisin subunits, including cohesin, condensin and the Smc5/6 complex, are master organizers of genome architecture in all kingdoms of life. How these large ring-shaped molecular machines use the energy of ATP hydrolysis to change the topology of chromatin fibers has remained a central unresolved question of chromosome biology. A currently emerging concept suggests that the common principle that underlies the essential functions of SMC protein complexes in the control of gene expression, chromosome segregation or DNA damage repair is their ability to expand DNA into large loop structures. Here, we review the current knowledge about the biochemical and structural properties of SMC protein complexes that might enable them to extrude DNA loops and compare their action to other motor proteins and nucleic acid translocases. We evaluate the currently predominant models of active loop extrusion and propose a detailed version of a 'scrunching' model, which reconciles much of the available mechanistic data and provides an elegant explanation for how SMC protein complexes fulfill an array of seemingly diverse tasks during the organization of genomes.
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6
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Amado E, Muth G, Arechaga I, Cabezón E. The FtsK-like motor TraB is a DNA-dependent ATPase that forms higher-order assemblies. J Biol Chem 2019; 294:5050-5059. [PMID: 30723158 DOI: 10.1074/jbc.ra119.007459] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/01/2019] [Indexed: 11/06/2022] Open
Abstract
TraB is an FtsK-like DNA translocase responsible for conjugative plasmid transfer in mycelial Streptomyces Unlike other conjugative systems, which depend on a type IV secretion system, Streptomyces requires only TraB protein to transfer the plasmid as dsDNA. The γ-domain of this protein specifically binds to repeated 8-bp motifs on the plasmid sequence, following a mechanism that is reminiscent of the FtsK/SpoIIIE chromosome segregation system. In this work, we purified and characterized the enzymatic activity of TraB, revealing that it is a DNA-dependent ATPase that is highly stimulated by dsDNA substrates. Interestingly, we found that unlike the SpoIIIE protein, the γ-domain of TraB does not confer sequence-specific ATPase stimulation. We also found that TraB binds G-quadruplex DNA structures with higher affinity than TraB-recognition sequences (TRSs). An EM-based structural analysis revealed that TraB tends to assemble as large complexes comprising four TraB hexamers, which might be a prerequisite for DNA translocation across cell membranes. In summary, our findings shed light on the molecular mechanism used by the DNA-translocating motor TraB, which may be shared by other membrane-associated machineries involved in DNA binding and translocation.
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Affiliation(s)
- Eric Amado
- From the Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, Santander, Spain and
| | - Günther Muth
- Interfakultaeres Institut für Mikrobiologie und Infektionsmedizin Tuebingen IMIT, Mikrobiologie/Biotechnologie, Eberhard Karls Universitaet Tuebingen, 72074 Tuebingen, Germany
| | - Ignacio Arechaga
- From the Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, Santander, Spain and
| | - Elena Cabezón
- From the Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, Santander, Spain and
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7
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Sequence-dependent catalytic regulation of the SpoIIIE motor activity ensures directionality of DNA translocation. Sci Rep 2018; 8:5254. [PMID: 29588476 PMCID: PMC5869595 DOI: 10.1038/s41598-018-23400-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 03/09/2018] [Indexed: 12/02/2022] Open
Abstract
Transport of cellular cargo by molecular motors requires directionality to ensure proper biological functioning. During sporulation in Bacillus subtilis, directionality of chromosome transport is mediated by the interaction between the membrane-bound DNA translocase SpoIIIE and specific octameric sequences (SRS). Whether SRS regulate directionality by recruiting and orienting SpoIIIE or by simply catalyzing its translocation activity is still unclear. By using atomic force microscopy and single-round fast kinetics translocation assays we determined the localization and dynamics of diffusing and translocating SpoIIIE complexes on DNA with or without SRS. Our findings combined with mathematical modelling revealed that SpoIIIE directionality is not regulated by protein recruitment to SRS but rather by a fine-tuned balance among the rates governing SpoIIIE-DNA interactions and the probability of starting translocation modulated by SRS. Additionally, we found that SpoIIIE can start translocation from non-specific DNA, providing an alternative active search mechanism for SRS located beyond the exploratory length defined by 1D diffusion. These findings are relevant in vivo in the context of chromosome transport through an open channel, where SpoIIIE can rapidly explore DNA while directionality is modulated by the probability of translocation initiation upon interaction with SRS versus non-specific DNA.
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8
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Liu N, Chistol G, Cui Y, Bustamante C. Mechanochemical coupling and bi-phasic force-velocity dependence in the ultra-fast ring ATPase SpoIIIE. eLife 2018; 7:32354. [PMID: 29504934 PMCID: PMC5858925 DOI: 10.7554/elife.32354] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 03/03/2018] [Indexed: 11/22/2022] Open
Abstract
Multi-subunit ring-shaped ATPases are molecular motors that harness chemical free energy to perform vital mechanical tasks such as polypeptide translocation, DNA unwinding, and chromosome segregation. Previously we reported the intersubunit coordination and stepping behavior of the hexameric ring-shaped ATPase SpoIIIE (Liu et al., 2015). Here we use optical tweezers to characterize the motor’s mechanochemistry. Analysis of the motor response to external force at various nucleotide concentrations identifies phosphate release as the likely force-generating step. Analysis of SpoIIIE pausing indicates that pauses are off-pathway events. Characterization of SpoIIIE slipping behavior reveals that individual motor subunits engage DNA upon ATP binding. Furthermore, we find that SpoIIIE’s velocity exhibits an intriguing bi-phasic dependence on force. We hypothesize that this behavior is an adaptation of ultra-fast motors tasked with translocating DNA from which they must also remove DNA-bound protein roadblocks. Based on these results, we formulate a comprehensive mechanochemical model for SpoIIIE.
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Affiliation(s)
- Ninning Liu
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Gheorghe Chistol
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, Berkeley, United States.,Department of Physics, University of California, Berkeley, Berkeley, United States
| | - Yuanbo Cui
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Carlos Bustamante
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Department of Physics, University of California, Berkeley, Berkeley, United States.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, United States.,Department of Chemistry and Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.,Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, United States
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9
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Toliusis P, Zaremba M, Silanskas A, Szczelkun MD, Siksnys V. CgII cleaves DNA using a mechanism distinct from other ATP-dependent restriction endonucleases. Nucleic Acids Res 2017; 45:8435-8447. [PMID: 28854738 PMCID: PMC5737866 DOI: 10.1093/nar/gkx580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 06/28/2017] [Indexed: 01/10/2023] Open
Abstract
The restriction endonuclease CglI from Corynebacterium glutamicum recognizes an asymmetric 5′-GCCGC-3′ site and cleaves the DNA 7 and 6/7 nucleotides downstream on the top and bottom DNA strands, respectively, in an NTP-hydrolysis dependent reaction. CglI is composed of two different proteins: an endonuclease (R.CglI) and a DEAD-family helicase-like ATPase (H.CglI). These subunits form a heterotetrameric complex with R2H2 stoichiometry. However, the R2H2·CglI complex has only one nuclease active site sufficient to cut one DNA strand suggesting that two complexes are required to introduce a double strand break. Here, we report studies to evaluate the DNA cleavage mechanism of CglI. Using one- and two-site circular DNA substrates we show that CglI does not require two sites on the same DNA for optimal catalytic activity. However, one-site linear DNA is a poor substrate, supporting a mechanism where CglI complexes must communicate along the one-dimensional DNA contour before cleavage is activated. Based on experimental data, we propose that adenosine triphosphate (ATP) hydrolysis by CglI produces translocation on DNA preferentially in a downstream direction from the target, although upstream translocation is also possible. Our results are consistent with a mechanism of CglI action that is distinct from that of other ATP-dependent restriction-modification enzymes.
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Affiliation(s)
- Paulius Toliusis
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257, Vilnius, Lithuania
| | - Mindaugas Zaremba
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257, Vilnius, Lithuania
| | - Arunas Silanskas
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257, Vilnius, Lithuania
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, BS8 1TD, UK
| | - Virginijus Siksnys
- Department of Protein-DNA Interactions, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, LT-10257, Vilnius, Lithuania
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10
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Castillo F, Benmohamed A, Szatmari G. Xer Site Specific Recombination: Double and Single Recombinase Systems. Front Microbiol 2017; 8:453. [PMID: 28373867 PMCID: PMC5357621 DOI: 10.3389/fmicb.2017.00453] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/03/2017] [Indexed: 12/20/2022] Open
Abstract
The separation and segregation of newly replicated bacterial chromosomes can be constrained by the formation of circular chromosome dimers caused by crossing over during homologous recombination events. In Escherichia coli and most bacteria, dimers are resolved to monomers by site-specific recombination, a process performed by two Chromosomally Encoded tyrosine Recombinases (XerC and XerD). XerCD recombinases act at a 28 bp recombination site dif, which is located at the replication terminus region of the chromosome. The septal protein FtsK controls the initiation of the dimer resolution reaction, so that recombination occurs at the right time (immediately prior to cell division) and at the right place (cell division septum). XerCD and FtsK have been detected in nearly all sequenced eubacterial genomes including Proteobacteria, Archaea, and Firmicutes. However, in Streptococci and Lactococci, an alternative system has been found, composed of a single recombinase (XerS) genetically linked to an atypical 31 bp recombination site (difSL). A similar recombination system has also been found in 𝜀-proteobacteria such as Campylobacter and Helicobacter, where a single recombinase (XerH) acts at a resolution site called difH. Most Archaea contain a recombinase called XerA that acts on a highly conserved 28 bp sequence dif, which appears to act independently of FtsK. Additionally, several mobile elements have been found to exploit the dif/Xer system to integrate their genomes into the host chromosome in Vibrio cholerae, Neisseria gonorrhoeae, and Enterobacter cloacae. This review highlights the versatility of dif/Xer recombinase systems in prokaryotes and summarizes our current understanding of homologs of dif/Xer machineries.
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Affiliation(s)
- Fabio Castillo
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, MontréalQC, Canada
| | | | - George Szatmari
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, MontréalQC, Canada
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11
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Sherratt DJ. Chromosome stitch-up? Science 2017; 355:460-461. [PMID: 28154037 DOI: 10.1126/science.aam7183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- David J Sherratt
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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12
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Conjugative DNA-transfer in Streptomyces, a mycelial organism. Plasmid 2016; 87-88:1-9. [PMID: 27687731 DOI: 10.1016/j.plasmid.2016.09.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/13/2016] [Accepted: 09/25/2016] [Indexed: 02/06/2023]
Abstract
Conjugative DNA-transfer in the Gram-positive mycelial soil bacterium Streptomyces, well known for the production of numerous antibiotics, is a unique process involving the transfer of a double-stranded DNA molecule. Apparently it does not depend on a type IV secretion system but resembles the segregation of chromosomes during bacterial cell division. A single plasmid-encoded protein, TraB, directs the transfer from the plasmid-carrying donor to the recipient. TraB is a FtsK-like DNA-translocase, which recognizes a specific plasmid sequence, clt, via interaction with specific 8-bp repeats. Chromosomal markers are mobilized by the recognition of clt-like sequences randomly distributed all over the Streptomyces chromosomes. Fluorescence microcopy with conjugative reporter plasmids and differentially labelled recipient strains revealed conjugative plasmid transfer at the lateral walls of the hyphae, when getting in contact. Subsequently, the newly transferred plasmids cross septal cross walls, which occur at irregular distances in the mycelium and invade the neighboring compartments, thus efficiently colonizing the recipient mycelium. This intramycelial plasmid spreading requires the DNA-translocase TraB and a complex of several Spd proteins. Inactivation of a single spd gene interferes with intramycelial plasmid spreading. The molecular function of the Spd proteins is widely unknown. Spd proteins of different plasmids are highly diverse, none showing sequence similarity to a functionally characterized protein. The integral membrane protein SpdB2 binds DNA, peptidoglycan and forms membrane pores in vivo and in vitro. Intramycelial plasmid spreading is an adaptation to the mycelial growth characteristics of Streptomyces and ensures the rapid dissemination of the plasmid within the recipient colony before the onset of sporulation.
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13
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FtsK translocation permits discrimination between an endogenous and an imported Xer/dif recombination complex. Proc Natl Acad Sci U S A 2016; 113:7882-7. [PMID: 27317749 DOI: 10.1073/pnas.1523178113] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In bacteria, the FtsK/Xer/dif (chromosome dimer resolution site) system is essential for faithful vertical genetic transmission, ensuring the resolution of chromosome dimers during their segregation to daughter cells. This system is also targeted by mobile genetic elements that integrate into chromosomal dif sites. A central question is thus how Xer/dif recombination is tuned to both act in chromosome segregation and stably maintain mobile elements. To explore this question, we focused on pathogenic Neisseria species harboring a genomic island in their dif sites. We show that the FtsK DNA translocase acts differentially at the recombination sites flanking the genomic island. It stops at one Xer/dif complex, activating recombination, but it does not stop on the other site, thus dismantling it. FtsK translocation thus permits cis discrimination between an endogenous and an imported Xer/dif recombination complex.
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14
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Abstract
One of the disadvantages of circular plasmids and chromosomes is their high sensitivity to rearrangements caused by homologous recombination. Odd numbers of crossing-over occurring during or after replication of a circular replicon result in the formation of a dimeric molecule in which the two copies of the replicon are fused. If they are not converted back to monomers, the dimers of replicons may fail to correctly segregate at the time of cell division. Resolution of multimeric forms of circular plasmids and chromosomes is mediated by site-specific recombination, and the enzymes that catalyze this type of reaction fall into two families of proteins: the serine and tyrosine recombinase families. Here we give an overview of the variety of site-specific resolution systems found on circular plasmids and chromosomes.
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15
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Liu N, Chistol G, Bustamante C. Two-subunit DNA escort mechanism and inactive subunit bypass in an ultra-fast ring ATPase. eLife 2015; 4. [PMID: 26452092 PMCID: PMC4728128 DOI: 10.7554/elife.09224] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 10/08/2015] [Indexed: 11/17/2022] Open
Abstract
SpoIIIE is a homo-hexameric dsDNA translocase responsible for completing chromosome segregation in Bacillus subtilis. Here, we use a single-molecule approach to monitor SpoIIIE translocation when challenged with neutral-backbone DNA and non-hydrolyzable ATP analogs. We show that SpoIIIE makes multiple essential contacts with phosphates on the 5'→3' strand in the direction of translocation. Using DNA constructs with two neutral-backbone segments separated by a single charged base pair, we deduce that SpoIIIE’s step size is 2 bp. Finally, experiments with non-hydrolyzable ATP analogs suggest that SpoIIIE can operate with non-consecutive inactive subunits. We propose a two-subunit escort translocation mechanism that is strict enough to enable SpoIIIE to track one DNA strand, yet sufficiently compliant to permit the motor to bypass inactive subunits without arrest. We speculate that such a flexible mechanism arose for motors that, like SpoIIIE, constitute functional bottlenecks where the inactivation of even a single motor can be lethal for the cell. DOI:http://dx.doi.org/10.7554/eLife.09224.001 Bacillus subtilis is a bacterium that lives in the soil. When food is in short supply, B. subtilis stops reproducing and individual bacterial cells transform into spores that lay dormant until conditions improve. While, B subtilis is generally harmless, it forms spores in a similar way to other bacteria that cause diseases such as anthrax. During spore formation, a membrane forms to divide the cell into a large mother cell and a smaller “forespore” cell. Then, a copy of the mother cell’s DNA – which is made of building blocks called bases – moves into the forespore. A group of proteins called SpoIIIE is instrumental in this process as it uses energy from a molecule called ATP to pump the DNA across the membrane at the rapid speed of 5,000 base pairs of DNA per second. SpoIIIE contains six individual protein subunits that form a ring-shaped motor structure that spans the membrane. It belongs to a large family of proteins that are found in all living organisms and drive many vital processes. How does SpoIIIE interact with DNA and how do the individual subunits coordinate their behaviour? Liu, Chistol et al. address these questions by using instruments called optical tweezers, which use a laser beam to hold and manipulate tiny objects. The experiments show that to move a fragment of DNA across a membrane, SpoIIIE only makes contact with one of the two strands that make up the DNA molecule. The experiments suggest that the DNA is handed over from one SpoIIIE subunit to another in a sequential order. This would allow the DNA to remain bound to SpoIIIE at all times as it passes through the membrane. Next, Liu, Chistol et al. measured how SpoIIIE steps along the DNA and found that each subunit takes a small two base pair step when energy is released from a single molecule of ATP. There is an element of flexibility in the system, because SpoIIIE can still move DNA normally even if some subunits cannot use energy from ATP. This provides a fail-safe mechanism that still allows the cells to form spores in the event that one subunit is disabled. Future work will concentrate in understanding how the subunits communicate around the ring to coordinate their sequential use of ATP and their DNA pumping activity. DOI:http://dx.doi.org/10.7554/eLife.09224.002
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Affiliation(s)
- Ninning Liu
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, United States
| | - Gheorghe Chistol
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, United States.,Department of Physics, University of California, Berkeley, United States
| | - Carlos Bustamante
- Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, United States.,Department of Physics, University of California, Berkeley, United States.,California Institute for Quantitative Biosciences, Berkeley, United States.,Department of Chemistry, Howard Hughes Medical Institute, University of California, Berkeley, United States.,Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Kavli Energy NanoSciences Institute at the University of California, Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, United States
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16
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Assembly, translocation, and activation of XerCD-dif recombination by FtsK translocase analyzed in real-time by FRET and two-color tethered fluorophore motion. Proc Natl Acad Sci U S A 2015; 112:E5133-41. [PMID: 26324908 DOI: 10.1073/pnas.1510814112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The FtsK dsDNA translocase functions in bacterial chromosome unlinking by activating XerCD-dif recombination in the replication terminus region. To analyze FtsK assembly and translocation, and the subsequent activation of XerCD-dif recombination, we extended the tethered fluorophore motion technique, using two spectrally distinct fluorophores to monitor two effective lengths along the same tethered DNA molecule. We observed that FtsK assembled stepwise on DNA into a single hexamer, and began translocation rapidly (∼ 0.25 s). Without extruding DNA loops, single FtsK hexamers approached XerCD-dif and resided there for ∼ 0.5 s irrespective of whether XerCD-dif was synapsed or unsynapsed. FtsK then dissociated, rather than reversing. Infrequently, FtsK activated XerCD-dif recombination when it encountered a preformed synaptic complex, and dissociated before the completion of recombination, consistent with each FtsK-XerCD-dif encounter activating only one round of recombination.
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17
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Crozat E, Rousseau P, Fournes F, Cornet F. The FtsK family of DNA translocases finds the ends of circles. J Mol Microbiol Biotechnol 2015; 24:396-408. [PMID: 25732341 DOI: 10.1159/000369213] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A global view of bacterial chromosome choreography during the cell cycle is emerging, highlighting as a next challenge the description of the molecular mechanisms and factors involved. Here, we review one such factor, the FtsK family of DNA translocases. FtsK is a powerful and fast translocase that reads chromosome polarity. It couples segregation of the chromosome with cell division and controls the last steps of segregation in time and space. The second model protein of the family SpoIIIE acts in the transfer of the Bacillus subtilis chromosome during sporulation. This review focuses on the molecular mechanisms used by FtsK and SpoIIIE to segregate chromosomes with emphasis on the latest advances and open questions.
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Affiliation(s)
- Estelle Crozat
- Laboratoire de Microbiologie et de Génétique Moléculaires, CNRS, and Université de Toulouse, Université Paul Sabatier, Toulouse, France
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18
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Common mechanisms of DNA translocation motors in bacteria and viruses using one-way revolution mechanism without rotation. Biotechnol Adv 2015; 32:853-72. [PMID: 24913057 DOI: 10.1016/j.biotechadv.2014.01.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 01/24/2014] [Accepted: 01/25/2014] [Indexed: 12/15/2022]
Abstract
Biomotors were once described into two categories: linear motor and rotation motor. Recently, a third type of biomotor with revolution mechanism without rotation has been discovered. By analogy, rotation resembles the Earth rotating on its axis in a complete cycle every 24h, while revolution resembles the Earth revolving around the Sun one circle per 365 days (see animations http://nanobio.uky.edu/movie.html). The action of revolution that enables a motor free of coiling and torque has solved many puzzles and debates that have occurred throughout the history of viral DNA packaging motor studies. It also settles the discrepancies concerning the structure, stoichiometry, and functioning of DNA translocation motors. This review uses bacteriophages Phi29, HK97, SPP1, P22, T4, and T7 as well as bacterial DNA translocase FtsK and SpoIIIE or the large eukaryotic dsDNA viruses such as mimivirus and vaccinia virus as examples to elucidate the puzzles. These motors use ATPase, some of which have been confirmed to be a hexamer, to revolve around the dsDNA sequentially. ATP binding induces conformational change and possibly an entropy alteration in ATPase to a high affinity toward dsDNA; but ATP hydrolysis triggers another entropic and conformational change in ATPase to a low affinity for DNA, by which dsDNA is pushed toward an adjacent ATPase subunit. The rotation and revolution mechanisms can be distinguished by the size of channel: the channels of rotation motors are equal to or smaller than 2 nm, that is the size of dsDNA, whereas channels of revolution motors are larger than 3 nm. Rotation motors use parallel threads to operate with a right-handed channel, while revolution motors use a left-handed channel to drive the right-handed DNA in an anti-chiral arrangement. Coordination of several vector factors in the same direction makes viral DNA-packaging motors unusually powerful and effective. Revolution mechanism that avoids DNA coiling in translocating the lengthy genomic dsDNA helix could be advantageous for cell replication such as bacterial binary fission and cell mitosis without the need for topoisomerase or helicase to consume additional energy.
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19
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Liu S, Chistol G, Bustamante C. Mechanical operation and intersubunit coordination of ring-shaped molecular motors: insights from single-molecule studies. Biophys J 2014; 106:1844-58. [PMID: 24806916 DOI: 10.1016/j.bpj.2014.03.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/19/2014] [Indexed: 01/27/2023] Open
Abstract
Ring NTPases represent a large and diverse group of proteins that couple their nucleotide hydrolysis activity to a mechanical task involving force generation and some type of transport process in the cell. Because of their shape, these enzymes often operate as gates that separate distinct cellular compartments to control and regulate the passage of chemical species across them. In this manner, ions and small molecules are moved across membranes, biopolymer substrates are segregated between cells or moved into confined spaces, double-stranded nucleic acids are separated into single strands to provide access to the genetic information, and polypeptides are unfolded and processed for recycling. Here we review the recent advances in the characterization of these motors using single-molecule manipulation and detection approaches. We describe the various mechanisms by which ring motors convert chemical energy to mechanical force or torque and coordinate the activities of individual subunits that constitute the ring. We also examine how single-molecule studies have contributed to a better understanding of the structural elements involved in motor-substrate interaction, mechanochemical coupling, and intersubunit coordination. Finally, we discuss how these molecular motors tailor their operation-often through regulation by other cofactors-to suit their unique biological functions.
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Affiliation(s)
- Shixin Liu
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; California Institute for Quantitative Biosciences, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California
| | - Gheorghe Chistol
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Physics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California
| | - Carlos Bustamante
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; California Institute for Quantitative Biosciences, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Physics, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California; Department of Molecular and Cell Biology, Department of Chemistry, Howard Hughes Medical Institute, and Kavli Energy NanoSciences Institute, University of California, Berkeley, and Lawrence Berkeley National Laboratory, Berkeley, California.
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20
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Besprozvannaya M, Burton BM. Do the same traffic rules apply? Directional chromosome segregation by SpoIIIE and FtsK. Mol Microbiol 2014; 93:599-608. [PMID: 25040776 DOI: 10.1111/mmi.12708] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2014] [Indexed: 11/28/2022]
Abstract
Over a decade of studies have tackled the question of how FtsK/SpoIIIE translocases establish and maintain directional DNA translocation during chromosome segregation in bacteria. FtsK/SpoIIIE translocases move DNA in a highly processive, directional manner, where directionality is facilitated by sequences on the substrate DNA molecules that are being transported. In recent years, structural, biochemical, single-molecule and high-resolution microscopic studies have provided new insight into the mechanistic details of directional DNA segregation. Out of this body of work, a series of models have emerged and, ultimately, yielded two seemingly opposing models: the loading model and the target search model. We review these recent mechanistic insights into directional DNA movement and discuss the data that may serve to unite these suggested models, as well as propose future directions that may ultimately solve the debate.
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Affiliation(s)
- Marina Besprozvannaya
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA, 02138, USA
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21
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Lee JY, Finkelstein IJ, Arciszewska LK, Sherratt DJ, Greene EC. Single-molecule imaging of FtsK translocation reveals mechanistic features of protein-protein collisions on DNA. Mol Cell 2014; 54:832-43. [PMID: 24768536 PMCID: PMC4048639 DOI: 10.1016/j.molcel.2014.03.033] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 02/06/2014] [Accepted: 03/14/2014] [Indexed: 11/21/2022]
Abstract
In physiological settings, DNA translocases will encounter DNA-bound proteins, which must be dislodged or bypassed to allow continued translocation. FtsK is a bacterial translocase that promotes chromosome dimer resolution and decatenation by activating XerCD-dif recombination. To better understand how translocases act in crowded environments, we used single-molecule imaging to visualize FtsK in real time as it collided with other proteins. We show that FtsK can push, evict, and even bypass DNA-bound proteins. The primary factor dictating the outcome of collisions was the relative affinity of the proteins for their specific binding sites. Importantly, protein-protein interactions between FtsK and XerD help prevent removal of XerCD from DNA by promoting rapid reversal of FtsK. Finally, we demonstrate that RecBCD always overwhelms FtsK when these two motor proteins collide while traveling along the same DNA molecule, indicating that RecBCD is capable of exerting a much greater force than FtsK when translocating along DNA.
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Affiliation(s)
- Ja Yil Lee
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Ilya J Finkelstein
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Lidia K Arciszewska
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - David J Sherratt
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA.
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22
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Mechanistic study of classical translocation-dead SpoIIIE36 reveals the functional importance of the hinge within the SpoIIIE motor. J Bacteriol 2014; 196:2481-90. [PMID: 24769697 DOI: 10.1128/jb.01725-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SpoIIIE/FtsK ATPases are central players in bacterial chromosome segregation. It remains unclear how these DNA translocases harness chemical energy (ATP turnover) to perform mechanical work (DNA movement). Bacillus subtilis sporulation provides a dramatic example of intercompartmental DNA transport, in which SpoIIIE moves 70% of the chromosome across the division plane. To understand the mechanistic requirements for DNA translocation, we investigated the DNA translocation defect of a classical nontranslocating allele, spoIIIE36. We found that the translocation phenotype is caused by a single substitution, a change of valine to methionine at position 429 (V429M), within the motor of SpoIIIE. This substitution is located at the base of a hinge between the RecA-like β domain and the α domain, which is a domain unique to the SpoIIIE/FtsK family and currently has no known function. V429M interferes with both protein-DNA interactions and oligomer assembly. These mechanistic defects disrupt coordination between ATP turnover and DNA interaction, effectively uncoupling ATP hydrolysis from DNA movement. Our data provide the first functional evidence for the importance of the hinge in DNA translocation.
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23
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O'Shea VL, Berger JM. Loading strategies of ring-shaped nucleic acid translocases and helicases. Curr Opin Struct Biol 2014; 25:16-24. [PMID: 24878340 PMCID: PMC4040187 DOI: 10.1016/j.sbi.2013.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 11/18/2013] [Accepted: 11/19/2013] [Indexed: 12/16/2022]
Abstract
Ring-shaped nucleic acid translocases and helicases catalyze the directed and processive movement of nucleic acid strands to support essential transactions such as replication, transcription, and chromosome partitioning. Assembled typically as hexamers, ring helicase/translocase systems use coordinated cycles of nucleoside triphosphate (NTP) hydrolysis to translocate extended DNA or RNA substrates through a central pore. Ring formation presents a topological challenge to the engagement of substrate oligonucleotides, and is frequently overcome by distinct loading strategies for shepherding specific motors onto their respective substrates. Recent structural studies that capture different loading intermediates have begun to reveal how different helicase/translocase rings either assemble around substrates or crack open to allow DNA or RNA strand entry, and how dedicated chaperones facilitate these events in some instances. Both prevailing mechanistic models and remaining knowledge gaps are discussed.
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Affiliation(s)
- Valerie L O'Shea
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA
| | - James M Berger
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94705, USA.
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24
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Silverstein TD, Gibb B, Greene EC. Visualizing protein movement on DNA at the single-molecule level using DNA curtains. DNA Repair (Amst) 2014; 20:94-109. [PMID: 24598576 DOI: 10.1016/j.dnarep.2014.02.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 02/01/2014] [Accepted: 02/03/2014] [Indexed: 11/18/2022]
Abstract
A fundamental feature of many nucleic-acid binding proteins is their ability to move along DNA either by diffusion-based mechanisms or by ATP-hydrolysis driven translocation. For example, most site-specific DNA-binding proteins must diffuse to some extent along DNA to either find their target sites, or to otherwise fulfill their biological roles. Similarly, nucleic-acid translocases such as helicases and polymerases must move along DNA to fulfill their functions. In both instances, the proteins must also be capable of moving in crowded environments while navigating through DNA-bound obstacles. These types of behaviors can be challenging to analyze by bulk biochemical methods because of the transient nature of the interactions, and/or heterogeneity of the reaction intermediates. The advent of single-molecule methodologies has overcome some of these problems, and has led to many new insights into the mechanisms that contribute to protein motion along DNA. We have developed DNA curtains as a tool to facilitate single molecule observations of protein-nucleic acid interactions, and we have applied these new research tools to systems involving both diffusive-based motion as well as ATP directed translocation. Here we highlight these studies by first discussing how diffusion contributes to target searches by proteins involved in post-replicative mismatch repair. We then discuss DNA curtain assays of two different DNA translocases, RecBCD and FtsK, which participate in homologous DNA recombination and site-specific DNA recombination, respectively.
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Affiliation(s)
- Timothy D Silverstein
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA
| | - Bryan Gibb
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA
| | - Eric C Greene
- Department of Biochemistry & Molecular Biophysics, Columbia University, New York, NY, USA; Howard Hughes Medical Institute, USA.
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25
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Cattoni DI, Thakur S, Godefroy C, Le Gall A, Lai-Kee-Him J, Milhiet PE, Bron P, Nöllmann M. Structure and DNA-binding properties of the Bacillus subtilis SpoIIIE DNA translocase revealed by single-molecule and electron microscopies. Nucleic Acids Res 2013; 42:2624-36. [PMID: 24297254 PMCID: PMC3936747 DOI: 10.1093/nar/gkt1231] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
SpoIIIE/FtsK are a family of ring-shaped, membrane-anchored, ATP-fuelled motors required to segregate DNA across bacterial membranes. This process is directional and requires that SpoIIIE/FtsK recognize highly skewed octameric sequences (SRS/KOPS for SpoIIIE/FtsK) distributed along the chromosome. Two models have been proposed to explain the mechanism by which SpoIIIE/FtsK interact with DNA. The loading model proposes that SpoIIIE/FtsK oligomerize exclusively on SpoIIIE recognition sequence/orienting polar sequences (SRS/KOPS) to accomplish directional DNA translocation, whereas the target search and activation mechanism proposes that pre-assembled SpoIIIE/FtsK hexamers bind to non-specific DNA, reach SRS/KOPS by diffusion/3d hopping and activate at SRS/KOPS. Here, we employ single-molecule total internal reflection imaging, atomic force and electron microscopies and ensemble biochemical methods to test these predictions and obtain further insight into the SpoIIIE–DNA mechanism of interaction. First, we find that SpoIIIE binds DNA as a homo-hexamer with neither ATP binding nor hydrolysis affecting the binding mechanism or affinity. Second, we show that hexameric SpoIIIE directly binds to double-stranded DNA without requiring the presence of SRS or free DNA ends. Finally, we find that SpoIIIE hexamers can show open and closed conformations in solution, with open-ring conformations most likely resembling a state poised to load to non-specific, double-stranded DNA. These results suggest how SpoIIIE and related ring-shaped motors may be split open to bind topologically closed DNA.
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Affiliation(s)
- Diego I Cattoni
- Centre de Biochimie Structurale, Department of Single-Molecule Biophysics CNRS UMR5048, INSERM U554, Université de Montpellier I & II, 29 rue de Navacelles, 34090 Montpellier, France
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26
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Diagne CT, Salhi M, Crozat E, Salomé L, Cornet F, Rousseau P, Tardin C. TPM analyses reveal that FtsK contributes both to the assembly and the activation of the XerCD-dif recombination synapse. Nucleic Acids Res 2013; 42:1721-32. [PMID: 24214995 PMCID: PMC3919580 DOI: 10.1093/nar/gkt1024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Circular chromosomes can form dimers during replication and failure to resolve those into monomers prevents chromosome segregation, which leads to cell death. Dimer resolution is catalysed by a highly conserved site-specific recombination system, called XerCD-dif in Escherichia coli. Recombination is activated by the DNA translocase FtsK, which is associated with the division septum, and is thought to contribute to the assembly of the XerCD-dif synapse. In our study, direct observation of the assembly of the XerCD-dif synapse, which had previously eluded other methods, was made possible by the use of Tethered Particle Motion, a single molecule approach. We show that XerC, XerD and two dif sites suffice for the assembly of XerCD-dif synapses in absence of FtsK, but lead to inactive XerCD-dif synapses. We also show that the presence of the γ domain of FtsK increases the rate of synapse formation and convert them into active synapses where recombination occurs. Our results represent the first direct observation of the formation of the XerCD-dif recombination synapse and its activation by FtsK.
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Affiliation(s)
- Cheikh Tidiane Diagne
- CNRS; IPBS (Institut de Pharmacologie et de Biologie Structurale); 205 route de Narbonne BP 64182, F-31077 Toulouse, France, Université de Toulouse; UPS; IPBS; F-31077 Toulouse, France, Université de Toulouse; UPS; LMGM (Laboratoire de Microbiologie et Génétique Moléculaires); F-31062 Toulouse, France and CNRS; LMGM; F-31062 Toulouse, France
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27
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Besprozvannaya M, Pivorunas VL, Feldman Z, Burton BM. SpoIIIE protein achieves directional DNA translocation through allosteric regulation of ATPase activity by an accessory domain. J Biol Chem 2013; 288:28962-74. [PMID: 23974211 DOI: 10.1074/jbc.m113.484055] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial chromosome segregation utilizes highly conserved directional translocases of the SpoIIIE/FtsK family. These proteins employ an accessory DNA-binding domain (γ) to dictate directionality of DNA transport. It remains unclear how the interaction of γ with specific recognition sequences coordinates directional DNA translocation. We demonstrate that the γ domain of SpoIIIE inhibits ATPase activity of the motor domain in the absence of DNA but stimulates ATPase activity through sequence-specific DNA recognition. Furthermore, we observe that communication between γ subunits is necessary for both regulatory roles. Consistent with these findings, the γ domain is necessary for robust DNA transport along the length of the chromosome in vivo. Together, our data reveal that directional activation involves allosteric regulation of ATP turnover through coordinated action of γ domains. Thus, we propose a coordinated stimulation model in which γ-γ communication is required to translate DNA sequence information from each γ to its respective motor domain.
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Affiliation(s)
- Marina Besprozvannaya
- From the Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138
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28
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Cattoni DI, Chara O, Godefroy C, Margeat E, Trigueros S, Milhiet PE, Nöllmann M. SpoIIIE mechanism of directional translocation involves target search coupled to sequence-dependent motor stimulation. EMBO Rep 2013; 14:473-9. [PMID: 23559069 DOI: 10.1038/embor.2013.39] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 11/09/2022] Open
Abstract
SpoIIIE/FtsK are membrane-anchored, ATP-fuelled, directional motors responsible for chromosomal segregation in bacteria. Directionality in these motors is governed by interactions between specialized sequence-recognition modules (SpoIIIE-γ/FtsK-γ) and highly skewed chromosomal sequences (SRS/KOPS). Using a new combination of ensemble and single-molecule methods, we dissect the series of steps required for SRS localization and motor activation. First, we demonstrate that SpoIIIE/DNA association kinetics are sequence independent, with binding specificity being uniquely determined by dissociation. Next, we show by single-molecule and modelling methods that hexameric SpoIIIE binds DNA non-specifically and finds SRS by an ATP-independent target search mechanism, with ensuing oligomerization and binding of SpoIIIE-γ to SRS triggering motor stimulation. Finally, we propose a new model that provides an entirely new interpretation of previous observations for the origin of SRS/KOPS-directed translocation by SpoIIIE/FtsK.
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Affiliation(s)
- Diego I Cattoni
- Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Université de Montpellier I & II, 34090 Montpellier, France
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29
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Galletto R, Tomko EJ. Translocation of Saccharomyces cerevisiae Pif1 helicase monomers on single-stranded DNA. Nucleic Acids Res 2013; 41:4613-27. [PMID: 23446274 PMCID: PMC3632115 DOI: 10.1093/nar/gkt117] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In Saccharomyces cerevisiae Pif1 participates in a wide variety of DNA metabolic pathways both in the nucleus and in mitochondria. The ability of Pif1 to hydrolyse ATP and catalyse unwinding of duplex nucleic acid is proposed to be at the core of its functions. We recently showed that upon binding to DNA Pif1 dimerizes and we proposed that a dimer of Pif1 might be the species poised to catalysed DNA unwinding. In this work we show that monomers of Pif1 are able to translocate on single-stranded DNA with 5′ to 3′ directionality. We provide evidence that the translocation activity of Pif1 could be used in activities other than unwinding, possibly to displace proteins from ssDNA. Moreover, we show that monomers of Pif1 retain some unwinding activity although a dimer is clearly a better helicase, suggesting that regulation of the oligomeric state of Pif1 could play a role in its functioning as a helicase or a translocase. Finally, although we show that Pif1 can translocate on ssDNA, the translocation profiles suggest the presence on ssDNA of two populations of Pif1, both able to translocate with 5′ to 3′ directionality.
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Affiliation(s)
- Roberto Galletto
- 252 McDonnell Science Building, Department of Biochemistry and Molecular Biophysics, Washington University, School of Medicine, 660 South Euclid Avenue, MS8231, Saint Louis, MO 63110,
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30
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Demarre G, Galli E, Barre FX. The FtsK Family of DNA Pumps. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 767:245-62. [PMID: 23161015 DOI: 10.1007/978-1-4614-5037-5_12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Interest for proteins of the FtsK family initially arose from their implication in many primordial processes in which DNA needs to be transported from one cell compartment to another in eubacteria. In the first section of this chapter, we address a list of the cellular functions of the different members of the FtsK family that have been so far studied. Soon after their discovery, interest for the FstK proteins spread because of their unique biochemical properties: most DNA transport systems rely on the assembly of complex multicomponent machines. In contrast, six FtsK proteins are sufficient to assemble into a fast and powerful DNA pump; the pump transports closed circular double stranded DNA molecules without any covalent-bond breakage nor topological alteration; transport is oriented despite the intrinsic symmetrical nature of the double stranded DNA helix and can occur across cell membranes. The different activities required for the oriented transport of DNA across cell compartments are achieved by three separate modules within the FtsK proteins: a DNA translocation module, an orientation module and an anchoring module. In the second part of this chapter, we review the structural and biochemical properties of these different modules.
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Affiliation(s)
- Gaëlle Demarre
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, Cedex, France,
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31
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Das B, Martínez E, Midonet C, Barre FX. Integrative mobile elements exploiting Xer recombination. Trends Microbiol 2012; 21:23-30. [PMID: 23127381 DOI: 10.1016/j.tim.2012.10.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 12/30/2022]
Abstract
Integrative mobile genetic elements directly participate in the rapid response of bacteria to environmental challenges. They generally encode their own dedicated recombination machineries. CTXφ, a filamentous bacteriophage that harbors the genes encoding cholera toxin in Vibrio cholerae provided the first notable exception to this rule: it hijacks XerC and XerD, two chromosome-encoded tyrosine recombinases for lysogenic conversion. XerC and XerD are highly conserved in bacteria because of their role in the topological maintenance of circular chromosomes and, with the advent of high throughput sequencing, numerous other integrative mobile elements exploiting them have been discovered. Here, we review our understanding of the molecular mechanisms of integration of the different integrative mobile elements exploiting Xer (IMEXs) so far described.
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Affiliation(s)
- Bhabatosh Das
- CNRS, Centre de Génétique Moléculaire, 91198 Gif-sur-Yvette, France
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32
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Abstract
Cells are capable of a variety of dramatic stimuli-responsive mechanical behaviors. These capabilities are enabled by the pervading cytoskeletal network, an active gel composed of structural filaments (e.g., actin) that are acted upon by motor proteins (e.g., myosin). Here, we describe the synthesis and characterization of an active gel using noncytoskeletal components. We use methods of base-pair-templated DNA self assembly to create a hybrid DNA gel containing stiff tubes and flexible linkers. We then activate the gel by adding the motor FtsK50C, a construct derived from the bacterial protein FtsK that, in vitro, has a strong and processive DNA contraction activity. The motors stiffen the gel and create stochastic contractile events that affect the positions of attached beads. We quantify the fluctuations of the beads and show that they are comparable both to measurements of cytoskeletal systems and to theoretical predictions for active gels. Thus, we present a DNA-based active gel whose behavior highlights the universal aspects of nonequilibrium, motor-driven networks.
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33
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Single-molecule imaging of DNA curtains reveals mechanisms of KOPS sequence targeting by the DNA translocase FtsK. Proc Natl Acad Sci U S A 2012; 109:6531-6. [PMID: 22493241 DOI: 10.1073/pnas.1201613109] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
FtsK is a hexameric DNA translocase that participates in the final stages of bacterial chromosome segregation. Here we investigate the DNA-binding and translocation activities of FtsK in real time by imaging fluorescently tagged proteins on nanofabricated curtains of DNA. We show that FtsK preferentially loads at 8-bp KOPS (FtsK Orienting Polar Sequences) sites and that loading is enhanced in the presence of ADP. We also demonstrate that FtsK locates KOPS through a mechanism that does not involve extensive 1D diffusion at the scale of our resolution. Upon addition of ATP, KOPS-bound FtsK translocates in the direction dictated by KOPS polarity, and once FtsK has begun translocating it does not rerecognize KOPS from either direction. However, FtsK can abruptly change directions while translocating along DNA independent of KOPS, suggesting that the ability to reorient on DNA does not arise from DNA sequence-specific effects. Taken together, our data support a model in which FtsK locates KOPS through random collisions, preferentially engages KOPS in the ADP-bound state, translocates in the direction dictated by the polar orientation of KOPS, and is incapable of recognizing KOPS while translocating along DNA.
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Nolivos S, Touzain F, Pages C, Coddeville M, Rousseau P, El Karoui M, Le Bourgeois P, Cornet F. Co-evolution of segregation guide DNA motifs and the FtsK translocase in bacteria: identification of the atypical Lactococcus lactis KOPS motif. Nucleic Acids Res 2012; 40:5535-45. [PMID: 22373923 PMCID: PMC3384302 DOI: 10.1093/nar/gks171] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Bacteria use the global bipolarization of their chromosomes into replichores to control the dynamics and segregation of their genome during the cell cycle. This involves the control of protein activities by recognition of specific short DNA motifs whose orientation along the chromosome is highly skewed. The KOPS motifs act in chromosome segregation by orienting the activity of the FtsK DNA translocase towards the terminal replichore junction. KOPS motifs have been identified in γ-Proteobacteria and in Bacillus subtilis as closely related G-rich octamers. We have identified the KOPS motif of Lactococcus lactis, a model bacteria of the Streptococcaceae family harbouring a compact and low GC% genome. This motif, 5′-GAAGAAG-3, was predicted in silico using the occurrence and skew characteristics of known KOPS motifs. We show that it is specifically recognized by L. lactis FtsK in vitro and controls its activity in vivo. L. lactis KOPS is thus an A-rich heptamer motif. Our results show that KOPS-controlled chromosome segregation is conserved in Streptococcaceae but that KOPS may show important variation in sequence and length between bacterial families. This suggests that FtsK adapts to its host genome by selecting motifs with convenient occurrence frequencies and orientation skews to orient its activity.
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Affiliation(s)
- Sophie Nolivos
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Université de Toulouse, Université Paul Sabatier, F-31000, Toulouse, France
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Allemand JF, Maier B, Smith DE. Molecular motors for DNA translocation in prokaryotes. Curr Opin Biotechnol 2012; 23:503-9. [PMID: 22226958 DOI: 10.1016/j.copbio.2011.12.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/08/2011] [Accepted: 12/19/2011] [Indexed: 11/25/2022]
Abstract
DNA transport is an essential life process. From chromosome separation during cell division or sporulation, to DNA virus ejection or encapsidation, to horizontal gene transfer, it is ubiquitous in all living organisms. Directed DNA translocation is often energetically unfavorable and requires an active process that uses energy, namely the action of molecular motors. In this review we present recent advances in the understanding of three molecular motors involved in DNA transport in prokaryotes, paying special attention to recent studies using single-molecule techniques. We first discuss DNA transport during cell division, then packaging of DNA in phage capsids, and then DNA import during bacterial transformation.
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Affiliation(s)
- Jean-François Allemand
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, UMR 8550 CNRS, Universités Pierre et Marie Curie and Paris Diderot, Département de Physique, 24 rue Lhomond, 75231 Paris Cedex 05, France.
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Kaimer C, Graumann PL. Players between the worlds: multifunctional DNA translocases. Curr Opin Microbiol 2011; 14:719-25. [PMID: 22047950 DOI: 10.1016/j.mib.2011.10.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/04/2011] [Accepted: 10/10/2011] [Indexed: 01/17/2023]
Abstract
DNA translocases play important roles during the bacterial cell cycle and in cell differentiation. Escherichia coli cells contain a multifunctional translocase, FtsK, which is involved in cell division, late steps of chromosome segregation and dimer resolution. In Gram-positive bacteria, the latter two processes are achieved by two translocases, SftA and SpoIIIE. These two translocases operate in a two step fashion, before and after closure of the division septum. DNA translocases have the remarkable ability to translocate DNA in a vectorial manner, orienting themselves according to polar sequences present in bacterial genomes, and perform various additional roles during the cell cycle. DNA translocases genetically interact with Structural Maintenance of Chromosomes (SMC) proteins in a flexible manner in different species, underlining the high versatility of this class of proteins.
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Affiliation(s)
- Christine Kaimer
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA 94720, USA
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Domazet-Lošo M, Haubold B. Alignment-free detection of horizontal gene transfer between closely related bacterial genomes. Mob Genet Elements 2011; 1:230-235. [PMID: 22312592 DOI: 10.4161/mge.1.3.18065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 09/13/2011] [Indexed: 11/19/2022] Open
Abstract
Bacterial epidemics are often caused by strains that have acquired their increased virulence through horizontal gene transfer. Due to this association with disease, the detection of horizontal gene transfer continues to receive attention from microbiologists and bioinformaticians alike. Most software for detecting transfer events is based on alignments of sets of genes or of entire genomes. But despite great advances in the design of algorithms and computer programs, genome alignment remains computationally challenging. We have therefore developed an alignment-free algorithm for rapidly detecting horizontal gene transfer between closely related bacterial genomes. Our implementation of this algorithm is called alfy for "ALignment Free local homologY" and is freely available from http://guanine.evolbio.mpg.de/alfy/. In this comment we demonstrate the application of alfy to the genomes of Staphylococcus aureus. We also argue that-contrary to popular belief and in spite of increasing computer speed-algorithmic optimization is becoming more, not less, important if genome data continues to accumulate at the present rate.
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Affiliation(s)
- Mirjana Domazet-Lošo
- Faculty of Electrical Engineering and Computing; Department of Applied Computing; University of Zagreb; Zagreb, Croatia
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Sepulveda E, Vogelmann J, Muth G. A septal chromosome segregator protein evolved into a conjugative DNA-translocator protein. Mob Genet Elements 2011; 1:225-229. [PMID: 22479692 DOI: 10.4161/mge.1.3.18066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/12/2011] [Accepted: 09/13/2011] [Indexed: 02/01/2023] Open
Abstract
Streptomycetes, Gram-positive soil bacteria well known for the production of antibiotics feature a unique conjugative DNA transfer system. In contrast to classical conjugation which is characterized by the secretion of a pilot protein covalently linked to a single-stranded DNA molecule, in Streptomyces a double-stranded DNA molecule is translocated during conjugative transfer. This transfer involves a single plasmid encoded protein, TraB. A detailed biochemical and biophysical characterization of TraB, revealed a close relationship to FtsK, mediating chromosome segregation during bacterial cell division. TraB translocates plasmid DNA by recognizing 8-bp direct repeats located in a specific plasmid region clt. Similar sequences accidentally also occur on chromosomes and have been shown to be bound by TraB. We suggest that TraB mobilizes chromosomal genes by the interaction with these chromosomal clt-like sequences not relying on the integration of the conjugative plasmid into the chromosome.
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Affiliation(s)
- Edgardo Sepulveda
- Interfakultaeres Institut für Mikrobiologie und Infektionsmedizin Tuebingen IMIT; Mikrobiologie/Biotechnologie; Eberhard Karls Universitaet Tuebingen; Tuebingen, Germany
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Deghorain M, Pagès C, Meile JC, Stouf M, Capiaux H, Mercier R, Lesterlin C, Hallet B, Cornet F. A defined terminal region of the E. coli chromosome shows late segregation and high FtsK activity. PLoS One 2011; 6:e22164. [PMID: 21799784 PMCID: PMC3140498 DOI: 10.1371/journal.pone.0022164] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 06/16/2011] [Indexed: 11/19/2022] Open
Abstract
Background The FtsK DNA-translocase controls the last steps of chromosome segregation in E. coli. It translocates sister chromosomes using the KOPS DNA motifs to orient its activity, and controls the resolution of dimeric forms of sister chromosomes by XerCD-mediated recombination at the dif site and their decatenation by TopoIV. Methodology We have used XerCD/dif recombination as a genetic trap to probe the interaction of FtsK with loci located in different regions of the chromosome. This assay revealed that the activity of FtsK is restricted to a ∼400 kb terminal region of the chromosome around the natural position of the dif site. Preferential interaction with this region required the tethering of FtsK to the division septum via its N-terminal domain as well as its translocation activity. However, the KOPS-recognition activity of FtsK was not required. Displacement of replication termination outside the FtsK high activity region had no effect on FtsK activity and deletion of a part of this region was not compensated by its extension to neighbouring regions. By observing the fate of fluorescent-tagged loci of the ter region, we found that segregation of the FtsK high activity region is delayed compared to that of its adjacent regions. Significance Our results show that a restricted terminal region of the chromosome is specifically dedicated to the last steps of chromosome segregation and to their coupling with cell division by FtsK.
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Affiliation(s)
- Marie Deghorain
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
- Université Catholique de Louvain, Institut des Sciences de la Vie, Unité de Génétique, Louvain-La-Neuve, Belgium
| | - Carine Pagès
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Jean-Christophe Meile
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Mathieu Stouf
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Hervé Capiaux
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Romain Mercier
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Christian Lesterlin
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Bernard Hallet
- Université Catholique de Louvain, Institut des Sciences de la Vie, Unité de Génétique, Louvain-La-Neuve, Belgium
| | - François Cornet
- Laboratoire de Microbiologie et de Génétique Moléculaire, CNRS, Toulouse, France
- Université de Toulouse, Université Paul Sabatier, Toulouse, France
- * E-mail:
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Grainge I, Lesterlin C, Sherratt DJ. Activation of XerCD-dif recombination by the FtsK DNA translocase. Nucleic Acids Res 2011; 39:5140-8. [PMID: 21371996 PMCID: PMC3130261 DOI: 10.1093/nar/gkr078] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The FtsK translocase pumps dsDNA directionally at ∼5 kb/s and facilitates chromosome unlinking by activating XerCD site-specific recombination at dif, located in the replication terminus of the Escherichia coli chromosome. We show directly that the γ regulatory subdomain of FtsK activates XerD catalytic activity to generate Holliday junction intermediates that can then be resolved by XerC. Furthermore, we demonstrate that γ can activate XerCD-dif recombination in the absence of the translocase domain, when it is fused to XerCD, or added in isolation. In these cases the recombination products are topologically complex and would impair chromosome unlinking. We propose that FtsK translocation and activation of unlinking are normally coupled, with the translocation being essential for ensuring that the products of recombination are topologically unlinked, an essential feature of the role of FtsK in chromosome segregation.
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Affiliation(s)
- Ian Grainge
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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