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Schramm T, Lubrano P, Pahl V, Stadelmann A, Verhülsdonk A, Link H. Mapping temperature-sensitive mutations at a genome scale to engineer growth switches in Escherichia coli. Mol Syst Biol 2023; 19:e11596. [PMID: 37642940 PMCID: PMC10568205 DOI: 10.15252/msb.202311596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 08/14/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023] Open
Abstract
Temperature-sensitive (TS) mutants are a unique tool to perturb and engineer cellular systems. Here, we constructed a CRISPR library with 15,120 Escherichia coli mutants, each with a single amino acid change in one of 346 essential proteins. 1,269 of these mutants showed temperature-sensitive growth in a time-resolved competition assay. We reconstructed 94 TS mutants and measured their metabolism under growth arrest at 42°C using metabolomics. Metabolome changes were strong and mutant-specific, showing that metabolism of nongrowing E. coli is perturbation-dependent. For example, 24 TS mutants of metabolic enzymes overproduced the direct substrate metabolite due to a bottleneck in their associated pathway. A strain with TS homoserine kinase (ThrBF267D ) produced homoserine for 24 h, and production was tunable by temperature. Finally, we used a TS subunit of DNA polymerase III (DnaXL289Q ) to decouple growth from arginine overproduction in engineered E. coli. These results provide a strategy to identify TS mutants en masse and demonstrate their large potential to produce bacterial metabolites with nongrowing cells.
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Affiliation(s)
- Thorben Schramm
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
- Present address:
Department of Biology, Institute of Molecular Systems BiologyETH ZurichZürichSwitzerland
| | - Paul Lubrano
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
| | - Vanessa Pahl
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
| | - Amelie Stadelmann
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
| | - Andreas Verhülsdonk
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
| | - Hannes Link
- Interfaculty Institute of Microbiology and Infection MedicineUniversity of TübingenTübingenGermany
- Cluster of Excellence “Controlling Microbes to Fight Infections”University of TübingenTübingenGermany
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2
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Marsin S, Adam Y, Cargemel C, Andreani J, Baconnais S, Legrand P, Li de la Sierra-Gallay I, Humbert A, Aumont-Nicaise M, Velours C, Ochsenbein F, Durand D, Le Cam E, Walbott H, Possoz C, Quevillon-Cheruel S, Ferat JL. Study of the DnaB:DciA interplay reveals insights into the primary mode of loading of the bacterial replicative helicase. Nucleic Acids Res 2021; 49:6569-6586. [PMID: 34107018 PMCID: PMC8216460 DOI: 10.1093/nar/gkab463] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 05/07/2021] [Accepted: 05/17/2021] [Indexed: 01/04/2023] Open
Abstract
Replicative helicases are essential proteins that unwind DNA in front of replication forks. Their loading depends on accessory proteins and in bacteria, DnaC and DnaI are well characterized loaders. However, most bacteria do not express either of these two proteins. Instead, they are proposed to rely on DciA, an ancestral protein unrelated to DnaC/I. While the DciA structure from Vibrio cholerae shares no homology with DnaC, it reveals similarities with DnaA and DnaX, two proteins involved during replication initiation. As other bacterial replicative helicases, VcDnaB adopts a toroid-shaped homo-hexameric structure, but with a slightly open dynamic conformation in the free state. We show that VcDnaB can load itself on DNA in vitro and that VcDciA stimulates this function, resulting in an increased DNA unwinding. VcDciA interacts with VcDnaB with a 3/6 stoichiometry and we show that a determinant residue, which discriminates DciA- and DnaC/I-helicases, is critical in vivo. Our work is the first step toward the understanding of the ancestral mode of loading of bacterial replicative helicases on DNA. It sheds light on the strategy employed by phage helicase loaders to hijack bacterial replicative helicases and may explain the recurrent domestication of dnaC/I through evolution in bacteria.
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Affiliation(s)
| | | | | | - Jessica Andreani
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Sonia Baconnais
- Genome Integrity and Cancer UMR 9019 CNRS, Université Paris Saclay, Gustave Roussy 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Pierre Legrand
- Synchrotron SOLEIL, L’Orme des Merisiers, 91192 Gif-sur-Yvette, France
| | - Ines Li de la Sierra-Gallay
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Adeline Humbert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Magali Aumont-Nicaise
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Christophe Velours
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Françoise Ochsenbein
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Dominique Durand
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Eric Le Cam
- Genome Integrity and Cancer UMR 9019 CNRS, Université Paris Saclay, Gustave Roussy 114 rue Edouard Vaillant, 94805 Villejuif, France
| | - Hélène Walbott
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Christophe Possoz
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
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3
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Papiran R, Hamedi J. Adaptive Evolution of Lactococcus Lactis to Thermal and Oxidative Stress Increases Biomass and Nisin Production. Appl Biochem Biotechnol 2021; 193:3425-3441. [PMID: 34196920 DOI: 10.1007/s12010-021-03609-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/21/2021] [Indexed: 02/07/2023]
Abstract
High values of agitation and temperature lead to stressful conditions in the fermentations of Lactococcus lactis due to its aero-tolerant and mesophilic nature. Here, the adaptive laboratory evolution (ALE) technique was applied to increase biomass and nisin production yields by enhancing L. lactis subsp. lactis robustness at higher growth temperature and aeration rates. In two separate ALE experiments, after 162 serial transfers, optimum agitation and growth temperature of L. lactis were shifted from 40 rpm and 30 °C to 200 rpm and 37 °C, respectively. Oxidative and acid resistance were enhanced in the evolved strain. Whole-genome sequencing revealed the emergence of five single-nucleotide polymorphisms in the genome of the evolved strain in jag, DnaB, ArgR, cation transporter genes, and one putative protein. The evolved strain of L. lactis in this study has more industrial desirable features and improved nisin production capability and can act more efficiently in nisin production in stressful conditions.
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Affiliation(s)
- Reyhaneh Papiran
- Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran
- Microbial Technology and Products (MTP) Research Center, University of Tehran, Tehran, Iran
| | - Javad Hamedi
- Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran.
- Microbial Technology and Products (MTP) Research Center, University of Tehran, Tehran, Iran.
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4
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Hayashi C, Miyazaki E, Ozaki S, Abe Y, Katayama T. DnaB helicase is recruited to the replication initiation complex via binding of DnaA domain I to the lateral surface of the DnaB N-terminal domain. J Biol Chem 2020; 295:11131-11143. [PMID: 32540966 DOI: 10.1074/jbc.ra120.014235] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/10/2020] [Indexed: 01/09/2023] Open
Abstract
The DNA replication protein DnaA in Escherichia coli constructs higher-order complexes on the origin, oriC, to unwind this region. DnaB helicase is loaded onto unwound oriC via interactions with the DnaC loader and the DnaA complex. The DnaB-DnaC complex is recruited to the DnaA complex via stable binding of DnaB to DnaA domain I. The DnaB-DnaC complex is then directed to unwound oriC via a weak interaction between DnaB and DnaA domain III. Previously, we showed that Phe46 in DnaA domain I binds to DnaB. Here, we searched for the DnaA domain I-binding site in DnaB. The DnaB L160A variant was impaired in binding to DnaA complex on oriC but retained its DnaC-binding and helicase activities. DnaC binding moderately stimulated DnaA binding of DnaB L160A, and loading of DnaB L160A onto oriC was consistently and moderately inhibited. In a helicase assay with partly single-stranded DNA bearing a DnaA-binding site, DnaA stimulated DnaB loading, which was strongly inhibited in DnaB L160A even in the presence of DnaC. DnaB L160A was functionally impaired in vivo On the basis of these findings, we propose that DnaB Leu160 interacts with DnaA domain I Phe46 DnaB Leu160 is exposed on the lateral surface of the N-terminal domain, which can explain unobstructed interactions of DnaA domain I-bound DnaB with DnaC, DnaG primase, and DnaA domain III. We propose a probable structure for the DnaA-DnaB-DnaC complex, which could be relevant to the process of DnaB loading onto oriC.
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Affiliation(s)
- Chihiro Hayashi
- Department of Molecular Biology, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan
| | - Erika Miyazaki
- Department of Molecular Biology, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan
| | - Shogo Ozaki
- Department of Molecular Biology, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan
| | - Yoshito Abe
- Department of Protein Structure, Function, and Design, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan.,Department of Pharmaceutical Sciences, International University of Health and Welfare, Okawa, Japan
| | - Tsutomu Katayama
- Department of Molecular Biology, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan
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5
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Schramm T, Lempp M, Beuter D, Sierra SG, Glatter T, Link H. High-throughput enrichment of temperature-sensitive argininosuccinate synthetase for two-stage citrulline production in E. coli. Metab Eng 2020; 60:14-24. [PMID: 32179161 PMCID: PMC7225747 DOI: 10.1016/j.ymben.2020.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/03/2020] [Accepted: 03/08/2020] [Indexed: 12/20/2022]
Abstract
Controlling metabolism of engineered microbes is important to modulate cell growth and production during a bioprocess. For example, external parameters such as light, chemical inducers, or temperature can act on metabolism of production strains by changing the abundance or activity of enzymes. Here, we created temperature-sensitive variants of an essential enzyme in arginine biosynthesis of Escherichia coli (argininosuccinate synthetase, ArgG) and used them to dynamically control citrulline overproduction and growth of E. coli. We show a method for high-throughput enrichment of temperature-sensitive ArgG variants with a fluorescent TIMER protein and flow cytometry. With 90 of the thus derived ArgG variants, we complemented an ArgG deletion strain showing that 90% of the strains exhibit temperature-sensitive growth and 69% of the strains are auxotrophic for arginine at 42 °C and prototrophic at 30 °C. The best temperature-sensitive ArgG variant enabled precise and tunable control of cell growth by temperature changes. Expressing this variant in a feedback-dysregulated E. coli strain allowed us to realize a two-stage bioprocess: a 33 °C growth-phase for biomass accumulation and a 39 °C stationary-phase for citrulline production. With this two-stage strategy, we produced 3 g/L citrulline during 45 h cultivation in a 1-L bioreactor. These results show that temperature-sensitive enzymes can be created en masse and that they may function as metabolic valves in engineered bacteria. Method to enrich temperature-sensitive enzymes en masse. Temperature-sensitive enzymes function as metabolic valve. Temperature controlled two-stage production of citrulline.
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Affiliation(s)
- Thorben Schramm
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Martin Lempp
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Dominik Beuter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Silvia González Sierra
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany
| | - Hannes Link
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 16, 35043, Marburg, Germany.
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6
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Henrikus SS, Henry C, Ghodke H, Wood EA, Mbele N, Saxena R, Basu U, van Oijen AM, Cox MM, Robinson A. RecFOR epistasis group: RecF and RecO have distinct localizations and functions in Escherichia coli. Nucleic Acids Res 2019; 47:2946-2965. [PMID: 30657965 PMCID: PMC6451095 DOI: 10.1093/nar/gkz003] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 12/03/2018] [Accepted: 01/10/2019] [Indexed: 01/31/2023] Open
Abstract
In bacteria, genetic recombination is a major mechanism for DNA repair. The RecF, RecO and RecR proteins are proposed to initiate recombination by loading the RecA recombinase onto DNA. However, the biophysical mechanisms underlying this process remain poorly understood. Here, we used genetics and single-molecule fluorescence microscopy to investigate whether RecF and RecO function together, or separately, in live Escherichia coli cells. We identified conditions in which RecF and RecO functions are genetically separable. Single-molecule imaging revealed key differences in the spatiotemporal behaviours of RecF and RecO. RecF foci frequently colocalize with replisome markers. In response to DNA damage, colocalization increases and RecF dimerizes. The majority of RecF foci are dependent on RecR. Conversely, RecO foci occur infrequently, rarely colocalize with replisomes or RecF and are largely independent of RecR. In response to DNA damage, RecO foci appeared to spatially redistribute, occupying a region close to the cell membrane. These observations indicate that RecF and RecO have distinct functions in the DNA damage response. The observed localization of RecF to the replisome supports the notion that RecF helps to maintain active DNA replication in cells carrying DNA damage.
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Affiliation(s)
- Sarah S Henrikus
- Molecular Horizons Institute and School of Chemistry and Biomolecular Science, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2500, Australia
| | - Camille Henry
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Harshad Ghodke
- Molecular Horizons Institute and School of Chemistry and Biomolecular Science, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2500, Australia
| | - Elizabeth A Wood
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Neema Mbele
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Roopashi Saxena
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Upasana Basu
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Antoine M van Oijen
- Molecular Horizons Institute and School of Chemistry and Biomolecular Science, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2500, Australia
| | - Michael M Cox
- Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
| | - Andrew Robinson
- Molecular Horizons Institute and School of Chemistry and Biomolecular Science, University of Wollongong, Wollongong, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW 2500, Australia
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7
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Processing closely spaced lesions during Nucleotide Excision Repair triggers mutagenesis in E. coli. PLoS Genet 2017; 13:e1006881. [PMID: 28686598 PMCID: PMC5521853 DOI: 10.1371/journal.pgen.1006881] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/21/2017] [Accepted: 06/21/2017] [Indexed: 11/19/2022] Open
Abstract
It is generally assumed that most point mutations are fixed when damage containing template DNA undergoes replication, either right at the fork or behind the fork during gap filling. Here we provide genetic evidence for a pathway, dependent on Nucleotide Excision Repair, that induces mutations when processing closely spaced lesions. This pathway, referred to as Nucleotide Excision Repair-induced Mutagenesis (NERiM), exhibits several characteristics distinct from mutations that occur within the course of replication: i) following UV irradiation, NER-induced mutations are fixed much more rapidly (t ½ ≈ 30 min) than replication dependent mutations (t ½ ≈ 80–100 min) ii) NERiM specifically requires DNA Pol IV in addition to Pol V iii) NERiM exhibits a two-hit dose-response curve that suggests processing of closely spaced lesions. A mathematical model let us define the geometry (infer the structure) of the toxic intermediate as being formed when NER incises a lesion that resides in close proximity of another lesion in the complementary strand. This critical NER intermediate requires Pol IV / Pol II for repair, it is either lethal if left unrepaired or mutation-prone when repaired. Finally, NERiM is found to operate in stationary phase cells providing an intriguing possibility for ongoing evolution in the absence of replication. In this paper, we report the surprising finding that in addition to the well-known properties of Nucleotide Excision Repair (NER) in efficiently repairing a large number of DNA lesions, NER entails a mutagenic sub-pathway. Our data suggest that closely spaced lesions are processed by NER into a toxic DNA intermediate, i.e. a gap containing a lesion, that leads either to mutagenesis during its repair or to cell death in the absence of repair. The paper describes a new pathway for the generation of mutations in stationary phase bacteria or quiescent cells; it also provides an additional role for Pol IV, the most widely distributed specialized DNA polymerase in all forms of life.
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8
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Mettrick KA, Grainge I. Stability of blocked replication forks in vivo. Nucleic Acids Res 2016; 44:657-68. [PMID: 26490956 PMCID: PMC4737137 DOI: 10.1093/nar/gkv1079] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 10/06/2015] [Accepted: 10/07/2015] [Indexed: 11/17/2022] Open
Abstract
Replication of chromosomal DNA must be carried out to completion in order for a cell to proliferate. However, replication forks can stall during this process for a variety of reasons, including nucleoprotein 'roadblocks' and DNA lesions. In these circumstances the replisome copying the DNA may disengage from the chromosome to allow various repair processes to restore DNA integrity and enable replication to continue. Here, we report the in vivo stability of the replication fork when it encounters a nucleoprotein blockage in Escherichia coli. Using a site-specific and reversible protein block system in conjunction with the temperature sensitive DnaC helicase loader and DnaB replicative helicase, we monitored the disappearance of the Y-shaped DNA replication fork structures using neutral-neutral 2D agarose gels. We show the replication fork collapses within 5 min of encountering the roadblock. Therefore, the stalled replication fork does not pause at a block in a stable confirmation for an extended period of time as previously postulated.
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Affiliation(s)
- Karla A Mettrick
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Ian Grainge
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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9
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Fate of the replisome following arrest by UV-induced DNA damage in Escherichia coli. Proc Natl Acad Sci U S A 2013; 110:11421-6. [PMID: 23801750 DOI: 10.1073/pnas.1300624110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Accurate replication in the presence of DNA damage is essential to genome stability and viability in all cells. In Escherichia coli, DNA replication forks blocked by UV-induced damage undergo a partial resection and RecF-catalyzed regression before synthesis resumes. These processing events generate distinct structural intermediates on the DNA that can be visualized in vivo using 2D agarose gels. However, the fate and behavior of the stalled replisome remains a central uncharacterized question. Here, we use thermosensitive mutants to show that the replisome's polymerases uncouple and transiently dissociate from the DNA in vivo. Inactivation of α, β, or τ subunits within the replisome is sufficient to signal and induce the RecF-mediated processing events observed following UV damage. By contrast, the helicase-primase complex (DnaB and DnaG) remains critically associated with the fork, leading to a loss of fork integrity, degradation, and aberrant intermediates when disrupted. The results reveal a dynamic replisome, capable of partial disassembly to allow access to the obstruction, while retaining subunits that maintain fork licensing and direct reassembly to the appropriate location after processing has occurred.
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10
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Ikeda M, Shinozaki Y, Uchida K, Ohshika Y, Furukohri A, Maki H, Akiyama MT. Quick replication fork stop by overproduction of Escherichia coli DinB produces non-proliferative cells with an aberrant chromosome. Genes Genet Syst 2013; 87:221-31. [PMID: 23229309 DOI: 10.1266/ggs.87.221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Escherichia coli dinB encodes the translesion DNA polymerase DinB, which can inhibit progression of replication forks in a dose-dependent manner, independent of exogenous DNA damage. We reported previously that overproduction of DinB from a multicopy dinB plasmid immediately abolished ongoing replication fork progression, and the cells rapidly and drastically lost colony-forming ability, although the mechanisms underlying this lethality by severe replication fork stress remained unclear. Here, we show that the reduced colony-forming ability in the dinB-overexpressing cells is independent of the specific toxin genes that trigger programmed bacterial cell death when replication is blocked by depletion of the dNTP pool. After DinB abolished replication fork progression and colony-forming ability, most of the cells were still viable, as judged by fluorescent dye staining, but contained irregularly shaped nucleoids in which chromosomal DNA was preferentially lost in the replication terminus region relative to the replication origin region. Flow cytometric analysis of the cells revealed chromosomal damage and the eventual appearance of cell populations with less than single-chromosome DNA content, reminiscent of sub-G1 cells with lethal DNA content produced during eukaryotic apoptosis. This reduced DNA content was not observed after replication fork progression was quickly stopped in temperature-sensitive dnaB helicase mutant cells at a non-permissive temperature. Thus, the quick replication stop provoked by excess DinB uniquely generates temporarily viable but non-reproductive cells possessing a fatally depleted chromosomal content, which may represent one of the possible fates of an E. coli cell whose replication is overwhelmingly compromised.
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Affiliation(s)
- Mio Ikeda
- Division of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama,Ikoma, Nara 630-0192, Japan
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11
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Lia G, Rigato A, Long E, Chagneau C, Le Masson M, Allemand JF, Michel B. RecA-promoted, RecFOR-independent progressive disassembly of replisomes stalled by helicase inactivation. Mol Cell 2012; 49:547-57. [PMID: 23260658 DOI: 10.1016/j.molcel.2012.11.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/17/2012] [Accepted: 11/16/2012] [Indexed: 11/26/2022]
Abstract
In all organisms, replication impairment is a recognized source of genomic instability, raising an increasing interest in the fate of inactivated replication forks. We used Escherichia coli strains with a temperature-inactivated replicative helicase (DnaB) and in vivo single-molecule microscopy to quantify the detailed molecular processing of stalled replication forks. After helicase inactivation, RecA binds to blocked replication forks and is essential for the rapid release of hPol III. The entire holoenzyme is disrupted little by little, with some components lost in few minutes, while others are stable in 70% of cells for at least 1 hr. Although replisome dissociation is delayed in a recA mutant, it is not affected by RecF or RecO inactivation. RecFOR are required for full RecA filaments formation, and we propose that polymerase clearance can be catalyzed by short, RecFOR-independent RecA filaments. Our results identify a function for the universally conserved, central recombination protein RecA.
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Affiliation(s)
- Giuseppe Lia
- CNRS, Centre de Génétique Moléculaire, UPR3404, Gif-sur-Yvette 91198, France.
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12
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Lia G, Michel B, Allemand JF. RETRACTED: Polymerase exchange during Okazaki fragment synthesis observed in living cells. Science 2012; 335:328-31. [PMID: 22194411 DOI: 10.1126/science.1210400] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
DNA replication machineries have been studied extensively, but the kinetics of action of their components remains largely unknown. We report a study of DNA synthesis during replication in living Escherichia coli cells. Using single-molecule microscopy, we observed repetitive fluorescence bursts of single polymerase IIIs (Pol IIIs), indicating polymerase exchange at the replication fork. Fluctuations in the amount of DNA-bound single-stranded DNA-binding protein (SSB) reflect different speeds for the leading- and lagging-strand DNA polymerases. Coincidence analyses of Pol III and SSB fluctuations show that they correspond to the lagging-strand synthesis and suggest the use of a new Pol III for each Okazaki fragment. Based on exchanges involving two Pol IIIs, we propose that the third polymerase in the replisome is involved in lagging-strand synthesis.
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Affiliation(s)
- Giuseppe Lia
- CNRS, Centre de Génétique Moléculaire, UPR3404, Gif-sur-Yvette F-91198, France.
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13
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Lee SJ, Richardson CC. Molecular basis for recognition of nucleoside triphosphate by gene 4 helicase of bacteriophage T7. J Biol Chem 2010; 285:31462-71. [PMID: 20688917 DOI: 10.1074/jbc.m110.156067] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The translocation of DNA helicases on single-stranded DNA and the unwinding of double-stranded DNA are fueled by the hydrolysis of nucleoside triphosphates (NTP). Although most helicases use ATP in these processes, the DNA helicase encoded by gene 4 of bacteriophage T7 uses dTTP most efficiently. To identify the structural requirements of the NTP, we determined the efficiency of DNA unwinding by T7 helicase using a variety of NTPs and their analogs. The 5-methyl group of thymine was critical for the efficient unwinding of DNA, although the presence of a 3'-ribosyl hydroxyl group partially overcame this requirement. The NTP-binding pocket of the protein was examined by randomly substituting amino acids for several amino acid residues (Thr-320, Arg-504, Tyr-535, and Leu-542) that the crystal structure suggests interact with the nucleotide. Although positions 320 and 542 required aliphatic residues of the appropriate size, an aromatic side chain was necessary at position 535 to stabilize NTP for efficient unwinding. A basic side chain of residue 504 was essential to interact with the 4-carbonyl of the thymine base of dTTP. Replacement of this residue with a small aliphatic residue allowed the accommodation of other NTPs, resulting in the preferential use of dATP and the use of dCTP, a nucleotide not normally used. Results from this study suggest that the NTP must be stabilized by specific interactions within the NTP-binding site of the protein to achieve efficient hydrolysis. These interactions dictate NTP specificity.
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Affiliation(s)
- Seung-Joo Lee
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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14
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Structural synergy and molecular crosstalk between bacterial helicase loaders and replication initiators. Cell 2008; 135:623-34. [PMID: 19013274 DOI: 10.1016/j.cell.2008.09.058] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Revised: 07/18/2008] [Accepted: 09/26/2008] [Indexed: 11/23/2022]
Abstract
The loading of oligomeric helicases onto replication origins marks an essential step in replisome assembly. In cells, dedicated AAA+ ATPases regulate loading, however, the mechanism by which these factors recruit and deposit helicases has remained unclear. To better understand this process, we determined the structure of the ATPase region of the bacterial helicase loader DnaC from Aquifex aeolicus to 2.7 A resolution. The structure shows that DnaC is a close paralog of the bacterial replication initiator, DnaA, and unexpectedly shares an ability to form a helical assembly similar to that of ATP-bound DnaA. Complementation and ssDNA-binding assays validate the importance of homomeric DnaC interactions, while pull-down experiments show that the DnaC and DnaA AAA+ domains interact in a nucleotide-dependent manner. These findings implicate DnaC as a molecular adaptor that uses ATP-activated DnaA as a docking site for regulating the recruitment and correct spatial deposition of the DnaB helicase onto origins.
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15
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Rosario CJ, Singer M. The Myxococcus xanthus developmental program can be delayed by inhibition of DNA replication. J Bacteriol 2007; 189:8793-800. [PMID: 17905977 PMCID: PMC2168630 DOI: 10.1128/jb.01361-07] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Under conditions of nutrient deprivation, Myxococcus xanthus undergoes a developmental process that results in the formation of a fruiting body containing environmentally resistant myxospores. We have shown that myxospores contain two copies of the genome, suggesting that cells must replicate the genome prior to or during development. To further investigate the role of DNA replication in development, a temperature-sensitive dnaB mutant, DnaB(A116V), was isolated from M. xanthus. Unlike what happens in Escherichia coli dnaB mutants, where DNA replication immediately halts upon a shift to a nonpermissive temperature, growth and DNA replication of the M. xanthus mutant ceased after one cell doubling at a nonpermissive temperature, 37 degrees C. We demonstrated that at the nonpermissive temperature the DnaB(A116V) mutant arrested as a population of 1n cells, implying that these cells could complete one round of the cell cycle but did not initiate new rounds of DNA replication. In developmental assays, the DnaB(A116V) mutant was unable to develop into fruiting bodies and produced fewer myxospores than the wild type at the nonpermissive temperature. However, the mutant was able to undergo development when it was shifted to a permissive temperature, suggesting that cells had the capacity to undergo DNA replication during development and to allow the formation of myxospores.
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16
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Griep MA, Blood S, Larson MA, Koepsell SA, Hinrichs SH. Myricetin inhibits Escherichia coli DnaB helicase but not primase. Bioorg Med Chem 2007; 15:7203-8. [PMID: 17851081 DOI: 10.1016/j.bmc.2007.07.057] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 06/29/2007] [Accepted: 07/03/2007] [Indexed: 10/22/2022]
Abstract
Primase and DnaB helicase play central roles during DNA replication initiation and elongation. Both enzymes are drug targets because they are essential, persistent among bacterial genomes, and have different sequences than their eukaryotic equivalents. Myricetin is a ubiquitous natural product in plants that is known to inhibit a variety of DNA polymerases, RNA polymerases, reverse transcriptases, and telomerases in addition being able to inhibit kinases and helicases. We have shown that myricetin inhibits Escherichia coli DnaB helicase according to a mechanism dominated by noncompetitive behavior with a K(i) of 10.0+/-0.5 microM. At physiological ATP concentration, myricetin inhibits E. coli DnaB helicase with an inhibitory concentration at 50% maximal (IC(50)) of 11.3+/-1.6 microM. In contrast, myricetin inhibited E. coli primase at least 60-fold weaker than DnaB helicase and far weaker than any other polymerase.
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Affiliation(s)
- Mark A Griep
- Department of Chemistry, University of Nebraska-Lincoln, 614 Hamilton Hall, Lincoln, NE 68588-0304, USA.
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17
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Belle JJ, Casey A, Courcelle CT, Courcelle J. Inactivation of the DnaB helicase leads to the collapse and degradation of the replication fork: a comparison to UV-induced arrest. J Bacteriol 2007; 189:5452-62. [PMID: 17526695 PMCID: PMC1951839 DOI: 10.1128/jb.00408-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 05/17/2007] [Indexed: 11/20/2022] Open
Abstract
Replication forks face a variety of structurally diverse impediments that can prevent them from completing their task. The mechanism by which cells overcome these hurdles is likely to vary depending on the nature of the obstacle and the strand in which the impediment is encountered. Both UV-induced DNA damage and thermosensitive replication proteins have been used in model systems to inhibit DNA replication and characterize the mechanism by which it recovers. In this study, we examined the molecular events that occur at replication forks following inactivation of a thermosensitive DnaB helicase and found that they are distinct from those that occur following arrest at UV-induced DNA damage. Following UV-induced DNA damage, the integrity of replication forks is maintained and protected from extensive degradation by RecA, RecF, RecO, and RecR until replication can resume. By contrast, inactivation of DnaB results in extensive degradation of the nascent and leading-strand template DNA and a loss of replication fork integrity as monitored by two-dimensional agarose gel analysis. The degradation that occurs following DnaB inactivation partially depends on several genes, including recF, recO, recR, recJ, recG, and xonA. Furthermore, the thermosensitive DnaB allele prevents UV-induced DNA degradation from occurring following arrest even at the permissive temperature, suggesting a role for DnaB prior to loading of the RecFOR proteins. We discuss these observations in relation to potential models for both UV-induced and DnaB(Ts)-mediated replication inhibition.
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Affiliation(s)
- Jerilyn J Belle
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi 39762, USA
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18
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Soni R, Mehra P, Mukhopadhyay G, Kumar Dhar S. Helicobacter pylori DnaB helicase can bypass Escherichia coli DnaC function in vivo. Biochem J 2005; 389:541-8. [PMID: 15836434 PMCID: PMC1175132 DOI: 10.1042/bj20050062] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In Escherichia coli, DnaC is essential for loading DnaB helicase at oriC (the origin of chromosomal DNA replication). The question arises as to whether this model can be generalized to other species, since many eubacterial species fail to possess dnaC in their genomes. Previously, we have reported the characterization of HpDnaB (Helicobacter pylori DnaB) both in vitro and in vivo. Interestingly, H. pylori does not have a DnaC homologue. Using two different E. coli dnaC (EcdnaC) temperature-sensitive mutant strains, we report here the complementation of EcDnaC function by HpDnaB in vivo. These observations strongly suggest that HpDnaB can bypass EcDnaC activity in vivo.
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Affiliation(s)
- Rajesh K. Soni
- Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India
| | - Parul Mehra
- Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India
| | - Gauranga Mukhopadhyay
- Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India
| | - Suman Kumar Dhar
- Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi-110067, India
- To whom correspondence should be addressed (email )
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19
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Huet G, Daffé M, Saves I. Identification of the Mycobacterium tuberculosis SUF machinery as the exclusive mycobacterial system of [Fe-S] cluster assembly: evidence for its implication in the pathogen's survival. J Bacteriol 2005; 187:6137-46. [PMID: 16109955 PMCID: PMC1196142 DOI: 10.1128/jb.187.17.6137-6146.2005] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The worldwide recrudescence of tuberculosis and widespread antibiotic resistance have strengthened the need for the rapid development of new antituberculous drugs targeting essential functions of its etiologic agent, Mycobacterium tuberculosis. In our search for new targets, we found that the M. tuberculosis pps1 gene, which contains an intein coding sequence, belongs to a conserved locus of seven open reading frames. In silico analyses indicated that the mature Pps1 protein is orthologous to the SufB protein of many organisms, a highly conserved component of the [Fe-S] cluster assembly and repair SUF (mobilization of sulfur) machinery. We showed that the mycobacterial pps1 locus constitutes an operon which encodes Suf-like proteins. Interactions between these proteins were demonstrated, supporting the functionality of the M. tuberculosis SUF system. The noticeable absence of any alternative [Fe-S] cluster assembly systems in mycobacteria is in agreement with the apparent essentiality of the suf operon in Mycobacterium smegmatis. Altogether, these results establish that Pps1, as a central element of the SUF system, could play an essential function for M. tuberculosis survival virtually through its implication in the bacterial resistance to iron limitation and oxidative stress. As such, Pps1 may represent an interesting molecular target for new antituberculous drugs.
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Affiliation(s)
- Gaëlle Huet
- Department of Molecular Mechanisms of Mycobacterial Infections, Institut de Pharmacologie et Biologie Structurale (UMR5089), C.N.R.S./Université Paul Sabatier Toulouse III, 205 Route de Narbonne, F-31077 Toulouse Cedex, France
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20
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Slavcev RA, Funnell BE. Identification and characterization of a novel allele of Escherichia coli dnaB helicase that compromises the stability of plasmid P1. J Bacteriol 2005; 187:1227-37. [PMID: 15687186 PMCID: PMC545633 DOI: 10.1128/jb.187.4.1227-1237.2005] [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] [Indexed: 11/20/2022] Open
Abstract
Bacteriophage P1 lysogenizes Escherichia coli cells as a plasmid with approximately the same copy number as the copy number of the host chromosome. Faithful inheritance of the plasmids relies upon proper DNA replication, as well as a partition system that actively segregates plasmids to new daughter cells. We genetically screened for E. coli chromosomal mutations that influenced P1 stability and identified a novel temperature-sensitive allele of the dnaB helicase gene (dnaB277) that replaces serine 277 with a leucine residue (DnaB S277L). This allele conferred a severe temperature-sensitive phenotype to the host; dnaB277 cells were not viable at temperatures above 34 degrees C. Shifting dnaB277 cells to 42 degrees C resulted in an immediate reduction in the rate of DNA synthesis and extensive cell filamentation. The dnaB277 allele destabilized P1 plasmids but had no significant influence on the stability of the F low-copy-number plasmid. This observation suggests that there is a specific requirement for DnaB in P1 plasmid maintenance in addition to the general requirement for DnaB as the replicative helicase during elongation.
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Affiliation(s)
- Roderick A Slavcev
- Department of Medical Genetics and Microbiology, University of Toronto, 1 Kings College Circle, Toronto, Ontario, Canada M5S 1A8
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21
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Soni RK, Mehra P, Choudhury NR, Mukhopadhyay G, Dhar SK. Functional characterization of Helicobacter pylori DnaB helicase. Nucleic Acids Res 2004; 31:6828-40. [PMID: 14627816 PMCID: PMC290263 DOI: 10.1093/nar/gkg895] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Helicobacter pylori causes gastric ulcer diseases and gastric adenocarcinoma in humans. Not much is known regarding DNA replication in H.pylori that is important for cell survival. Here we report the cloning, expression and characterization of H.pylori DnaB (HpDnaB) helicase both in vitro and in vivo. Among the DnaB homologs, only Escherichia coli DnaB has been studied extensively. HpDnaB showed strong 5' to 3' helicase and ATPase activity. Interestingly, H.pylori does not have an obvious DnaC homolog which is essential for DnaB loading on the E.coli chromosomal DNA replication origin (oriC). However, HpDnaB can functionally complement the E.coli DnaB temperature-sensitive mutant at the non-permissive temperature, confirming that HpDnaB is a true replicative helicase. Escherichia coli DnaC co-eluted in the same fraction with HpDnaB following gel filtration analysis suggesting that these proteins might physically interact with each other. It is possible that a functional DnaC homolog is present in H.pylori. The complete characterization of H.pylori DnaB helicase will also help the comparative analysis of DnaB helicases among bacteria.
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Affiliation(s)
- Rajesh K Soni
- Special Centre For Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
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22
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Lemonnier M, Ziegelin G, Reick T, Muñoz Gómez A, Díaz-Orejas R, Lanka E. Bacteriophage P1 Ban protein is a hexameric DNA helicase that interacts with and substitutes for Escherichia coli DnaB. Nucleic Acids Res 2003; 31:3918-28. [PMID: 12853607 PMCID: PMC165978 DOI: 10.1093/nar/gkg463] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Since the ban gene of bacteriophage P1 suppresses a number of conditionally lethal dnaB mutations in Escherichia coli, it was assumed that Ban protein is a DNA helicase (DnaB analogue) that can substitute for DnaB in the host replication machinery. We isolated and sequenced the ban gene, purified the product, and analysed the function of Ban protein in vitro and in vivo. Ban hydrolyses ATP, unwinds DNA and forms hexamers in the presence of ATP and magnesium ions. Since all existing conditionally lethal dnaB strains bear DnaB proteins that may interfere with the protein under study, we constructed a dnaB null strain by using a genetic set-up designed to provoke the conditional loss of the entire dnaB gene from E.coli cells. This novel tool was used to show that Ban restores the viability of cells that completely lack DnaB at 30 degrees C, but not at 42 degrees C. Surprisingly, growth was restored by the dnaB252 mutation at a temperature that is restrictive for ban and dnaB252 taken separately. This indicates that Ban and DnaB are able to interact in vivo. Complementary to these results, we demonstrate the formation of DnaB-Ban hetero-oligomers in vitro by ion exchange chromatography. We discuss the interaction of bacterial proteins and their phage-encoded analogues to fulfil functions that are essential to phage and host growth.
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Affiliation(s)
- Marc Lemonnier
- Departamento de Microbiología Molecular, Centro de Investigaciones Biológicas (CSIC), Velázquez 144, 28006 Madrid, Spain.
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23
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Hanada K, Yamashita T, Shobuike Y, Ikeda H. Role of DnaB helicase in UV-induced illegitimate recombination in Escherichia coli. J Bacteriol 2001; 183:4964-9. [PMID: 11489847 PMCID: PMC95370 DOI: 10.1128/jb.183.17.4964-4969.2001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To study the involvement of DNA replication in UV-induced illegitimate recombination, we examined the effect of temperature-sensitive dnaB mutations on illegitimate recombination and found that the frequency of illegitimate recombination was reduced by an elongation-deficient mutation, dnaB14, but not by an initiation-deficient mutation, dnaB252. This result indicates that DNA replication is required for UV-induced illegitimate recombination. In addition, the dnaB14 mutation also affected spontaneous or UV-induced illegitimate recombination enhanced by the recQ mutation. Nucleotide sequence analyses of the recombination junctions showed that DnaB-mediated illegitimate recombination is short homology dependent. Previously, Michel et al. (B. Michel, S. Ehrlich, and M. Uzest, EMBO J. 16:430--438, 1997) showed that thermal treatment of the temperature-sensitive dnaB8 mutant induces double-stranded breaks, implying that induction of illegitimate recombination occurs. To explain the discrepancy between the observations, we propose a model for DnaB function, in which the dnaB mutations may exhibit two types of responses, early and late responses, for double-stranded break formation. In the early response, replication forks stall at damaged DNA, resulting in the formation of double-stranded breaks, and the dnaB14 mutation reduces the double-stranded breaks shortly after temperature shift-up. On the other hand, in the late response, the arrested replication forks mediated by the dnaB8 mutation may induce double-stranded breaks after prolonged incubation.
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Affiliation(s)
- K Hanada
- The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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24
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Caspi R, Pacek M, Consiglieri G, Helinski DR, Toukdarian A, Konieczny I. A broad host range replicon with different requirements for replication initiation in three bacterial species. EMBO J 2001; 20:3262-71. [PMID: 11406602 PMCID: PMC150194 DOI: 10.1093/emboj/20.12.3262] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Plasmid RK2 is unusual in its ability to replicate stably in a wide range of Gram-negative bacteria. The replication origin (oriV) and a plasmid-encoded initiation protein (TrfA; expressed as 33 and 44 kDa forms) are essential for RK2 replication. To examine initiation events in bacteria unrelated to Escherichia coli, the genes encoding the replicative helicase, DnaB, of Pseudomonas putida and Pseudomonas aeruginosa were isolated and used to construct protein expression vectors. The purified proteins were tested for activity along with E.coli DnaB at RK2 oriV. Each helicase could be recruited and activated at the RK2 origin in the presence of the host-specific DnaA protein and the TrfA protein. Escherichia coli or P.putida DnaB was active with either TrfA-33 or TrfA-44, while P.aeruginosa DnaB required TrfA-44 for activation. Moreover, unlike the E.coli DnaB helicase, both Pseudomonas helicases could be delivered and activated at oriV in the absence of an ATPase accessory protein. Thus, a DnaC-like accessory ATPase is not universally required for loading the essential replicative helicase at a replication origin.
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Affiliation(s)
- Ron Caspi
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
| | - Marcin Pacek
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
| | - Giac Consiglieri
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
| | - Donald R. Helinski
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
| | - Aresa Toukdarian
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
| | - Igor Konieczny
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, CA 92093-0322, USA and Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland Present address: Pangene Corporation, 5500 Stewart Avenue, Fremont, CA 94538, USA Corresponding author e-mail:
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25
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Abstract
Replication fork arrest can cause DNA double-strand breaks (DSBs). These DSBs are caused by the action of the Holliday junction resolvase RuvABC, indicating that they are made by resolution of Holliday junctions formed at blocked forks. In this work, we study the homologous recombination functions required for RuvABC-mediated breakage in cells deficient for the accessory replicative helicase Rep or deficient for the main Escherichia coli replicative helicase DnaB. We show that, in the rep mutant, RuvABC-mediated breakage occurs in the absence of the homologous recombination protein RecA. In contrast, in dnaBts mutants, most of the RuvABC-mediated breakage depends on the presence of RecA, which suggests that RecA participates in the formation of Holliday junctions at forks blocked by the inactivation of DnaB. This action of RecA does not involve the induction of the SOS response and does not require any of the recombination proteins essential for the presynaptic step of homologous recombination, RecBCD, RecF or RecO. Consequently, our observations suggest a new function for RecA at blocked replication forks, and we propose that RecA acts by promoting homologous recombination without the assistance of known presynaptic proteins.
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Affiliation(s)
- M Seigneur
- Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, 78352 Jouy en Josas Cedex, France
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26
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Johnson SK, Bhattacharyya S, Griep MA. DnaB helicase stimulates primer synthesis activity on short oligonucleotide templates. Biochemistry 2000; 39:736-44. [PMID: 10651639 DOI: 10.1021/bi991554l] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DnaB helicase stimulated the second-order RNA primer synthesis activity of primase by over 5000-fold on DNA templates that were 23 nucleotides long. This template length is the same as the DnaB helicase thermodynamic binding site size [Jezewska, M. J., and Bujalowski, W. (1996) Biochemistry 35, 2117-2128]. This phenomenal stimulation was achieved by increasing the template affinity of primase by over 300-fold and increasing the catalytic rate by over 15-fold. It was necessary to determine the optimal amount of DnaB helicase to achieve this stimulation because helicase stimulation was cooperative at low concentration and inhibitory at high helicase concentration. The cooperative stimulation at low concentration indicated the presence of a time-dependent assembly step that preceded the active state. Besides stimulating primase activity, DnaB helicase also prevented primase from synthesizing RNA primers that were longer than the template sequence. In the absence of DnaB helicase, the majority of primers synthesized by primase were longer than the template and were named "overlong primers" [Swart, J. R., and Griep, M. A. (1995) Biochemistry 34, 16097-16106]. In contrast, the helicase-stimulated RNA primers were from 10 to 14 nucleotides in length with the 12-mer representing the majority of the total RNA primers produced. It was shown that DnaB helicase stabilized the open or single-stranded conformation of the template, which favored the synthesis of the template-length-dependent primers. In contrast, when primase acted alone, it stabilized the 3'-end hairpin conformation of the template so that the template's 3'-hydroxyl served as a "DNA primer" from which primase elongated to create the overlong primers.
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Affiliation(s)
- S K Johnson
- Department of Chemistry, Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0304, USA
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27
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Miller C, Cohen SN. Separate roles of Escherichia coli replication proteins in synthesis and partitioning of pSC101 plasmid DNA. J Bacteriol 1999; 181:7552-7. [PMID: 10601213 PMCID: PMC94213 DOI: 10.1128/jb.181.24.7552-7557.1999] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here that the Escherichia coli replication proteins DnaA, which is required to initiate replication of both the chromosome and plasmid pSC101, and DnaB, the helicase that unwinds strands during DNA replication, have effects on plasmid partitioning that are distinct from their functions in promoting plasmid DNA replication. Temperature-sensitive dnaB mutants cultured under conditions permissive for DNA replication failed to partition plasmids normally, and when cultured under conditions that prevent replication, they showed loss of the entire multicopy pool of plasmid replicons from half of the bacterial population during a single cell division. As was observed previously for DnaA, overexpression of the wild-type DnaB protein conversely stabilized the inheritance of partition-defective plasmids while not increasing plasmid copy number. The identification of dnaA mutations that selectively affected either replication or partitioning further demonstrated the separate roles of DnaA in these functions. The partition-related actions of DnaA were localized to a domain (the cell membrane binding domain) that is physically separate from the DnaA domain that interacts with other host replication proteins. Our results identify bacterial replication proteins that participate in partitioning of the pSC101 plasmid and provide evidence that these proteins mediate plasmid partitioning independently of their role in DNA synthesis.
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Affiliation(s)
- C Miller
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305-5120, USA
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28
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Sun W, Schoneich J, Godson GN. A mutant Escherichia coli primase defective in elongation of primer RNA chains. J Bacteriol 1999; 181:3761-7. [PMID: 10368151 PMCID: PMC93854 DOI: 10.1128/jb.181.12.3761-3767.1999] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Earlier we showed by affinity cross-linking of initiating substrates to Escherichia coli primase that one or more of the residues Lys211, Lys229, and Lys241 were involved in the catalytic center of the enzyme (A. A. Mustaev and G. N. Godson, J. Biol. Chem. 270:15711-15718, 1995). We now demonstrate by mutagenesis that only Lys241 but not Lys211 and Lys229 is part of the catalytic center. Primase with a mutation of Arg to Lys at position 241 (defined as K241R-primase) is almost unable to synthesize primer RNA (pRNA) on the single-stranded DNA-binding protein (SSB)/R199G4oric template. However, it is able to synthesize a pppApG dimer plus trace amounts of 8- to 11-nucleotide (nt) pRNA transcribed from the 5' CTG 3' pRNA initiation site on phage G4 oric DNA. The amount of dimer synthesized by K241R-primase is similar to that synthesized by the wild-type primase, demonstrating that the K241R mutant can initiate pRNA synthesis normally but is deficient in chain elongation. In the general priming system, the K241R-primase also can synthesize only the dimer and very small amounts of 11-nt pRNA. The results of gel retardation experiments suggested that this deficiency in pRNA chain elongation of the K241R mutant primase is unlikely to be caused by impairment of the DNA binding activity. The K241R mutant primase, however, can still prime DNA synthesis in vivo and in vitro.
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Affiliation(s)
- W Sun
- Biochemistry Department, New York University School of Medicine, New York, New York 10016, USA
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Saveson CJ, Lovett ST. Tandem repeat recombination induced by replication fork defects in Escherichia coli requires a novel factor, RadC. Genetics 1999; 152:5-13. [PMID: 10224240 PMCID: PMC1460591 DOI: 10.1093/genetics/152.1.5] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
DnaB is the helicase associated with the DNA polymerase III replication fork in Escherichia coli. Previously we observed that the dnaB107(ts) mutation, at its permissive temperature, greatly stimulated deletion events at chromosomal tandem repeats. This stimulation required recA, which suggests a recombinational mechanism. In this article we examine the genetic dependence of recombination stimulated by the dnaB107 mutation. Gap repair genes recF, recO, and recR were not required. Mutations in recB, required for double-strand break repair, and in ruvC, the Holliday junction resolvase gene, were synthetically lethal with dnaB107, causing enhanced temperature sensitivity. The hyperdeletion phenotype of dnaB107 was semidominant, and in dnaB107/dnaB+ heterozygotes recB was partially required for enhanced deletion, whereas ruvC was not. We believe that dnaB107 causes the stalling of replication forks, which may become broken and require repair. Misalignment of repeated sequences during RecBCD-mediated repair may account for most, but not all, of deletion stimulated by dnaB107. To our surprise, the radC gene, like recA, was required for virtually all recombination stimulated by dnaB107. The biochemical function of RadC is unknown, but is reported to be required for growth-medium-dependent repair of DNA strand breaks. Our results suggest that RadC functions specifically in recombinational repair that is associated with the replication fork.
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Affiliation(s)
- C J Saveson
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, USA
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Sun W, Godson GN. Synthesis of polyribonucleotide chains from the 3'-hydroxyl terminus of oligodeoxynucleotides by Escherichia coli primase. J Biol Chem 1998; 273:16358-65. [PMID: 9632699 DOI: 10.1074/jbc.273.26.16358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli primase synthesizes RNA primers on DNA templates for the initiation of DNA replication. The sole known activity of primase is to catalyze synthesis of short RNA chains de novo. We now report a novel activity of primase, namely that it can synthesize RNA from the 3'-hydroxyl terminus of a pre-existing oligodeoxynucleotide. The oligonucleotide-primed synthesis of RNA by primase occurs in both of the G4oric-specific priming system and the dnaB protein associated general priming system. This priming reaction of primase is verified by a number of biochemical methods, including inhibition by modified 3'-phosphate of oligonucleotides and deoxyribonuclease I and ribonuclease H cleavages. We also show that the primed RNA is an effective primer for the synthesis of DNA chain by E. coli DNA polymerase III holoenzyme. The significance of this finding to primases generating multimeric length RNA is discussed.
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Affiliation(s)
- W Sun
- Biochemistry Department, New York University Medical Center, New York, New York 10016, USA
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Stordal L, Maurer R. Defect in general priming conferred by linker region mutants of Escherichia coli dnaB. J Bacteriol 1996; 178:4620-7. [PMID: 8755893 PMCID: PMC178232 DOI: 10.1128/jb.178.15.4620-4627.1996] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The dnaB gene of Escherichia coli encodes a bifunctional primase accessory protein/helicase necessary for chromosomal replication. Monomers of DnaB comprise two trypsin-resistant domains connected by a 45-amino-acid linker. To investigate the role of the linker in the structure and function of DnaB, we have purified and characterized three DnaB mutant proteins having single amino acid substitutions in the linker. We find that the mutant proteins retain the two-domain structure and assemble into hexamers that may be less stable than hexamers formed by wild-type DnaB. These mutant hexamers have hydrodynamic properties slightly different from those of the wild type, suggestive of a more open structure. The mutant proteins had reduced or absent ability to stimulate primase and also exhibited slight alterations in ATPase activity compared with the wild type. We conclude that the linker region promotes primase-DnaB interaction, but this effect may be indirect. We propose a model involving repositioning of N-terminal domains to explain the properties of the mutant proteins.
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Affiliation(s)
- L Stordal
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4960, USA
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