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Biosca EG, Català-Senent JF, Figàs-Segura À, Bertolini E, López MM, Álvarez B. Genomic Analysis of the First European Bacteriophages with Depolymerase Activity and Biocontrol Efficacy against the Phytopathogen Ralstonia solanacearum. Viruses 2021; 13:v13122539. [PMID: 34960808 PMCID: PMC8703784 DOI: 10.3390/v13122539] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/11/2021] [Accepted: 12/14/2021] [Indexed: 12/28/2022] Open
Abstract
Ralstonia solanacearum is the causative agent of bacterial wilt, one of the most destructive plant diseases. While chemical control has an environmental impact, biological control strategies can allow sustainable agrosystems. Three lytic bacteriophages (phages) of R. solanacearum with biocontrol capacity in environmental water and plants were isolated from river water in Europe but not fully analysed, their genomic characterization being fundamental to understand their biology. In this work, the phage genomes were sequenced and subjected to bioinformatic analysis. The morphology was also observed by electron microscopy. Phylogenetic analyses were performed with a selection of phages able to infect R. solanacearum and the closely related phytopathogenic species R. pseudosolanacearum. The results indicated that the genomes of vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 range from 40,688 to 41,158 bp with almost 59% GC-contents, 52 ORFs in vRsoP-WF2 and vRsoP-WM2, and 53 in vRsoP-WR2 but, with only 22 or 23 predicted proteins with functional homologs in databases. Among them, two lysins and one exopolysaccharide (EPS) depolymerase, this type of depolymerase being identified in R. solanacearum phages for the first time. These three European phages belong to the same novel species within the Gyeongsanvirus, Autographiviridae family (formerly Podoviridae). These genomic data will contribute to a better understanding of the abilities of these phages to damage host cells and, consequently, to an improvement in the biological control of R. solanacearum.
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Affiliation(s)
- Elena G. Biosca
- Departamento de Microbiología y Ecología, Universitat de València (UV), 46100 Valencia, Spain; (J.F.C.-S.); (À.F.-S.); (E.B.); (B.Á.)
- Correspondence:
| | - José Francisco Català-Senent
- Departamento de Microbiología y Ecología, Universitat de València (UV), 46100 Valencia, Spain; (J.F.C.-S.); (À.F.-S.); (E.B.); (B.Á.)
- Centro de Investigación Príncipe Felipe, Unidad de Bioinformática y Bioestadística, 46012 Valencia, Spain
| | - Àngela Figàs-Segura
- Departamento de Microbiología y Ecología, Universitat de València (UV), 46100 Valencia, Spain; (J.F.C.-S.); (À.F.-S.); (E.B.); (B.Á.)
| | - Edson Bertolini
- Departamento de Microbiología y Ecología, Universitat de València (UV), 46100 Valencia, Spain; (J.F.C.-S.); (À.F.-S.); (E.B.); (B.Á.)
- Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 91540-000, Brazil
| | - María M. López
- Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Valencia, Spain;
| | - Belén Álvarez
- Departamento de Microbiología y Ecología, Universitat de València (UV), 46100 Valencia, Spain; (J.F.C.-S.); (À.F.-S.); (E.B.); (B.Á.)
- Departamento de Investigación Aplicada y Extensión Agraria, Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA), 28800 Alcalá de Henares, Spain
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Mitsunobu H, Zhu B, Lee SJ, Tabor S, Richardson CC. Flap endonuclease activity of gene 6 exonuclease of bacteriophage T7. J Biol Chem 2014; 289:5860-75. [PMID: 24394415 DOI: 10.1074/jbc.m113.538611] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Flap endonucleases remove flap structures generated during DNA replication. Gene 6 protein of bacteriophage T7 is a 5'-3'-exonuclease specific for dsDNA. Here we show that gene 6 protein also possesses a structure-specific endonuclease activity similar to known flap endonucleases. The flap endonuclease activity is less active relative to its exonuclease activity. The major cleavage by the endonuclease activity occurs at a position one nucleotide into the duplex region adjacent to a dsDNA-ssDNA junction. The efficiency of cleavage of the flap decreases with increasing length of the 5'-overhang. A 3'-single-stranded tail arising from the same end of the duplex as the 5'-tail inhibits gene 6 protein flap endonuclease activity. The released flap is not degraded further, but the exonuclease activity then proceeds to hydrolyze the 5'-terminal strand of the duplex. T7 gene 2.5 single-stranded DNA-binding protein stimulates the exonuclease and also the endonuclease activity. This stimulation is attributed to a specific interaction between the two proteins because Escherichia coli single-stranded DNA binding protein does not produce this stimulatory effect. The ability of gene 6 protein to remove 5'-terminal overhangs as well as to remove nucleotides from the 5'-termini enables it to effectively process the 5'-termini of Okazaki fragments before they are ligated.
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Affiliation(s)
- Hitoshi Mitsunobu
- From the Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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3
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Biswas SK, Chowdhury R, Das J. A 14-kilodalton inner membrane protein of Vibrio cholerae biotype e1 tor confers resistance to group IV choleraphage infection to classical vibrios. J Bacteriol 1992; 174:6221-9. [PMID: 1400172 PMCID: PMC207691 DOI: 10.1128/jb.174.19.6221-6229.1992] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Choleraphage phi 149 differentiates the two biotypes, classical and el tor, of Vibrio cholerae. This phage cannot replicate in V. cholerae biotype el tor cells because the concatemeric DNA intermediates produced are unstable and cannot be chased to mature phage DNA. A V. cholerae biotype el tor gene coding for a 14,000-Da inner membrane protein which destabilizes the concatemeric DNA intermediates by hindering their binding to the cell membrane has been identified. Presumably, a 22,000-Da V. cholerae biotype el tor protein might also have a role in conferring phage phi 149 resistance to cells belonging to the biotype el tor. A nucleotide sequence homologous to the 1.2-kb V. cholerae biotype el tor DNA coding for both the 14,000- and 22,000-Da proteins is present in all strains of classical vibrios but is not transcribed. The nucleotide sequence of the gene coding for the 14,000-Da protein has been determined.
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Affiliation(s)
- S K Biswas
- Biophysics Division, Indian Institute of Chemical Biology, Calcutta
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4
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Serwer P, Watson RH, Son M. Role of gene 6 exonuclease in the replication and packaging of bacteriophage T7 DNA. J Mol Biol 1990; 215:287-99. [PMID: 2170664 DOI: 10.1016/s0022-2836(05)80347-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
When bacteriophage T7 gene 6 exonuclease is genetically removed from T7-infected cells, degradation of intracellular T7 DNA is observed. By use of rate zonal centrifugation, followed by either pulsed-field agarose gel electrophoresis or restriction endonuclease analysis, in the present study, the following observations were made. (1) Most degradation of intracellular DNA requires the presence of T7 gene 3 endonuclease and is independent of DNA packaging; rapidly sedimenting, branched DNA accumulates when both the gene 3 and gene 6 products are absent. (2) A comparatively small amount of degradation requires packaging and occurs at both the joint between genomes in a concatemer and near the left end of intracellular DNA; DNA packaging is only partially blocked and end-to-end joining of genomes is not blocked in the absence of gene 6 exonuclease. (3) Fragments produced in the absence of gene 6 exonuclease are linear and do not further degrade; precursors of the fragments are non-linear. (4) Some, but not most, of the cleavages that produce these fragments occur selectively near two known origins of DNA replication. On the basis of these observations, the conclusion is drawn that most degradation that occurs in the absence of T7 gene 6 exonuclease is caused by cleavage at branches. The following hypothesis is presented: most, possibly all, of the extra branching induced by removal of gene 6 exonuclease is caused by strand displacement DNA synthesis at the site of RNA primers of DNA synthesis; the RNA primers, produced by multiple initiations of DNA replication, are removed by the RNase H activity of gene 6 exonuclease during a wild-type T7 infection. Observation of joining of genomes in the absence of gene 6 exonuclease and additional observations indicate that single-stranded terminal repeats required for concatamerization are produced by DNA replication. The observed selective shortening of the left end indicates that gene 6 exonuclease is required for formation of most, possibly all, mature left ends.
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Affiliation(s)
- P Serwer
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760
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5
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Abstract
The intercellular replication of the circularly permuted DNA of choleraphage phi 149 involves a concatemeric DNA structure with a size equivalent to six genome lengths. The synthesis of both monomeric and concatemeric DNAs during replication of phi 149 occurred in the cytoplasm. The concatemers served as the substrate for the synthesis of mature phage DNA, which was eventually packaged by a headful mechanism starting from a unique pac site in the concatemeric DNA. Packaging of DNA into phage heads involved binding of concatemeric DNA to the cell membrane. A scheme involving sequential packaging of five headfuls proceeding in the counterclockwise direction from the pac site is proposed. After infection under high-phosphate conditions, the concatemeric DNA intermediates were not formed, although synthesis of monomeric molecules was unaffected.
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Affiliation(s)
- R Chowdhury
- Biophysics Division, Indian Institute of Chemical Biology, Calcutta
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Serwer P, Watson RH, Hayes SJ. Multidimensional analysis of intracellular bacteriophage T7 DNA: effects of amber mutations in genes 3 and 19. J Virol 1987; 61:3499-509. [PMID: 2822958 PMCID: PMC255948 DOI: 10.1128/jvi.61.11.3499-3509.1987] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
By use of rate-zonal centrifugation, followed by either one- or two-dimensional agarose gel electrophoresis, the forms of intracellular bacteriophage T7 DNA produced by replication, recombination, and packaging have been analyzed. Previous studies had shown that at least some intracellular DNA with sedimentation coefficients between 32S (the S value of mature T7 DNA) and 100S is concatemeric, i.e., linear and longer than mature T7 DNA. The analysis presented here confirmed that most of this DNA is linear, but also revealed a significant amount of circular DNA. The data suggest that these circles are produced during DNA packaging. It is proposed that circles are produced after a capsid has bound two sequential genomes in a concatemer. The size distribution of the linear, concatemeric DNA had peaks at the positions of dimeric and trimeric concatemers. Restriction endonuclease analysis revealed that most of the mature T7 DNA subunits of concatemers were joined left end to right end. However, these data also suggest that a comparatively small amount of left-end to left-end joining occurs, possibly by blunt-end ligation. A replicating form of T7 DNA that had an S value greater than 100 (100S+ DNA) was also found to contain concatemers. However, some of the 100S+ DNA, probably the most branched component, remained associated with the origin after agarose gel electrophoresis. It has been found that T7 protein 19, known to be required for DNA packaging, was also required to prevent loss, probably by nucleolytic degradation, of the right end of all forms of intracellular T7 DNA. T7 gene 3 endonuclease, whose activity is required for both recombination of T7 DNA and degradation of host DNA, was required for the formation of the 32S to 100S molecules that behaved as concatemers during gel electrophoresis. In the absence of gene 3 endonuclease, the primary accumulation product was origin-associated 100S+ DNA with properties that suggest the accumulation of branches, primarily at the left end of mature DNA subunits within the 100S+ DNA.
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Affiliation(s)
- P Serwer
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760
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Lee D, Sadowski PD. In vitro recombination of bacteriophage T7 DNA detected by a direct physical assay. J Virol 1983; 48:647-53. [PMID: 6313964 PMCID: PMC255396 DOI: 10.1128/jvi.48.3.647-653.1983] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We developed a simple, direct, physical assay to detect genetic recombination of bacteriophage T7 DNA in vitro. In this assay two mature T7 DNA molecules, each having a unique restriction enzyme site, are incubated in the presence of a cell-free extract from T7-infected Escherichia coli cells. After extraction of the DNA, restriction enzyme digestion, and agarose gel electrophoresis, genetic recombination is detected by the appearance of a novel recombinant DNA band. Recombination frequencies as high as 13% have been observed. We used this assay to determine the genetic requirements for in vitro recombination. In agreement with results obtained previously with a biological assay, T7 recombination in vitro appears to proceed via two distinct pathways.
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9
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Mowat MR, Jachymczyk WJ, Hastings PJ, von Borstel RC. Repair of gamma-ray induced DNA strand breaks in the radiation-sensitive mutant rad18-2 of Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1983; 189:256-62. [PMID: 6343790 DOI: 10.1007/bf00337814] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The repair of gamma-ray induced DNA single and double-strand breaks was looked at in wild type and rad18-2 strains of the yeast Saccharomyces cerevisiae using sucrose gradient centrifugation. It was found that rad18-2 diploid cells could repair single and double-strand breaks induced by gamma-rays. It was also found that rad18-2 cells experienced a breakup of their DNA during post-irradiation incubation to a size smaller than seen in cells just receiving irradiation. This breakup of DNA in rad18-2 cells is not degradation due to cell death since wild type cells irradiated to similar low survival levels do not show this breakup of DNA with 8 h incubation. The breakup of DNA in rad18-2 cells is not due to replication gaps being formed by synthesis on a damaged template since treatment of rad18-2 a mating type cells with alpha factor, to prevent initiation of DNA synthesis, does not prevent breakup of the DNA.
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10
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Lee DD, Sadowski PD. Bacteriophage T7 defective in the gene 6 exonuclease promotes site-specific cleavages of T7 DNA in vivo and in vitro. J Virol 1982; 44:235-40. [PMID: 7143567 PMCID: PMC256257 DOI: 10.1128/jvi.44.1.235-240.1982] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Site-specific cleavages of intracellular DNA were demonstrated in bacteriophage T7 6am-infected cells. The sites of the cleavages were located at 46.8 and 68.7% (1% of the T7 DNA length = 400 base pairs) from the left end of the T7 genome. These cleavages required the products of genes 3 (endonuclease), 4 (DNA primase), and 5 (DNA polymerase). However, the product of gene 6 (exonuclease) must be absent. Site-specific cleavage was also shown to occur in vitro in extracts of T7 6am-infected cells, although at a different site: 82.8% from the left end of the T7 genome.
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11
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12
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Francke B, Garrett B. The effect of a temperature-sensitive lesion in the alkaline DNase of herpes simplex virus type 2 on the synthesis of viral DNA. Virology 1982; 116:116-27. [PMID: 6278703 DOI: 10.1016/0042-6822(82)90407-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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13
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Smith RD, Miller RC. Replication and plasmid-bacteriophage recombination. I. Marker rescue analysis. Virology 1981; 115:223-36. [PMID: 7032053 DOI: 10.1016/0042-6822(81)90106-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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14
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Walling L, Christensen JR. The synthesis of coliphage T1 DNA: studies on the roles of T1 genes 1, 2, and 4. Virology 1981; 114:309-18. [PMID: 7292982 DOI: 10.1016/0042-6822(81)90213-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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15
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Fujisawa H, Yamagishi M, Matsuo-Kato H, Minagawa T. Purification of DNA-binding proteins of bacteriophage T3 and heir role in in vitro packaging of phage T3 DNA. Virology 1980; 105:480-9. [PMID: 6893505 DOI: 10.1016/0042-6822(80)90048-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Fujisawa H, Yamagishi M, Minagawa T. In vitro formation of the concatemeric DNA of bacteriophage T3 and its biological activity in the in vitro packaging reaction. Virology 1980; 101:327-34. [PMID: 7361452 DOI: 10.1016/0042-6822(80)90448-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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19
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Farber MB, Ehrlich M. Bacteriophage XP-12-induced exonuclease which preferentially hydrolyzes nicked DNA. J Virol 1980; 33:733-8. [PMID: 6251244 PMCID: PMC288598 DOI: 10.1128/jvi.33.2.733-738.1980] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
An exonuclease has been partially purified from XP-12-infected Xanthomonas oryzae which is not found in uninfected X. oryzae. Although both the phage-induced exonuclease and the major host exonucleolytic DNase released 5'-mononucleotides, these enzymes differed in their chromatographic behavior, pH optimum, salt inhibition, and heat sensitivity. These two exonucleases preferred different substrates. Nicked native DNA was the best substrate for the phage-induced enzyme, whereas denatured DNA was the best substrate for the host enzyme. Also, the host enzyme had a significant preference for denatured or nicked, normal cytosine-containing DNA (e.g., X. oryzae or T7 DNA) over similarly denatured or nicked 5-methylcytosine-rich DNA (namely, XP-12DNA), whereas the phage-induced enzyme hydrolyzed both types of DNA equally well.
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20
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Yamagishi M, Fujisawa H, Yamagishi H, Minagawa T. Purification of gene 6 product of bacteriophage T3 and its role in vitro DNA packaging. Virology 1980; 100:382-9. [PMID: 7352372 DOI: 10.1016/0042-6822(80)90529-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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21
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Abstract
A system capable of in vitro packaging of exogenous bacteriophage T7 DNA has been used to monitor the biological activity of DNA replicated in vitro. This system has been used to follow the effects of UV radiation on in vitro replication and recombination. During the in vitro replication process, a considerable exchange of genetic information occurs between T7 DNA molecules present in the reaction mixture. This in vitro recombination is reflected in the genotype of the T7 phage produced after in vitro encapsulation; depending on the genetic markers selected, recombinants can comprise nearly 20% of the total phage production. When UV-irradiated DNA is incubated in this system, the amount of in vitro synthesis is reduced and the total amount of viable phage produced after in vitro packaging is diminished. In vitro recombination rates are also lower when the participating DNA molecules have been exposed to UV. However, biochemical and genetic measurements confirmed that there is little or no transfer of pyrimidine dimers from irradiated DNA into undamaged molecules.
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22
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Roberts L, Sheldon R, Sadowski PD. Genetic recombination of bacteriophage T7 DNA in vitro. IV. Asymmetry of recombination frequencies caused by polarity of DNA packaging. Virology 1978; 89:252-61. [PMID: 685180 DOI: 10.1016/0042-6822(78)90057-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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23
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Masker WE, Kuemmerle NB, Allison DP. In vitro packaging of bacteriophate T7 DNA synthesized in vitro. J Virol 1978; 27:149-63. [PMID: 691109 PMCID: PMC354148 DOI: 10.1128/jvi.27.1.149-163.1978] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
An in vitro DNA packaging system was used to encapsulate T7 DNA that had been synthesized by extracts prepared from gently lysed Escherchia coli infected with bacteriophage T7 carrying amber mutations in gene 3 or in both genes 3 and 6. Isopycnic centrifugation of density-labeled wild-type DNA was employed in an effort to separate product from template; suppressor-free indicator bacteria were used to eliminate contributions from endogenous DNA or contaminating phage. Additional controls indicated that fragmented DNA is packaged in vitro only with very low efficiency and that the frequency of recombination during packaging is too low to affect interpretation of these experiments. T7 DNA replicated by extracts prepared using T7 mutants deficient in both genes 3 and 6 could be packaged in vitro with an efficiency comparable to that found when highly purified virion T7 DNA was used. When T7 deficient in the gene 3 endonuclease but with normal levels of the gene 6 exonuclease was used, fast-sedimentingconcatemer-like DNA structures were formed during in vitro DNA synthesis. Electron microscopy revealed many branched and highly complex DNA structures formed during this reaction. This concatemer-like DNA was encapsulated in vitro with an efficiency significantly greater than that found for DNA the length of a single T7 genome.
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Benbasat JA, Burck KB, Miller RC. Superinfection exclusion and lack of conservative transfer of bacteriophage T7 DNA. Virology 1978; 87:164-71. [PMID: 664250 DOI: 10.1016/0042-6822(78)90168-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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26
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Yamada Y, Silnutzer J, Nakada D. Mutant of Escherichia coli which blocks T7 bacteriophage assembly: accumulation of short T7 DNA. J Mol Biol 1978; 121:95-111. [PMID: 351190 DOI: 10.1016/0022-2836(78)90264-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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27
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Dreiseikelmann B, Wackernagel W. The terminal redundant regions of bacteriophage T7 DNA: their necessity for phage production studied by the infectivity of T7 DNA after modification by various exonucleases. MOLECULAR & GENERAL GENETICS : MGG 1978; 159:321-8. [PMID: 345101 DOI: 10.1007/bf00268269] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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28
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Shinozaki K, Okazaki T. RNA-linked nascent DNA pieces in T7 phage-infected Escherichia coli cells. I. Role of gene 6 exonuclease in removal of the linked RNA. MOLECULAR & GENERAL GENETICS : MGG 1977; 154:263-7. [PMID: 337106 DOI: 10.1007/bf00571281] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The presence of RNA-linked nascent DNA pieces in T7 phage-infected Escherichia coli cells has been shown by the selective degradation of the 5'-hydroxyl-terminated nascent DNA, produced by alkali or RNase treatment, with spleen exonuclease. At 43 degrees C, the proportion of RNA-linked DNA pieces in nascent short dna is 50 to 60% in T7 ts136 (ts mutant of gene 6) phage-infected E. coli, whereas that in T7 wild-type phage-infected cells is less than 6%. Joining of the nascent pieces is greatly retarded in T7 ts136-infected E. coli temperature sensitive polA mutants at 43 degrees C. These results suggest that gene 6 exonuclease plays a role in removal of the linked RNA during the discontinuous replication of T7 DNA.
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29
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Zabrovitz S, Segev N, Cohen G. Growth of bacteriophage P1 in recombination-deficient hosts of Escherichia coli. Virology 1977; 80:233-48. [PMID: 329556 DOI: 10.1016/s0042-6822(77)80001-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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30
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Vlachopoulou PJ, Sadowksi PD. Genetic recombination of bacteriophage T7 DNA in vitro III. A physical assay for recombinant DNA. Virology 1977; 78:203-15. [PMID: 860400 DOI: 10.1016/0042-6822(77)90092-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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31
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Sadowski PD. Genetic recombination of bacteriophage T7 DNA in vitro. II. Further properties of the in vitro recombination-packaging reaction. Virology 1977; 78:192-202. [PMID: 860399 DOI: 10.1016/0042-6822(77)90091-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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32
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Paetkau V, Langman L, Bradley R, Scraba D, Miller RC. Folded, concatenated genomes as replication intermediates of bacteriophage T7 DNA. J Virol 1977; 22:130-41. [PMID: 853564 PMCID: PMC515693 DOI: 10.1128/jvi.22.1.130-141.1977] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A complex form of bacteriophage T7 DNA, containing up to several hundred phage equivalents of DNA, arises during replication of T7. The complex was stable to treatment with ionic detergent, Pronase, and phenol. The complex form normally exists for only a short time, corresponding to the phase of rapid T7 DNA synthesis. It is then converted to shorter molecules, both concatemers and unit-size DNA. The complex was stable up to the temperature of denaturation of the bihelix. It consisted of a series of loops amanating from a dense central core, as shownby electron microscopy. The complex form is similar to the relaxed Escherichia coli folded chromosome ('nucleoid'). The loops contained an average of 0.7 to 0.8 phage equivalent of DNA. During infection by phage with an amber mutation in gene 3 (endonuclease), formation of the complex occurred normally, but its maturation to unit-size DNA blocked. Before treatment with phenol, the complex contained short fragments of newly replicated DNA. These were released as single-stranded pieces during phenol treatment. A pathway for T7 DNA replication is indicated in which the flow of material is from unit-size DNA to linear concatemers to the complex form, and then back to unit-size DNA by way of linear concatemers.
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Lee M, Miller RC, Scraba D, Paetkau V. The essential role of bacteriophage T7 endonuclease (gene 3) in molecular recombination. J Mol Biol 1976; 104:883-8. [PMID: 785017 DOI: 10.1016/0022-2836(76)90189-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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