T7 endonuclease I resolves Holliday junctions formed<i>in vitro</i>by RecA protein

Müller, Berndt; Jones, Christine; West, Stephen C.

doi:10.1093/nar/18.19.5633

Cited by 17 publications

(13 citation statements)

References 19 publications

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“…However, in vivo studies have indicated a role for the gene 3 endonuclease in general homologous recombination in T7 (7,12,22,26,41). The properties of the gene 3 endonuclease are compatible with a role in facilitating resolution of the Holliday junctions formed during recombination (1,18). A trivial explanation for the apparent lack of dependence on gene 3 derives from the likelihood that some gene 3 endonuclease is probably present in these extracts because of wild-type contamination in preparations of the gene 3-deficient phage used to make extracts or because of amber read-through.…”

Section: Resultsmentioning

confidence: 99%

In vitro repair of double-strand breaks accompanied by recombination in bacteriophage T7 DNA

Masker

1992

J Bacteriol

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A double-strand break in a bacteriophage T7 genome significantly reduced the ability of that DNA to produce viable phage when the DNA was incubated in an in vitro DNA replication and packaging system. When a homologous piece of T7 DNA (either a restriction fragment or T7 DNA cloned into a plasmid) that was by itself unable to form a complete phage was included in the reaction, the break was repaired to the extent that many more viable phage were produced. Moreover, repair could be completed even when a gap of about 900 nucleotides was put in the genome by two nearby restriction cuts. The repair was accompanied by acquisition of a genetic marker that was present only on the restriction fragment or on the T7 DNA cloned into a plasmid. These data are interpreted in light of the double-strand gap repair mode of recombination.A popular model for repair of a double-strand break, based upon the recombination of the broken molecule with an intact portion of a homologous region of duplex DNA, is supported by considerable experimental evidence (23,(36)(37)(38)(39). In this model, the double-strand break is first widened to form a gap so that each strand of both pieces of the broken DNA can establish base pairing with complementary strands on the intact homolog. Repairlike DNA synthesis with the unbroken donor molecule as template would fill the gap. The recipient DNA molecule which had suffered a strand break thereby acquires genetic information present on the donor molecule. There is also considerable evidence that phage T4 recombination is stimulated at the ends of DNA molecules (17). This paper describes repair of a double-strand break in the highly recombinogenic (34, 35) bacteriophage T7. T7 recombination is independent of the host RecA recombinase (21), and T7 is known to inactivate exonuclease V, the product of the Escherichia coli recBCD genes (43). It has been suggested that T7 single-strand-binding protein may play a central role in promoting the annealing of complementary single strands of phage DNA (28). T7 endonuclease I (gene 3), helicase-primase (gene 4), DNA polymerase (gene 5), and exonuclease (gene 6) play roles in T7 recombination (5,7,11,12,22,26,40,41). The precise molecular mechanisms responsible for T7 recombination are poorly understood. Therefore, possible involvement of strand breaks in this phage's recombination mechanism(s) remains an open question.Other workers have reported in vitro recombination of T7 DNA (6,9,(25)(26)(27)(28)(29)42 MATERIALS AND METHODSBacteria and phage. Bacteria used in this study were the wild-type, suppressor-free E. coli strain W3110, E. coli TB-1 [ara A(lac-proAB) rpsL hsdR D80 lacZM15], the suppressorfree Shigella sonnei strain ShD2 371-48, and S. sonnei Sh3-18, which contains an amber suppressor. Both S. sonnei strains and the ss-("suicide in Shigella") T7 strain were gifts from R. Hausmann. Wild-type T7 and T7 with amber mutation am29 in gene 3, am20 in gene 4, am28 in gene 5, or am147 in gene 6 were from W. Studier. Our previous studies had shown that a single A-...

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Section: Resultsmentioning

confidence: 99%

In vitro repair of double-strand breaks accompanied by recombination in bacteriophage T7 DNA

Masker

1992

J Bacteriol

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“…T7 endonuclease I cleaves cruciform DNA 2-4 bp away from the single-stranded loop and base regions (25). 2 In branched dsDNA, cleavage by T7 endonuclease I and other singlestranded endonucleases occurs 1-10 bp away from the branch point at sites that do not conform to a strict pattern with respect to distance from the branch point, strand, or sequence preference (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). The same pattern emerges from probing synthetic, mismatched DNA, where strand scission occurs at variable lengths from the mismatch (36).…”

Section: Discussionmentioning

confidence: 99%

A Shared, Non-canonical DNA Conformation Detected at DNA/Protein Contact Sites and Bent DNA in the Absence of Supercoiling or Cognate Protein Binding

Economides

Everdeen²,

Panayotatos

1996

Journal of Biological Chemistry

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A hybrid protein (H144), consisting of Lac repressor and T7 endonuclease I, binds at the lac operator and cleaves relaxed double-stranded DNA at distal but distinct sites. These sites are shown here to coincide with a bacterial promoter, a phage T7 promoter, a site for gyrase and intrinsically bent DNA. The targets do not seem to share a particular DNA sequence, and in bent DNA, cleavage occurs at the physical center rather than at the common A-tracts. These results indicate that protein contact sites and intrinsic bends assume a non-canonical conformation in the absence of supercoiling or cognate protein binding. This feature may serve as a recognition signal or facilitate protein binding to initiate transcription and recombination.

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“…This is accompanied by a localized distortion of the base pairs at the point of strand exchange, which provides a strong contrast to the structure of the T4 endo VII -HJ complex. In the presence of Mg 2þ or Mn 2þ , T7 endo I catalyzes the endonucleolytic cleavage of (1) secondary structures that form in ssDNA, (2) supercoiled plasmid DNA, and (3) various branched double-stranded DNA (ds DNA), substrates, including cruciforms, HJs, threeway junctions, and Y-shaped structures (Center and Richardson 1970;Sadowski 1971;de Massy et al 1987;Müller et al 1990;Picksley et al 1990;Parkinson and Lilley 1997). T7 endo I shows a preference for cleavage between two pyrimidine residues (Picksley et al 1990).…”

Section: T7 Endonuclease Imentioning

confidence: 99%

Holliday Junction Resolvases

Wyatt

West

2014

Cold Spring Harbor Perspectives in Biology

179

194

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Four-way DNA intermediates, called Holliday junctions (HJs), can form during meiotic and mitotic recombination, and their removal is crucial for chromosome segregation. A group of ubiquitous and highly specialized structure-selective endonucleases catalyze the cleavage of HJs into two disconnected DNA duplexes in a reaction called HJ resolution. These enzymes, called HJ resolvases, have been identified in bacteria and their bacteriophages, archaea, and eukaryotes. In this review, we discuss fundamental aspects of the HJ structure and their interaction with junction-resolving enzymes. This is followed by a brief discussion of the eubacterial RuvABC enzymes, which provide the paradigm for HJ resolvases in other organisms. Finally, we review the biochemical and structural properties of some well-characterized resolvases from archaea, bacteriophage, and eukaryotes.

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T7 endonuclease I resolves Holliday junctions formedin vitroby RecA protein

Cited by 17 publications

References 19 publications

In vitro repair of double-strand breaks accompanied by recombination in bacteriophage T7 DNA

In vitro repair of double-strand breaks accompanied by recombination in bacteriophage T7 DNA

A Shared, Non-canonical DNA Conformation Detected at DNA/Protein Contact Sites and Bent DNA in the Absence of Supercoiling or Cognate Protein Binding

Holliday Junction Resolvases

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