Gamma delta transposase and integration host factor bind cooperatively at both ends of gamma delta.

Wiater, Lawrence A.; Grindley, Nigel D. F.

doi:10.1002/j.1460-2075.1988.tb03024.x

Cited by 54 publications

(44 citation statements)

References 28 publications

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“…Thus, the timing of transposition of certain elements is at least partially correlated with the cell replication cycle. Other biochemical and genetic studies have identified host factors, such as integration host factor, histone-like nucleoid structuring protein, and Hu, as playing an important-but not essentialrole in transposition of many elements (30,41,51,52,55). Indeed, the observation that these nucleoid-associated proteins can influence both transposition and site-specific recombination reinforces the proposal that these proteins communicate cellular status to the recombination machinery (6,53).…”

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confidence: 78%

Genetic Evidence that GTP Is Required for Transposition of IS 903 and Tn 552 in Escherichia coli

et al. 2005

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Surprisingly little is known about the role of host factors in regulating transposition, despite the potentially deleterious rearrangements caused by the movement of transposons. An extensive mutant screen was therefore conducted to identify Escherichia coli host factors that regulate transposition. An E. coli mutant library was screened using a papillation assay that allows detection of IS903 transposition events by the formation of blue papillae on a colony. Several host mutants were identified that exhibited a unique papillation pattern: a predominant ring of papillae just inside the edge of the colony, implying that transposition was triggered within these cells based on their spatial location within the colony. These mutants were found to be in pur genes, whose products are involved in the purine biosynthetic pathway. The transposition ring phenotype was also observed with Tn552, but not Tn10, establishing that this was not unique to IS903 and that it was not an artifact of the assay. Further genetic analyses of purine biosynthetic mutants indicated that the ring of transposition was consistent with a GTP requirement for IS903 and Tn552 transposition. Together, our observations suggest that transposition occurs during late stages of colony growth and that transposition occurs inside the colony edge in response to both a gradient of exogenous purines across the colony and the developmental stage of the cells.Transposons are defined as distinct regions of DNA that have the ability to move from one genomic location to another, a process mediated by element-encoded transposases (8, 9). While the main focus of transposition research has been in determining the detailed mechanisms of transposition, relatively little attention has been paid to how transposition is regulated in vivo or the in vivo requirements for the process (35). Transposon movement can result in gene inactivation (by insertional inactivation or deletion) or activation (by creation or introduction of promoters upstream of genes). In addition, intramolecular transposition can result in extensive DNA rearrangements, including deletions, inversions, and duplications of chromosome segments; these events are thought to play an important role in facilitating genome evolution (7-9). As the consequences of transposition can be either dire or favorable for the host organism, it is intuitive that the host has the capability to regulate this process. There are multiple examples of how transposons regulate their own movement, but very little work has focused on the role played by the host in regulating transposition. To address this, we have generated an insertion mutant library of Escherichia coli, which we have used to screen for host genes involved in regulation of IS903 transposition (E. Twiss, A. Coros, N. Tavakoli, and K. M. Derbyshire, unpublished data).The first comprehensive genetic screen for host mutants affecting transposition was carried out in 1985; it revealed a role for dam methylation in decreasing the rate of IS10, IS903, and IS50 transposi...

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confidence: 78%

Genetic Evidence that GTP Is Required for Transposition of IS 903 and Tn 552 in Escherichia coli

et al. 2005

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“…IHF modulates Tn10 transposition in vivo and in vitro; IHF stimulates Tn10 excision and forces transposon end-target DNA interactions into a constrained pathway that yields only unknotted intratransposon inversion circles (3,54). IHF binds to the ends of ␥␦, a Tn3 family element, cooperatively with transposase and stimulates transpositional immunity of ␥␦ (67,68). Fis is required for various site-specific recombination systems, and HU and IHF act in some of these systems as well (for a review, see reference 12).…”

Section: Discussionmentioning

confidence: 99%

Involvement of H-NS in Transpositional Recombination Mediated by IS 1

et al. 2001

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IS1, the smallest active transposable element in bacteria, encodes a transposase that promotes inter-and intramolecular transposition. Host-encoded factors, e.g., histone-like proteins HU and integration host factor (IHF), are involved in the transposition reactions of some bacterial transposable elements. Host factors involved in the IS1 transposition reaction, however, are not known. We show that a plasmid with an IS1 derivative that efficiently produces transposase did not generate miniplasmids, the products of intramolecular transposition, in mutants deficient in a nucleoid-associated DNA-binding protein, H-NS, but did generate them in mutants deficient in histone-like proteins HU, IHF, Fis, and StpA. Nor did IS1 transpose intermolecularly to the target plasmid in the H-NS-deficient mutant. The hns mutation did not affect transcription from the indigenous promoter of IS1 for the expression of the transposase gene. These findings show that transpositional recombination mediated by IS1 requires H-NS but does not require the HU, IHF, Fis, or StpA protein in vivo. Gel retardation assays of restriction fragments of IS1-carrying plasmid DNA showed that no sites were bound preferentially by H-NS within the IS1 sequence. The central domain of H-NS, which is involved in dimerization and/or oligomerization of the H-NS protein, was important for the intramolecular transposition of IS1, but the N-and C-terminal domains, which are involved in the repression of certain genes and DNA binding, respectively, were not. The SOS response induced by the IS1 transposase was absent in the H-NSdeficient mutant strain but was present in the wild-type strain. We discuss the possibility that H-NS promotes the formation of an active IS1 DNA-transposase complex in which the IS1 ends are cleaved to initiate transpositional recombination through interaction with IS1 transposase.IS1 is an insertion element present in chromosomes and plasmids of enteric bacteria (for a review, see reference 38). IS1 (768 bp long) carries imperfect terminal inverted repeats (IRL and IRR) that are about 30 bp long (17,40). IS1 mediates the formation of cointegrates between the IS1-carrying plasmid and a target plasmid in which two copies of IS1 are duplicated at the two junctions in direct orientation (10,39). This element encodes two open reading frames, insA and BЈ-insB (16,32,33). Transcription occurs from a promoter present in the left-terminal region (IRL) preceding insA (31). A translational frameshift occurs in the Ϫ1 direction at the AAAAAAC (A 6 C) sequence in the overlapping region between the two open reading frames, producing the InsA-BЈ-InsB transframe protein, IS1 transposase (7, 49). Unless frameshifting occurs, IS1 produces InsA protein from insA which can bind to the IRs (51, 74) and inhibits transposition (30,75). An IS1 mutant (IS1-31) with a single adenine insertion at the frameshifting site efficiently produces transposase and therefore can frequently transpose and mediate cointegration (49). The plasmid with this IS1 mutant generates min...

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“…Reports suggest that IHF can stimulate translation initiation (35) and transcription initiation (6,17,18,24,25,48) and elongation (59). In some of these systems (17,24,57), and in other processes (4,44,47), IHF has been found to alter DNA structure and influence the function of other DNA-binding proteins (25,47,61). Therefore, the negative effect of IHF on ompB transcription may be more complex than a simple model of direct interaction between IHF and RNA polymerase.…”

Section: Methodsmentioning

confidence: 99%

Integration host factor binds specifically to multiple sites in the ompB promoter of Escherichia coli and inhibits transcription

1991

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Escherichia coli integration host factor (IHF) is a DNA-binding protein that participates in gene regulation, site-specific recombination, and other processes in E. coli and some of its bacteriophages and plasmids. In the present study, we showed that IHF is a direct negative effector of the ompB operon of E. coli. Gel retardation experiments and DNase I footprinting studies revealed that IHF binds to three sites in the ompB promoter region. In vitro transcription from ompB promoter fragments was specifically blocked by IHF. In vivo experiments showed that IHF is a negative effector of ompB expression in growing cells. Analysis of IHF binding site mutations strongly suggested that IHF binding in the ompB promoter region is necessary for the negative effects seen in vivo.

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Gamma delta transposase and integration host factor bind cooperatively at both ends of gamma delta.

Cited by 54 publications

References 28 publications

Genetic Evidence that GTP Is Required for Transposition of IS 903 and Tn 552 in Escherichia coli

Genetic Evidence that GTP Is Required for Transposition of IS 903 and Tn 552 in Escherichia coli

Involvement of H-NS in Transpositional Recombination Mediated by IS 1

Integration host factor binds specifically to multiple sites in the ompB promoter of Escherichia coli and inhibits transcription

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