Stabilization of bacteriophage Mu repressor‐operator complexes by the <i>Escherichia coli</i> integration host factor protein

Gama, M.-J.; Toussaint, Ariane; Higgins, N. Patrick

doi:10.1111/j.1365-2958.1992.tb00896.x

Cited by 31 publications

(22 citation statements)

References 37 publications

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“…11,+6) vir3061 (-23,+13) proposed that binding of IHF to its cognate site located between O1 and 02 provides the right conformation for optimal repressor binding (Vogel et aI., 1991). This was confirmed by both in vivo and in vitro experiments which showed that IHF increases repression by repressor in vivo and facilitates repressor binding to the operators in vitro (Gama, Toussaint & Higgins, 1992;Alazard, B6termier & Chandler, 1992). The host H-NS protein, another nucleoid associated histone-like protein, has similar effects on repression and repressot binding as IHE Its exact mechanism of action is unknown and although it has been proposed that H-NS acts through protein-protein interactions with repressor (Falconi et al, 1991), the possibility remains open that H-NS binds DNA in the operator region, as it does for instance in the rrn promoters (Tippner et al, 1994).…”

Section: Lysogenysupporting

confidence: 75%

Regulation of bacteriophage Mu transposition

et al. 1994

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Bacteriophage Mu is a transposon and a temperate phage which has become a paradigm for the study of the molecular mechanism of transposition. As a prophage, Mu has also been used to study some aspects of the influence of the host cell growth phase on the regulation of transposition. Through the years several host proteins have been identified which play a key role in the replication of the Mu genome by successive rounds of replicative transposition as well as in the maintenance of the repressed prophage state. In this review we have attempted to summarize all these findings with the purpose of emphasizing the benefit the virus and the host cell can gain from those phage-host interactions.

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Section: Lysogenysupporting

confidence: 75%

Regulation of bacteriophage Mu transposition

et al. 1994

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“…Binding of IHF to the early operator region of Mu (39,69) can influence transcriptional control in different ways. By stabilizing the interaction of the repressor with sites 01 and 02, it may favor lysogeny (19,20), whereas in the absence of c (i.e., during lytic growth), it stimulates early transcription (23,39). In addition, IHF binding to the IAS directly stimulates in vitro transposition of a substrate with suboptimal supercoiling levels (62,64).…”

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confidence: 99%

Involvement of Escherichia coli FIS protein in maintenance of bacteriophage mu lysogeny by the repressor: control of early transcription and inhibition of transposition

et al. 1993

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The Escherichia coli FIS (factor for inversion stimulation) protein has been implicated in assisting bacteriophage Mu repressor, c, in maintaining the lysogenic state under certain conditions. In a fis strain, a temperature-inducible Mucts62 prophage is induced at lower temperatures than in a wild-type host (M. Betermier, V. Lefrere, C. Koch, R. Alazard, and M. Chandler, Mol. Microbiol. 3:459-468, 1989

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“…IHF plays an architectural role in the formation of various nucleoprotein complexes involved in different phenomena such as transcription activation, transcription repression, site-specific recombination, transposition, initiation of DNA replication, and plasmid partition. Binding of IHF could create a loop which stabilizes interaction of Roi with its binding site(s): this is reminiscent of the stabilization of the Mu repressor interaction with its operator (1,12). Interestingly, we noted the presence of an IHF binding site in the gene that encodes the related P1 Ant1 protein (from nt 855 to 867 in the sequence reported by Heisig et al [17]).…”

Section: Discussionmentioning

confidence: 75%

“…We speculated that IHF could bind the ihf site within the roi gene and possibly stabilize the interaction of the DNA-binding Roi protein with its target DNA, as happens in Mu repressor-operator interaction (1,12). The target of the Roi protein might then be located near the ihf site.…”

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Phage HK022 Roi protein inhibits phage lytic growth in Escherichia coli integration host factor mutants

Clerget

Boccard

1996

J Bacteriol

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Temperate coliphage HK022 requires integration host factor (IHF) for lytic growth. The determinant responsible for this requirement was identified as a new gene (roi) located between genes P and Q. This gene encodes a DNA-binding protein (Roi) containing a helix-turn-helix motif. We have shown that Roi binds a site within its own gene that is closely linked to an IHF binding site. By gel retardation experiments, we have found that IHF binding stabilizes the interaction of Roi with its gene. We have isolated three independent phage mutants that are able to grow on an IHF ؊ host. They carry different mutations scattered in the roi gene and specifying single amino-acid changes. The interactions of all three Roi mutant proteins with the Roi binding site differed from that of the wild type. Roi displays strong similarities, in its C-terminal half, to two putative DNA-binding proteins of bacteriophage P1: Ant1 and KilA. The mode of action of the Roi protein and the possibility that IHF is modulating the expression and/or the action of Roi are discussed.HK022 is a temperate coliphage, a member of the lambdoid family, to which belong phages lambda, 80, 21, P22, and 434. These phages share a common genetic organization which allows the exchange of information, genes or blocks of genes, among them (6). Some genes are always required for the phage to form plaques, while other genes are not essential for phage development in standard hosts but can play important roles in certain circumstances. These have been called accessory genes (6). Some accessory genes are carried by some of the phages in the family but not by others. It is known that phage lambda can form plaques in a host deficient in the integration host factor (IHF). In contrast, HK022 (8) and 80 (20, 21) do not form plaques in a host deficient in IHF. The basis of the HK022 IHF requirement was unknown and is the subject of this study.IHF is a small DNA-binding protein belonging to the family of prokaryotic histone-like proteins. It has remarkable DNAbinding properties: unlike most histone-like proteins, it binds preferentially to specific sites in DNA, makes most of its sequence-specific contacts in the minor groove of DNA, and is one of the strongest DNA-bending proteins (reviewed in references 22 and 23). In bacteria and their mobile genetic elements, IHF participates in a number of cellular processes such as DNA replication, site-specific recombination, bacteriophage packaging, and the positive and negative control of the expression of certain genes (reviewed in references 9, 10, and 23).Bacteriophages Mu, lambda cin-1, and 80 require IHF for plaque formation. The requirement of IHF for growth of Mu and lambda cin-1 appears to be satisfied by IHF's binding to a single identified site in each phage (14, 15). In both cases, IHF exerts its effect at the transcriptional level by modulating transcription from a promoter. For phage 80, a function (rha) which is inhibitory for growth of this phage in IHF Ϫ cells has been described; it maps in the QSR gene region of 80...

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Stabilization of bacteriophage Mu repressor‐operator complexes by the Escherichia coli integration host factor protein

Cited by 31 publications

References 37 publications

Regulation of bacteriophage Mu transposition

Regulation of bacteriophage Mu transposition

Involvement of Escherichia coli FIS protein in maintenance of bacteriophage mu lysogeny by the repressor: control of early transcription and inhibition of transposition

Phage HK022 Roi protein inhibits phage lytic growth in Escherichia coli integration host factor mutants

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