DNA sequences of bacteriophage P2 early genes cox and B and their regulatory sites

Haggård‐Ljungquist, Elisabeth; Kockum, K.; Le, Bertani

doi:10.1007/bf00330421

Cited by 24 publications

(21 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The product of gene C is the repressor that regulates the lysogenic state. The next expected gene would be cox, encoding a multifunctional protein of 91 amino acids (26). However, in phage ⌽AA91-ss, the cox gene is truncated by insertion of a long element, IS21, composed of two ORFs that encode a transposase and a transposition protein, respectively.…”

Section: Resultsmentioning

confidence: 99%

Evolution of a Self-Inducible Cytolethal Distending Toxin Type V-Encoding Bacteriophage from Escherichia coli O157:H7 to Shigella sonnei

Allué-Guardia

Imamovic

Muniesa

2013

J Virol

View full text Add to dashboard Cite

Some cdt genes are located within the genome of inducible or cryptic bacteriophages, but there is little information about the mechanisms of cdt transfer because of the reduced number of inducible Cdt phages described. In this study, a new self-inducible Myoviridae Cdt phage (⌽AA91) was isolated from a nonclinical O157:H7 Shiga toxin-producing Escherichia coli strain and was used to lysogenize a cdt-negative strain of Shigella sonnei. We found that the phage induced from S. sonnei (⌽AA91-ss) was not identical to the original phage. ⌽AA91-ss was used to infect a collection of 57 bacterial strains, was infectious in 59.6% of the strains, and was able to lysogenize 22.8% of them. The complete sequence of ⌽AA91-ss showed a 33,628-bp genome with characteristics of a P2-like phage with the cdt operon located near the cosR site. We found an IS21 element composed of two open reading frames inserted within the cox gene of the phage, causing gene truncation. Truncation of cox does not affect lytic induction but could contribute to phage recombination and generation of lysogens. The IS21 element was not present in the ⌽AA91 phage from E. coli, but it was incorporated into the phage genome after its transduction in Shigella. This study shows empirically the evolution of temperate bacteriophages carrying virulence genes after infecting a new host and the generation of a phage population with better lysogenic abilities that would ultimately lead to the emergence of new pathogenic strains.

show abstract

Section: Resultsmentioning

confidence: 99%

Evolution of a Self-Inducible Cytolethal Distending Toxin Type V-Encoding Bacteriophage from Escherichia coli O157:H7 to Shigella sonnei

Allué-Guardia

Imamovic

Muniesa

2013

J Virol

View full text Add to dashboard Cite

show abstract

“…The cox gene is the first gene of the P2 early operon, and it encodes a 91-amino-acid-long, slightly basic polypeptide of 10.3 kDa (12). P2 Cox is a multifunctional protein with at least three distinct functions: (i) P2 prophage excisionase, (ii) transcriptional repressor of P2 Pc promoter, and (iii) transcriptional activator of the unrelated phage P4 P LL promoter.…”

mentioning

confidence: 99%

The Multifunctional Bacteriophage P2 Cox Protein Requires Oligomerization for Biological Activity

Eriksson

Haggård‐Ljungquist

2000

J Bacteriol

Self Cite

View full text Add to dashboard Cite

The Cox protein of bacteriophage P2 is a multifunctional protein of 91 amino acids. It is directly involved in the site-specific recombination event leading to excision of P2 DNA out of the host chromosome. In this context, it functions as an architectural protein in the formation of the excisome. Cox is also a transcriptional repressor of the P2 Pc promoter, thereby ensuring lytic growth. Finally it promotes derepression of prophage P4, a nonrelated defective satellite phage, by activating the P4 P LL promoter that controls P4 DNA replication. In this case it binds upstream of the P LL promoter, which normally is activated by the P4 Delta protein. In this work we have analyzed the native form of the Cox protein in vivo, using a bacteriophage cI-based oligomerization assay system, and in vitro, using gel filtration, cross-linking agents, and gel retardation assays. We found that P2 Cox has a strong oligomerization function in vivo as well as in vitro. The in vitro analysis indicates that its native form is a tetramer that can self-associate to octamers. Furthermore we show that oligomerization is necessary for the biological activity by characterizing different cox mutants and that oligomerization is mediated by the C-terminal region.Bacteriophage P2 belongs to a group of serologically related, nonlambdoid phages that can infect several enteric bacterial species (4). It is a temperate DNA phage; i.e., after infection it can either grow lytically, leading to cell lysis and release of progeny phage particles, or form lysogeny. In the latter case, the infected cell survives, and the P2 DNA becomes integrated into the host chromosome through a site-specific recombination event. P2 cox (control of excision) mutants were originally isolated as P2 phages that were unable to liberate phages spontaneously during growth of a lysogenic strain (16). In addition, the cox mutants showed an increased frequency of lysogenization and integrase-mediated site-specific recombination between infecting phages (2, 16).The cox gene is the first gene of the P2 early operon, and it encodes a 91-amino-acid-long, slightly basic polypeptide of 10.3 kDa (12). P2 Cox is a multifunctional protein with at least three distinct functions: (i) P2 prophage excisionase, (ii) transcriptional repressor of P2 Pc promoter, and (iii) transcriptional activator of the unrelated phage P4 P LL promoter.In the site-specific recombination event, P2 Cox protein is directly involved as an architectural protein, where it has been shown to be required for excisive recombination and inhibitory for integrative recombination (32,33). In this case Cox is analogous to Xis. As a transcriptional repressor it represses the P2 Pc promoter that controls the expression of the P2 integrase and the immunity repressor C, thereby ensuring lytic growth (21). At high concentrations it autoregulates its own expression, since it reduces the activity of the early promoter Pe (21). Thus, the P2 Cox protein has in this case a function analogous to that of the well-studied Cro protein.T...

show abstract

“…cox is the first gene of the P2 early operon, and the transcript is initiated by the early promoter PC, which is controlled by the immunity repressor C (7). The repressor promoter, Pc, which initiates the C-int operon, has opposite polarity to Pc, and the two transcripts overlap by about 30 nucleotides.…”

mentioning

confidence: 99%

The Cox protein is a modulator of directionality in bacteriophage P2 site-specific recombination

Haggård‐Ljungquist

1993

J Bacteriol

View full text Add to dashboard Cite

The P2 Cox protein is known to repress the Pc promoter, which controls the expression of the P2 immunity repressor C. It has also been shown that Cox can activate the late promoter PLL of the unrelated phage P4. By this process, a P2 phage infecting a P4 lysogen is capable of inducing replication of the P4 genome, an example of viral transactivation. In this report, we present evidence that Cox is also directly involved in both prophage excision and phage integration. While purified Cox, in addition to P2 Int and Escherichia coli integration host factor, was required for attR X attL (excisive) recombination in vitro, it was inhibitory to attP X attB (integrative) recombination. The same amounts of Int and integration host factor which mediated optimal excisive recombination in vitro also mediated optimal integrative recombination. We quantified and compared the relative efficiencies of attB, attR, and attL in recombination with attP and discuss the functional implications of the results. DNase I protection experiments revealed an extended 70-bp Cox-protected region on the right arm of attP, centered at about +60 bp from the center of the core sequence. Gel shift assays suggest that there are two Cox binding sites within this region. Together, these data support the theory that in vivo, P2 can exert control over the direction of recombination by either expressing Int alone or Int and Cox together.The P2 cox (control of excision) function was originally described by the isolation of cox mutants which had the following phenotypes: (i) the lysogens were unable to release phage spontaneously (10); (ii) int-mediated recombination between two phages was increased 20-fold when the parental phages carried a cox mutation (10); and (iii) their frequency of lysogenization was increased 3-to 5-fold over that of wild-type P2 (3). These early findings indicated that the cox gene product stimulates prophage excision and inhibits lysogenization and site-specific recombination between two infecting phages.cox is the first gene of the P2 early operon, and the transcript is initiated by the early promoter PC, which is controlled by the immunity repressor C (7).

show abstract

DNA sequences of bacteriophage P2 early genes cox and B and their regulatory sites

Cited by 24 publications

References 20 publications

Evolution of a Self-Inducible Cytolethal Distending Toxin Type V-Encoding Bacteriophage from Escherichia coli O157:H7 to Shigella sonnei

Evolution of a Self-Inducible Cytolethal Distending Toxin Type V-Encoding Bacteriophage from Escherichia coli O157:H7 to Shigella sonnei

The Multifunctional Bacteriophage P2 Cox Protein Requires Oligomerization for Biological Activity

The Cox protein is a modulator of directionality in bacteriophage P2 site-specific recombination

Contact Info

Product

Resources

About