mutants of e. coli in which bacteriophage p4 cannot activate the late genes of its helper, bacteriophage p2. 1978369115
the plasmid status of satellite bacteriophage p4.p4 is a natural phasmid (phage-plasmid) that exploits different modes of propagation in its host escherichia coli. extracellularly, p4 is a virion, with a tailed icosahedral head, which encapsidates the 11.6-kb-long double-stranded dna genome. after infection of the e. coli host, p4 dna can integrate into the bacterial chromosome and be maintained in a repressed state (lysogeny). alternatively, p4 can replicate as a free dna molecule; this leads to either the lytic cycle or the plasmid state, de ...200111319927
bacteriophage p2 ogr and p4 delta genes act independently and are essential for p4 multiplication.satellite bacteriophage p4 requires the products of the late genes of a helper phage such as p2 for lytic growth. expression of the p2 late genes is positively regulated by the p2 ogr gene in a process requiring p2 dna replication. transactivation of p2 late gene expression by p4 requires the p4 delta gene product and works even in the absence of p2 dna replication. we have made null mutants of the p2 ogr and p4 delta genes. in the absence of the p4 delta gene product, p4 multiplication required ...19902193911
cloning and transposon vectors derived from satellite bacteriophage p4 for genetic manipulation of pseudomonas and other gram-negative bacteria.we developed transposon and cloning shuttle vectors for genetic manipulation of pseudomonas and other gram-negative bacteria, exploiting the unique properties and the broad host range of the satellite bacteriophage p4. p4::tn5 ap-1 and p4::tn5 ap-2 are suicide transposon vectors which have been used for efficient tn5 mutagenesis in pseudomonas putida. pkgb2 is a phasmid vector with a cloning capacity of about 7.5 kb; useful unique cloning sites are saci and sacii in the streptomycin resistance d ...19921329125
association of nonreplicating p2 dna to fast-sedimenting cell material following infection with satellite phage p4. 1976785805
a transactivation mutant of satellite phage p4. 1977329561
the yersinia high-pathogenicity island (hpi): evolutionary and functional aspects.the high-pathogenicity island (hpi) is a genomic island essential for the mouse-virulence phenotype in yersinia and indispensable for pathogenicity of yersinia and certain pathotypes of escherichia coli. in contrast to most genomic islands, the hpi is a functional island widely disseminated among members of the family of enterobacteriaceae. the hpi-encoded phage p4-like integrase together with excisionase and recombination sites make up the genetic mobility module of the island, while the sidero ...200415493818
rnase e and polyadenyl polymerase i are involved in maturation of ci rna, the p4 phage immunity factor.bacteriophage p4 immunity is controlled by a small stable rna (ci rna) that derives from the processing of primary transcripts. in previous works, we observed that the endonuclease rnase p is required for the maturation of ci rna 5'-end; moreover, we found that polynucleotide phosphorylase (pnpase), a 3' to 5' rna-degrading enzyme, is required for efficient 5'-end processing of ci rna, suggesting that 3'-end degradation of the primary transcript might be involved in the production of proper rnas ...200212051840
translation of two nested genes in bacteriophage p4 controls immunity-specific transcription phage p4, transcription of the left operon may occur from both the constitutive ple promoter and the regulated pll promoter, about 400 nucleotides upstream of ple. a strong rho-dependent termination site, timm, is located downstream of both promoters. when p4 immunity is expressed, transcription starting at ple is efficiently terminated at timm, whereas transcription from pll is immunity insensitive and reads through timm. we report the identification of two nested genes, kil and eta, located ...199910464191
a rho-dependent transcription termination site regulated by bacteriophage p4 rna immunity factor.the genes required for replication of the temperate bacteriophage p4, which are coded by the phage left operon, are expressed from a constitutive promoter (ple). in the lysogenic state, repression of the p4 replication genes is achieved by premature transcription termination. the leader region of the left operon encodes all the genetic determinants required for prophage immunity, namely: (i) the p4 immunity factor, a short, stable rna (ci rna) that is generated by processing of the leader transc ...19968806540
characterization of the capsid associating activity of bacteriophage p4's psu protein.the psu (polarity suppression) protein of satellite bacteriophage p4 was first characterized as an anti-terminator of transcription termination in escherichia coli. psu is also a structural component of mature p4 capsids, where it is present as a decoration protein. psu is located externally on the capsid surface, and it appears to protect the capsid from loss of dna through the capsid shell. the ability of psu to specifically bind to the p4 capsid appears not to be dependent on any p4 specific ...19938503180
the cox protein is a modulator of directionality in bacteriophage p2 site-specific recombination.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 addi ...19938253674
mechanisms of genome propagation and helper exploitation by satellite phage p4.temperate coliphage p2 and satellite phage p4 have icosahedral capsids and contractile tails with side tail fibers. because p4 requires all the capsid, tail, and lysis genes (late genes) of p2, the genomes of these phages are in constant communication during p4 development. the p4 genome (11,624 bp) and the p2 genome (33.8 kb) share homologous cos sites of 55 bp which are essential for generating 19-bp cohesive ends but are otherwise dissimilar. p4 turns on the expression of helper phage late ge ...19938246844
multiple regulatory mechanisms controlling phage-plasmid p4 propagation.bacteriophage p4 autonomous replication may result in the lytic cycle or in plasmid maintenance, depending, respectively, on the presence or absence of the helper phage p2 genome in the escherichia coli host cell. alternatively, p4 may lysogenize the bacterial host and be maintained in an immune-integrated condition. a key step in the choice between the lytic/plasmid vs. the lysogenic condition is the regulation of p4 alpha operon. this operon may be transcribed from two promoters, ple and pll, ...19957669338
propagation of satellite phage p4 as a plasmid.satellite phage p4 has two known options for propagation. in its lytic cycle, its regulatory functions can act in trans to alter the actions of a helper virus (p2), which then provides necessary gene products, including capsid proteins. p4 also can be propagated in the absence of a helper as a prophage, with distinct sites for integration within the escherichia coli chromosome. we determined that a single spontaneous mutation (vir1) of phage p4 allows a third mode of propagation: as a plasmid (a ...19827043461
conditionally replicating plasmid vectors that can integrate into the klebsiella pneumoniae chromosome via bacteriophage p4 site-specific recombination.p4 is a satellite phage of p2 and is dependent on phage p2 gene products for virion assembly and cell lysis. previously, we showed that a virulent mutant of phage p4 (p4 vir1) could be used as a multicopy, autonomously replicating plasmid vector in escherichia coli and klebsiella pneumoniae in the absence of the p2 helper. in addition to establishing lysogeny as a self-replicating plasmid, it has been shown that p4 can also lysogenize e. coli via site-specific integration into the host chromosom ...19836307977
cloning of the immunity repressor determinant of bacteriophage p2 in the pbr322 plasmid.through in vitro recombination of dna restriction fragments, we have constructed a plasmid, which expressed in vivo the immunity repressor gene (c) of bacteriophage p2. a bacterial strain carrying such a plasmid showed a high level of p2 specific immunity. it was lysogenized normally by an infecting p2, but the frequency of spontaneous phage production was reduced about 10(4) fold as compared to a normal p2 lysogen. satellite phage p4, known to derepress p2 lysogens, was unable to derepress the ...19806247614
cloning of the glutamine synthetase i gene from rhizobium meliloti.glutamine synthetase is a major enzyme in the assimilation of ammonia by members of the genus rhizobium. two forms of glutamine synthetase are found in members of the genus rhizobium, a heat-stable glutamine synthetase i (gsi) and a heat-labile gsii. as a step toward clarifying the role of these enzymes in symbiotic nitrogen fixation, we have cloned the structural gene for gsi from rhizobium meliloti 104a14. a gene bank of r. meliloti was constructed by using the bacteriophage p4 cosmid pmk318. ...19836137474
knotting of dna molecules isolated from deletion mutants of intact bacteriophage p4.dna molecules isolated from tailless phage particles (capsids) of bacteriophage p4 virl del10 are known to be knotted. we have found by electron microscopy that 80% of dna molecules isolated from intact phage particles of p4 virl del10 also contained knots. this observation indicates that the predominant form of p4 virl del10 dna within the intact phage particle is either knotted or in a configuration that permits knotting upon isolation. in comparison to p4 virl del10 (deleted 1000 basepairs), ...19853903657
regulation of the plasmid state of the genetic element p4.after infection of sensitive cells in the absence of a helper phage, the satellite bacteriophage p4 enters a temporary phase of uncommitted replication followed by commitment to either the repressed-integrated condition or the derepressed-high copy number mode of replication. the transient phase and the stable plasmid condition differ from each other in the pattern of protein synthesis, in the rate of p4 dna replication and in the expression of some gene functions. the regulatory condition chara ...19863528749
integration of satellite bacteriophage p4 in escherichia coli. dna sequences of the phage and host regions involved in site-specific recombination.we determined the dna sequences of regions essential for bacteriophage p4 integration. a 20 base-pair core sequence in both phage (p4attp) and host (p4attb) attachment regions contains the recombination site. in p4attp this sequence is flanked by five repeated sequences. a 1.3 x 10(3) base open reading frame codes for p4 integrase. two possible promoters are upstream from p4int. one would be recognized by escherichia coli rna polymerase and may be repressed by integrase protein. the second would ...19873119856
bacteriophage p4 dna replication. location of the p4 electron microscopic examination of replicating bacteriophage p4 dna molecules has revealed theta-type structures that replicate bidirectionally from a single origin. many replicating p4 dna molecules also contain long (2000 bases) single-strand dna regions at the growing fork that are deployed in a trans configuration, which supports the concept of continuous leading strand and discontinuous lagging strand syntheses. the position of the p4 origin was localized by the use of a plasmid complem ...19852989532
activation of prophage p4 by the p2 cox protein and the sites of action of the cox protein on the two phage genomes.phage p2 induces the unrelated prophage p4. in this paper we show that this is due to the activation of the p4 late promoter pii by the p2 cox protein. this is in contrast to the effects of cox on p2, for which it is known from previous work that it acts as a repressor of the promoter pc, which is responsible for expression of the immunity repressor c. the activator role of cox was revealed by its effect on replication of p4 dna and on the formation of chloramphenicol acetyltransferase when a pr ...19892657731
salmonella phage psp3, another member of the p2-like phage group.freshly isolated dna of phage psp3, whose morphology closely resembles that of phage p2, contained both circular and linear molecules about 31 kb in length. linear psp3 dna molecules possess single-stranded cohesive termini (cos). sequencing of the fragment anticipated to contain cos revealed a 19-base sequence identical to cos of phage 186. of the 107 bp to the right of cos, 94 were identical in 186 dna (88% similarity), and of the 370 bp to the left, 229 were identical (62% similarity). cos fl ...19911962462
the anti-immunity system of phage-plasmid n15: identification of the antirepressor gene and its control by a small processed rna.n15 is a temperate virus of escherichia coli related to lambdoid phages. however, unlike all other known phages, the n15 prophage is maintained as a low copy number linear dna molecule with covalently closed ends. the primary immunity system at the immb locus is structurally and functionally comparable to that of lambdoid phages, and encodes the immunity repressor cb. we have characterized a second locus, imma, in which clear plaque mutations were mapped, and found that it encodes an anti-immuni ...199910594823
association of a retroelement with a p4-like cryptic prophage (retronphage phi r73) integrated into the selenocystyl trna gene of escherichia coli.a new multicopy single-stranded dna (msdna-ec73) was found in a clinical strain of escherichia coli. retron-ec73, consisting of an msdna-coding region and the gene for reverse transcriptase (rt), was found to be a part of a 12.7-kb foreign dna fragment flanked by 29-bp direct repeats and integrated into the gene for selenocystyl-trna (selc) at 82 min on the e. coli chromosome. except for the 2.4-kb retron region, the integrated dna fragment showed remarkable homology to most of the bacteriophage ...19911712012
the gene fimu affects expression of salmonella typhimurium type 1 fimbriae and is related to the escherichia coli trna gene argu.the gene fimu, located on a recombinant plasmid carrying the salmonella typhimurium type 1 fimbrial gene cluster is closely related to the escherichia coli trna gene argu. the fimu gene complements an e. coli argu mutant that is a p2 lysogen, thereby allowing the phage p4 to grow in this strain but preventing the growth of phage lambda. in addition, fimu was shown to be involved in fimbrial expression since transformants of the e. coli argu mutant could produce fimbriae only in the presence of f ...19947914347
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