| determination of capsid size by satellite bacteriophage p4. | satellite bacteriophage p4 requires all morphogenic gene products provided by a helper phage, such as coliphage p2, to assemble its own capsid, which is one-third the volume of the larger helper capsid. we have isolated a satellite phage p4 sid (size determination) mutant that is unable to direct the assembly of the small wild-type-size p4 capsid. instead, this mutant produces p4 plaque-forming units with large p2-size capsids which contain two or three copies of the p4 sid1 genome. p4 sid1 is e ... | 1978 | 272656 |
| construction of a novel plasmid-phage hybrid: use of the hybrid to demonstrate cole1 dna replication in vivo in the absence of a cole1-specified protein. | a hybrid bacteriophage, p420, was constructed in vitro; it contains part of bacteriophage p4 and a 3.6-kilobase derivative of plasmid cole1. in escherichia coli, the plasmid-phage hybrid can exist as a stable plasmid or can be packaged into infective bacteriophage particles. replication of p420, directed by the cole1 replicon, was found to occur after p420 phage infection of e. coli cells that had been incubated in the presence of chloramphenicol. replication began without a lag period and resul ... | 1978 | 276860 |
| a transactivation mutant of satellite phage p4. | | 1977 | 329561 |
| mutants of e. coli in which bacteriophage p4 cannot activate the late genes of its helper, bacteriophage p2. | | 1978 | 369115 |
| size distribution of dna replicative intermediates in bacteriophage p4 and in escherichia coli. | | 1979 | 374741 |
| physical mapping of the satellite phage p4 genome. | | 1978 | 664207 |
| restriction endonuclease cleavage map of bacteriophage p4 dna. | | 1978 | 664209 |
| control of gene activation of p2 prophage by satellite phage p4. | | 1978 | 664256 |
| mutations of bacteriophage p2 which prevent activation of p2 late genes by satellite phage p4. | | 1978 | 741656 |
| viral interference at the level of capsid size determination by satellite phage p4. | | 1978 | 745236 |
| association of nonreplicating p2 dna to fast-sedimenting cell material following infection with satellite phage p4. | | 1976 | 785805 |
| relief of p2 bacteriophage amber mutant polarity by the satellite bacteriophage p4. | | 1976 | 789895 |
| ecori endonuclease cleavage map of bacteriophage p4-dna. | | 1975 | 1098276 |
| the helper dependence of satellite bacteriophage p4: which gene functions of bacteriophage p2 are needed by p4? | | 1975 | 1099784 |
| escherichia coli deoxyribonucleic acid synthesis mutants: their effect upon bacteriophage p2 and satellite bacteriophage p4 deoxyribonucleic acid synthesis. | escherichia coli c strains containing different deoxyribonucleic acid (dna) synthesis mutations have been tested for their support of the dna synthesis of bacteriophage p2 and its satellite phage p4. bacteriophage p2 requires functional dnab, dnae, and dnag e. coli gene products for dna synthesis, whereas it does not require the products of the dnaa, dnac, or dnah genes. in contrast, the satellite virus p4 requires functional dnae and dnah gene products for dna synthesis and does not need the pr ... | 1975 | 1100599 |
| 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 ... | 1992 | 1329125 |
| bacteriophage p4 immunity controlled by small rnas via transcription termination. | satellite bacteriophage p4 immunity is encoded within a short dna region 357 bp long containing the promoter ple and 275 bp downstream. ple is active both in the early post-infection phase, when genes necessary for p4 lytic cycle are transcribed from this promoter, and in the lysogenic condition, when expression of the above genes is prevented by prophage immunity. in order to understand how p4 immunity is elicited, we have characterized the transcription pattern during the establishment and the ... | 1992 | 1484493 |
| image reconstruction from cryo-electron micrographs reveals the morphopoietic mechanism in the p2-p4 bacteriophage system. | the satellite bacteriophage p4 does not have genes coding for any major structural proteins, but assembles a capsid from the gene products of bacteriophage p2. the capsid assembled under control of p4 is smaller (45 nm) than the normal p2 capsid (60 nm). the low resolution (4.5 nm) structures of p2 and p4 capsids were determined by cryo-electron microscopy and image processing. the capsid of p2 shows t = 7 symmetry with most of the mass clustered as 12 pentamers and 60 hexamers. the p4 capsid ha ... | 1992 | 1547786 |
| organization and evolution of bacterial and bacteriophage primase-helicase systems. | amino acid sequences of primases and associated helicases involved in the dna replication of eubacteria and bacteriophages t7, t3, t4, p4, and p22 were compared by computer-assisted methods. there are two types of such systems, the first one represented by distinct helicase and primase proteins (e.g., dnab and dnag proteins of escherichia coli), and the second one by single polypeptides comprising both activities (gp4 of bacteriophages t7 and t3, and alpha protein of bacteriophage p4). pronounce ... | 1992 | 1569588 |
| the polarity suppression factor of bacteriophage p4 is also a decoration protein of the p4 capsid. | we show that the product of the polarity suppression (psu) gene from bacteriophage p4 associates with p4 capsids. this association can occur when psu is (i) provided in vivo from the p4 genome or from a plasmid or (ii) provided in vitro by mixing viable phage particles with psu protein. psu is unable to associate with the larger capsid of p4's helper phage p2. discrimination of the p4 and p2 capsids by psu appears to be independent of the presence of the p4 genome in the capsid, since p2 size ca ... | 1992 | 1585650 |
| a common sequence motif, -e-g-y-a-t-a-, identified within the primase domains of plasmid-encoded i- and p-type dna primases and the alpha protein of the escherichia coli satellite phage p4. | dna primases encoded by the conjugative plasmids colib-p9 (inci1), rp4, and r751 (incp), and the protein of the escherichia coli satellite phage p4 alpha were shown to contain a common amino acid sequence motif -e-g-y-a-t-a-. the p4 alpha gene product, required for initiation of phage dna replication, exhibits primase activity on single-stranded circular dna templates. this priming activity resembles the enzymatic activity of dna primases encoded by conjugative plasmids in terms of template util ... | 1992 | 1618804 |
| 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 ... | 1991 | 1712012 |
| morphopoietic switch mutations of bacteriophage p2. | during the growth of bacteriophage p4, for which the genome of bacteriophage p2 is needed as helper, the decision whether to make large, p2 size, heads or small, p4 size, heads depends on the size-directing function of p4's sid gene and on p2's "sid responsiveness." p2 mutants (=p2 sir) impaired in their response to p4's sid function are readily obtainable as one class of p2 plaque formers selected on certain p4 cl plasmid lysogens. we describe nine p2 sir mutants of independent origin. for eigh ... | 1991 | 1840708 |
| genetic analysis of the dna recognition sequence of the p2 cox protein. | the cox protein of temperate escherichia coli phage p2 is involved in three important biological processes: (i) excision of the integrated prophage genome (g. lindahl and m. sunshine, virology 49:180-187, 1972), (ii) transcriptional repression of the p2 pc promoter, which controls the expression of the immunity repressor c and the integrase (s. saha, e. haggård-ljungquist, and k. nordström, embo j. 6:3191-3199, 1987), and (iii) transcriptional activation of the late pii promoter of the unrelated ... | 1991 | 1870195 |
| the psu protein of bacteriophage p4 is an antitermination factor for rho-dependent transcription termination. | a 0.7-kbp dna fragment from bacteriophage p4 that contained the polarity suppression (psu) gene was cloned in an expression plasmid. induction of the plasmid-borne psu gene resulted in the overproduction of a protein having the biological properties of the p4-induced polarity suppressor. in vivo, psu protein acted in trans to suppress rho-dependent polarity in the late genes of an infecting p2 phage, in plasmid operons, and in the host chromosome. psu action did not require the presence of other ... | 1991 | 1938879 |
| 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 ... | 1991 | 1962462 |
| mutational analysis of a bacteriophage p4 late promoter. | transcription from the late psid promoter of satellite bacteriophage p4 is dependent on the bacterial rna polymerase carrying the sigma 70 subunit and is positively regulated by the product of the p4 delta gene or the ogr gene of helper bacteriophage p2. through deletion and mutational analyses of the psid promoter, we identified mutations in the -10 region and in a region of hyphenated dyad symmetry centered around position -55 that inactivate psid. most of these mutations alter base pairs that ... | 1991 | 1987128 |
| interactions between satellite bacteriophage p4 and its helpers. | the helper dependence of satellite phage p4 superimposes an additional set of regulatory interactions on those required for the independent maintenance of p4 or its helpers. these interactions allow p4 to exploit a helper phage under a variety of circumstances and can affect expression of the immunity functions and late genes of both phages. the phage p2 lysis/lysogeny decision involves two competing repressors regulating mutually exclusive promoters in the early control region. in the absence o ... | 1990 | 2088176 |
| deletion analysis of a bacteriophage p2 late promoter. | we have fused the promoter (pf) for the p2 late fetud operon to the gene (cat) encoding chloramphenicol acetyltransferase (cat) in a plasmid vector. synthesis of cat in escherichia coli strains carrying this plasmid requires the product of the p2 ogr gene or the satellite phage p4 transactivation gene, delta. our results demonstrate that these phage-encoded transcriptional regulatory proteins are necessary and sufficient for activation of p2 late transcription in this reporter plasmid. positive ... | 1990 | 2129530 |
| quantitative adaptation of the bacteriophage p4 dna unknotting assay for use in the biochemical and pharmacological characterization of topoisomerase ii. | the atp-dependent unknotting of phage p4 dna is a highly specific assay for type ii topoisomerases. despite the unique specificity of the assay, however, its semiquantitative design has limited its use in studying the biochemical properties of these enzymes. to overcome this problem, we have modified the p4 dna unknotting assay to provide a sensitive and reproducible method for quantifying topoisomerase ii activity. methods are described for accurate measurement of 10-100 ng of unknotted p4 dna. ... | 1990 | 2169250 |
| dna sequence of satellite bacteriophage p4. | | 1990 | 2183201 |
| purification and properties of the bacteriophage p2 ogr gene product. a prokaryotic zinc-binding transcriptional activator. | the bacteriophage p2 ogr gene product, a 72-residue basic protein rich in cysteine and histidine, is a positive regulatory factor for phage late gene transcription in both p2 and satellite phage p4. we have developed a simple purification procedure for ogr protein synthesized from an overproducing plasmid. inclusion bodies formed upon overproduction were denatured using 8 m urea, and the overproduced protein was purified by gel filtration. the purified ogr was allowed to refold under optimized c ... | 1990 | 2185249 |
| a mutation of the transactivation gene of satellite bacteriophage p4 that suppresses the rpoa109 mutation of escherichia coli. | satellite bacteriophage p4 requires the products of the late genes of a helper such as p2 in order to grow lytically. the escherichia coli rpoa109 mutation, which alters the alpha subunit of rna polymerase, prevents transcription of the late genes of bacteriophage p2. suppressor mutations that define the p2 ogr gene overcome this block. we found that p4 lytic growth using a p2 ogr+ prophage helper was prevented by the rpoa109 mutation but that this block was overcome when the p2 helper carried t ... | 1990 | 2193910 |
| 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 ... | 1990 | 2193911 |
| nonessential region of bacteriophage p4: dna sequence, transcription, gene products, and functions. | we sequenced the leftmost 2,640 base pairs of bacteriophage p4 dna, thus completing the sequence of the 11,627-base-pair p4 genome. the newly sequenced region encodes three nonessential genes, which are called gop, beta, and cii (in order, from left to right). the gop gene product kills escherichia coli when the beta protein is absent; the gop and beta genes are transcribed rightward from the same promoter. the cii gene is transcribed leftward to a rho-independent terminator. mutation of this te ... | 1990 | 2403440 |
| reduced formation of lesions in the dna of a multidrug-resistant l1210 subline selected for teniposide resistance. | earlier studies have suggested that higher cellular levels of teniposide (vm-26) are required for the inhibition of growth in l1210/vm-26 sublines than in parental l1210 cells. on the basis of this observation, we hypothesized that resistance to vm-26, which is partly attributed to multidrug resistance, also resulted in reduced formation of dna lesions by the drug. in confirmation of this hypothesis, equitoxic concentrations of vm-26 produced fewer breaks in the dna of lia5 microm cells, the pro ... | 1989 | 2538249 |
| 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 ... | 1989 | 2657731 |
| mechanism of resistance of non-cycling mammalian cells to 4'-[9-acridinylamino]methanesulphon-m-anisidide: role of dna topoisomerase ii in log- and plateau-phase cho cells. | cho-aa8 cells were used as a model system to study the role of dna topoisomerase ii in the resistance of non-cycling cells to amsacrine. plateau-phase aa8 cells have previously been shown to be resistant to amsacrine and to contain fewer dna breaks than log-phase cells after drug treatment (robbie, m.a., baguley, b.c., denny, w.a., gavin, j.r. and wilson, w.r. (1988) cancer res., in press). the phage p4-unknotting activity of nuclear extracts decreased 2-fold when aa8 cells entered into the non- ... | 1988 | 2831986 |
| cell line selectivity and dna breakage properties of the antitumour agent n-[2-(dimethylamino)ethyl]acridine-4-carboxamide: role of dna topoisomerase ii. | n-[2-(dimethylamino)ethyl]acridine-4-carboxamide (nsc 601316) is a dna intercalating experimental antitumour agent which is curative against the lewis lung carcinoma in mice. its action has been compared with amsacrine, its inactive isomer oamsa, the solid tumour active derivative ci-921 (nsc 343499), a c-6 methylene chain-linked bisacridine (nsc 210733), 9-aminoacridine and quinacrine. all compounds inhibited the unknotting of phage p4 dna by topoisomerase ii in nuclear extracts prepared from l ... | 1988 | 2850193 |
| bacteriophage p4 dna replication. location of the p4 origin. | an 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 ... | 1985 | 2989532 |
| inhibition of calf thymus type ii dna topoisomerase by poly(adp-ribosylation). | the effect of poly(adp-ribosylation) on calf thymus topoisomerase type ii reactions has been investigated. unknotting of phage p4 head dna, and relaxation and catenation of supercoiled pm2 dna are inhibited. we conclude that the inhibition results from poly(adp-ribosylation) on the following grounds. firstly, the enzyme poly(adp-ribose) (padpr) synthetase and nad are required, secondly, the competitive synthetase inhibitor nicotinamide abolishes topoisomerase inhibition, and thirdly, the polymer ... | 1985 | 2998783 |
| 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 ... | 1987 | 3119856 |
| organization and expression of the satellite bacteriophage p4 late gene cluster. | the satellite bacteriophage p4 genes for capsid size determination (sid), transactivation (delta), and polarity suppression (psu) are cotranscribed at late times after infection from a single p4 late promoter (psid) that lies to the left of the sid gene. while the -10 region of this promoter is similar to the consensus sequence for escherichia coli rna polymerase, the -35 region shares no homology with known classes of e. coli promoters. the -10 and -35 regions of psid share no homology with the ... | 1986 | 3295254 |
| bacteriophage p4 dna replication. nucleotide sequence of the p4 replication gene and the cis replication region. | a 3100 base piece of dna from the 11,500 base genome of bacteriophage p4 was analyzed for its nucleotide sequence. this segment of dna contains two open reading frames of 106 and 777 amino acid residues; the latter of which is the coding sequence for the mr 84,841 alpha protein, which is necessary for p4 dna replication and is thought to act as a p4-specific dna primase. a region of about 300 base-pairs localized just beyond the alpha gene and about 4500 bases from the origin of replication (ori ... | 1987 | 3309336 |
| in vitro transcription from the late promoter of bacteriophage p4. | the late genes of satellite bacteriophage p4 are cotranscribed from a single promoter which shares little homology with known classes of escherichia coli promoters (e. dale, g. christie, and r. calendar, j. mol. biol. 192:793-803, 1986). in a coupled transcription-translation system, the p4 late gene promoter was activated by either the delta protein of p4 or the ogr protein of helper phage p2 in the absence of any other phage-encoded factor. delta-dependent transcription was inhibited by antibo ... | 1988 | 3403508 |
| 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 ... | 1986 | 3528749 |
| the replication of bacteriophage p4 dna in vitro. partial purification of the p4 alpha gene product. | a soluble enzyme system has been prepared from a phage p4-infected escherichia coli strain that supports the replication of exogenous, supercoiled p4 dna. this dna synthesis in vitro depends upon the four deoxyribonucleotides and atp, but is enhanced about four- to fivefold by the presence of other ribonucleotides. e. coli dna polymerase iii holoenzyme, the e. coli single-strand dna binding protein, and the partially purified p4 alpha gene product are required for replication in vitro. rifamycin ... | 1985 | 3874288 |
| 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), ... | 1985 | 3903657 |
| analysis of spontaneous deletion mutants of satellite bacteriophage p4. | spontaneous deletion mutants of satellite bacteriophage p4 have been isolated and characterized. all of the deletions analyzed that were between 850 and 1,700 base pairs long are within the region nonessential for p4 lytic development; some of them cover the cii or the gop locus. | 1985 | 3973980 |
| bacteriophage p2 late promoters. ii. comparison of the four late promoter sequences. | the late genes of bacteriophage p2 are clustered into four transcription units. we have reported the transcription initiation sites for two of the late messenger rnas, encoding genes qp and onmlkrs. we have now located the 5' ends of the two remaining late mrnas. the first gene in the vjhg transcription unit has been located by dna sequence determination of the single nucleotide change in a v amber mutant. location of the first gene in the fetud transcription unit has been inferred from the dna ... | 1985 | 3981640 |
| helper-dependent bacteriophage p4: a model satellite virus and its implications for animal virology. | | 1973 | 4348876 |
| head size determination and the morphogenesis of satellite phage p4. | | 1974 | 4448101 |
| in vitro packaging of satellite phage p4 dna. | satellite phage p4 directs the capsid proteins of its helper phage, p2, to form a head which is only one-third the size of the normal p2 head. the p2 head contains a genome of molecular weight 22 x 10(6), while the small p4 head contains a genome with a molecular weight of only 7 x 10(6). we have used in vitro dna packaging to test whether p2 and p4 phage head sizes are determined by dna size. the small dna of satellite phage p4 added to a p2-infected cell extract was packaged primarily into par ... | 1974 | 4526304 |
| a transcribing activity induced by satellite phage p4. | satellite bacteriophage p4 induces a new transcribing enzyme that synthesizes polyriboguanylic acid in the presence of the poly(dg).poly(dc) homopolymer pair. this transcribing activity was partially purified and shown to be distinct from the host rna polymerase. analysis of conditional lethal mutants suggests that this new enzyme is necessary for replication of phage dna. | 1972 | 4562749 |
| bacteriophage p4: a satellite virus depending on a helper such as prophage p2. | | 1973 | 4571379 |
| satellite bacteriophage p4: characterization of mutants in two essential genes. | | 1973 | 4574874 |
| replication of bacteriophage p4 dna in a nonlysogenic host. | | 1971 | 5543274 |
| multiplication of bacteriophage p4 in the absence of replication of the dna of its helper. | | 1971 | 5543291 |
| cloning of the integration and attachment regions of bacteriophage p4. | the integration and attachment regions of bacteriophage p4 have been cloned into a multicopy plasmid. this plasmid can integrate into the e. coli chromosome at the same location as the parent phage. integration increases the stability of the plasmid and allows it to be retained even under conditions in which a non-integrated plasmid would be lost. none of the genes needed for p4 lytic growth is required for integration. the p4 integration and attachment regions have been cloned on separate plasm ... | 1984 | 6092863 |
| nucleotide sequence of the essential region of bacteriophage p4. | nucleotide sequence of one-third of the genome of coliphage p4 has been obtained and mutations virl, epsilon am104, ci405, sidl, and delta 35 identified. the epsilon gene likely encodes a 10 kd protein with epsilon am104 being located at the beginning of the gene. ci405, a proposed repressor gene mutation, is located in a sequence capable of coding for a 15 kd protein. a new class of p4 mutations, ash, is located in the neighborhood of ci405. two tata-like sequences are mapped 5' to this ci (ash ... | 1984 | 6095206 |
| 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. ... | 1983 | 6137474 |
| 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 ... | 1980 | 6247614 |
| recombinant p4 bacteriophages propagate as viable lytic phages or as autonomous plasmids in klebsiella pneumoniae. | we demonstrate the use of bacteriophage p4 as a molecular cloning vector in klebsiella pneumoniae. a hybrid p4 phage, constructed in vitro, that contains a k. pneumoniae hisdg dna fragment can be propagated either as a lytic viable specialized transducing phage or as an autonomous, self-replicating plasmid. hybrid p4 genomes existing as plasmids can be readily converted into non-defective p4-hybrid phage particles by superinfection with helper phage p2. infection of a k. pneumoniae hisd non-p2 l ... | 1980 | 6255293 |
| recombination between satellite phage p4 and its helper p2. i. in vivo and in vitro construction of p4: :p2 hybrid satellite phage. | | 1981 | 6271624 |
| recombination between satellite phage p4 and its helper p2. ii. in vitro construction of a helper-independent p4: :p2 hybrid phage. | | 1981 | 6271625 |
| novel topologically knotted dna from bacteriophage p4 capsids: studies with dna topoisomerases. | dna molecules isolated from bacteriophage p4 are mostly linear with cohesive ends capable of forming circular and concatemeric structures. in contrast, almost all dna molecules isolated form p4 tailless capsids (heads) are monomeric dna circles with their cohesive ends hydrogen-bonded. different form simple dna circles, such p4 head dna circles contain topological knots. gel electrophoretic and electronmicroscopic analyses of p4 head dna indicate that the topological knots are highly complex and ... | 1981 | 6272191 |
| interaction of satellite phage p4 with phage 186 helper. | | 1982 | 6278725 |
| 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 ... | 1983 | 6307977 |
| bacteriophage p2 late promoters. transcription initiation sites for two late mrnas. | divergent transcription of two of the bacteriophage p2 late mrnas, encoding genes qp and onmlkrs, is initiated from opposite strands of the dna in a region near the left end of the p2 genome. the first gene in each of these transcription units (p and o) has been located in the nucleotide sequence by amino-terminal sequence analysis of the p gene product and by dna sequence determination of the single nucleotide changes in two o amber mutants. the 5' ends of the p and o gene mrnas are separated b ... | 1983 | 6308267 |
| an escherichia coli gene required for bacteriophage p2-lambda interference. | the gene old of bacteriophage p2 is known to (i) cause interference with phage lambda growth; (ii) kill recb- mutants of escherichia coli after p2 infection; and (iii) determine increased sensitivity of p2 lysogenic cells to x-ray irradiation. in all of these phenomena, inhibition of protein synthesis occurs. we have isolated bacterial mutants, named pin (p2 interference), able to suppress all of the above-mentioned phenomena caused by the old+ gene product and the concurrent protein synthesis i ... | 1983 | 6355505 |
| plasmid mode of propagation of the genetic element p4. | the satellite bacteriophage p4, in the presence of a helper phage, can enter either the lytic or the lysogenic cycle. in the absence of the helper, p4 can integrate in the bacterial chromosome. in addition, the partially immunity-insensitive mutant p4 vir1 can be maintained as a plasmid. we have found that in the absence of the helper, p4 wt also can be maintained as a plasmid, and that both p4 wt and p4 vir1 have two options for their intracellular propagation: a repressed-integrated or a derep ... | 1984 | 6492154 |
| circular genetic map of satellite bacteriophage p4. | a genetic map of satellite bacteriophage p4 has been constructed by means of standard multifactor crosses. the genetic map appears to be a circular permutation of the mature dna physical map. in addition, a set of markers appear to be linked both to the left and to the right of the same gene alpha. these facts suggest that the p4 genetic map is circular. since terminal redundancy and/or cyclic permutation are not known to be present in p4 mature dna, the circularity of p4 genetic map may reflect ... | 1983 | 6573817 |
| in vitro activation of bacteriophage p2 late gene expression by extracts from phage p4-infected cells. | we have used a cell-free, dna-dependent protein-synthesizing system to study the stimulation of phage p2 late gene expression by satellite phage p4. an activity is present in extracts prepared from p4-infected cells, which, when added to the in vitro system with p2 dna template, stimulates the synthesis of a number of p2 proteins. these stimulated proteins include the major p2 capsid protein (n gene product) and a major component of the p2 phage tail (fii gene product). extracts prepared from p4 ... | 1983 | 6620459 |
| the bacteriophage p4 alpha gene is the structural gene for bacteriophage p4-induced rna polymerase. | two temperature-sensitive mutants of satellite phage p4 which do not synthesize p4 dna at the nonpermissive temperature have been isolated. one of these phage is mutated in the p4 alpha gene. it complements a p4 delta mutant, but not a p4 alpha amber mutant; both mutants are phenotypically identical to alpha amber mutants in all properties studied. they synthesize p4 early proteins 1 and 2 as well as two additional p4-induced early proteins, 5 and 6, which are described here. p4 late proteins ar ... | 1983 | 6887349 |
| genetic analysis of bacteriophage p4 using p4-plasmid cole1 hybrids. | a set of plasmids that contain fragments of the bacteriophage p4 genome has been constructed by deleting portions of a p4-cole1 hybrid. a p4 genetic map has been established and related to the physical map by examining the ability of these plasmids to rescue various p4 mutations. the p4 virl mutation and p4 genes involved in dna replication (alpha), activation of p2 helper genes (delta and epsilon), polarity suppression (psu) and head size determination (sid) have been mapped, as has the region ... | 1980 | 6929401 |
| mutants of satellite bacteriophage p4 that are defective in the suppression of transcriptional polarity. | | 1981 | 7021852 |
| lysogenization by satellite phage p4. | | 1981 | 7023020 |
| 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 ... | 1982 | 7043461 |
| capsid structure of satellite phage p4 and its p2 helper. | | 1982 | 7077742 |
| bacteriophage p2: genes involved in baseplate assembly. | the sequences of two previously defined tail genes, v and j, of the temperate bacteriophage p2, and those of two new essential tail genes, w and i, were determined. their order is the late gene promoter, vwji, followed by the tail fiber genes h and g, and a transcription terminator. the v gene product is the small spike at the tip of the tail, and the j gene product lies at the edge of the baseplate. the w gene product may be homologous to the product of gene 25 of t4 phage, which is part of the ... | 1995 | 7483254 |
| division inhibition gene dicf of escherichia coli reveals a widespread group of prophage sequences in bacterial genomes. | the genomes of various eubacteria were analyzed by southern blot hybridization to detect sequences related to the segment of the defective lambdoid prophage kim which encodes dicf rna, an antisense inhibitor of cell division gene ftsz in escherichia coli k-12. among the homologous sequences found, one fragment from e. coli b, similar to a piece of rac prophage, and two fragments from shigella flexneri were cloned and sequenced. dicf-like elements similar to transcriptional terminators were found ... | 1994 | 7508908 |
| excision of a p4-like cryptic prophage leads to alp protease expression in escherichia coli. | the escherichia coli k-12 alpa gene product, when overproduced from a multicopy plasmid, leads to suppression of the capsule overproduction and uv sensitivity phenotypes of cells mutant for the lon atp-dependent protease. this suppression has previously been shown to correlate with increased in vivo activity of a previously unknown energy-dependent proteolytic activity capable of degrading lon substrates, the alp protease. we show in an accompanying paper that alpa, which has homology to a short ... | 1994 | 7511583 |
| purification and characterization of the bacteriophage p4 delta protein. | the bacteriophage p4 delta protein is a transcriptional activator of the late genes of p4 as well as the late genes of its helpers, such as bacteriophage p2. delta was purified, using a variation of the male fusion system. with this method we purified two forms of delta: a fusion of male and delta and a unfused form. the fusion by itself is not active in vivo or in vitro, but the mixture of the fusion and the unfused delta is active in both. using nitrocellulose filtration and gel mobility shift ... | 1995 | 7601839 |
| analysis of the escherichia coli genome vi: dna sequence of the region from 92.8 through 100 minutes. | the 338.5 kb of the escherichia coli genome described here together with previously described segments bring the total of contiguous finished sequence of this genome to > 1 mb. of 319 open reading frames (orfs) found in this 338.5 kb segment, 147 (46%) are potential new genes. the positions of several genes which had been previously located here by mapping or partial sequencing have been confirmed. several orfs have functions suggested by similarities to other characterised genes but cannot be a ... | 1995 | 7610040 |
| domain structure of phage p4 alpha protein deduced by mutational analysis. | bacteriophage p4 dna replication depends on the product of the alpha gene, which has origin recognition ability, dna helicase activity, and dna primase activity. one temperature-sensitive and four amber mutations that eliminate dna replication in vivo were sequenced and located in the alpha gene. sequence analysis of the entire gene predicted a domain structure for the alpha polypeptide chain (777 amino acid residues, m(r) 84,900), with the n terminus providing the catalytic activity for the pri ... | 1995 | 7635818 |
| the capsid size-determining protein sid forms an external scaffold on phage p4 procapsids. | although the phages p2 and p4 build their capsids from the same precursor, the product of the p2 n gene, the two capsids differ in size: p2 builds a 60 nm, t = 7 capsid from 420 subunits, whereas p4 makes a 45 nm, t = 4 capsid from 240 subunits. this difference leads to substantial changes in shell geometry and subunit interactions. previous results have demonstrated that the p4 sid gene is responsible for the assembly of p4-sized shells. we have used cryo-electron microscopy and image reconstru ... | 1995 | 7643390 |
| 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, ... | 1995 | 7669338 |
| peptide presentation by bacteriophage p4. | this article focuses on bacteriophage p4 as a potential peptide display phage by exploring the possibility of using the p4 capsid decoration component, psu, as a peptide carrier protein. psu is non-essential for p4 growth but it enhances the stability of the p4 capsid by binding to its exterior. we have constructed a unique saci cloning site in the beginning of the psu gene. this site changes the third amino acid of psu from ser to leu. this substitution does not destroy the binding of psu to th ... | 1995 | 7669349 |
| bacteriophage p4 dna replication. | replication of satellite phage p4 of escherichia coli is dependent on three phage-encoded elements: the origin (ori), a cis replication element (crr), and the product of the alpha gene, gp alpha. in p4 replication is origin-specific resulting in monomeric form i dna. dna synthesis requires chromosomally encoded proteins dna polymerase iii holoenzyme, ssb, dna gyrase and probably topoisomerase i; host-encoded initiation and priming functions are dispensable. the alpha protein is multifunctional i ... | 1995 | 7669353 |
| control of transcription termination by an rna factor in bacteriophage p4 immunity: identification of the target sites. | prophage p4 immunity is elicited by a short, 69-nucleotide rna (ci rna) coded for within the untranslated leader region of the same operon it controls. ci rna causes termination of transcription that starts at the promoter ple and prevents the expression of the distal part of the operon that codes for p4 replication functions (alpha operon). in this work, we identify two sequences in the untranslated leader region of the alpha operon, seqa and seqc, that are the targets of the p4 immunity factor ... | 1995 | 7883698 |
| 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 ... | 1994 | 7914347 |
| a new gene of bacteriophage p4 that controls dna replication. | bacteriophage p4 replication may result in either a lytic cycle or plasmid maintenance, depending on the presence or absence, respectively, of helper phase p2 genome. bacteriophage p4 dna replication depends on the product of gene alpha, which has origin recognition, primase, and helicase activities. an open reading frame with the coding capacity for a protein of 106 amino acids (orf106) is located upstream of the alpha gene. genes orf106 and alpha are transcriptionally coregulated. three amber ... | 1994 | 7928967 |
| phage p4 dna replication in vitro. | phage p4 dna is replicated in cell-free extracts of escherichia coli in the presence of partially purified p4 alpha protein [krevolin and calendar (1985), j. mol. biol. 182, 507-517]. using a modified in vitro replication assay, we have further characterized this process. analysis by agarose gel electrophoresis and autoradiography of in vitro replicated molecules demonstrates that the system yields supercoiled monomeric dna as the main product. electron microscopic analysis of in vitro generated ... | 1994 | 8029013 |
| active dna topoisomerase ii with minimum molecular mass from regenerating rat liver. | we have purified the type ii dna topoisomerase from regenerating rat liver. the purified topoisomerase ii migrated as two bands with molecular masses of 70 kda and 55 kda on sds-page. immunoblotting analysis using antiserum against rat topoisomerase ii gene product expressed in escherichia coli suggested that the two bands on sds-gel are proteolytic products of the intact 173 kda form. however, these products retained the enzyme activities such as catenation and relaxation of supercoiled circula ... | 1994 | 8038715 |
| molecular cloning and characterization of bacteriophage p2 genes r and s involved in tail completion. | the sequences of two previously known tail genes, r and s, of the temperate bacteriophage p2 and the sequence of an additional open reading frame (orf-30) located between s and v, were determined. amber mutations mapping within r and s, ram3, ram42, ram23, sam75, and sam89 were sequenced and found to be within their corresponding open reading frames. we constructed overproducing plasmids for r and s and identified these proteins by sds-page of whole-cell lysates and coomassie blue staining. the ... | 1994 | 8178426 |
| bacteriophage p2 and p4 assembly: alternative scaffolding proteins regulate capsid size. | the capsid protein of bacteriophage p2, encoded by the n gene, can assemble into icosahedral capsids of two possible sizes, with diameters of 60 and 45 nm, respectively. only the larger capsid is used by p2 itself, but the smaller one is exploited by the satellite phage p4. we have analyzed the assembly products of gpn expressed in vivo from a plasmid, i.e., in the absence of any other phage proteins, and find that gpn alone forms closed shells of both sizes, although with poor efficiency. coexp ... | 1994 | 8178454 |
| 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 ... | 1993 | 8246844 |
| phage p4 alpha protein is multifunctional with origin recognition, helicase and primase activities. | alpha protein of satellite phage p4 of escherichia coli is multifunctional in p4 replication with three activities. first, the protein (subunit m(r) = 84,900) complexes specifically the p4 origin and the cis replication region required for replication. alpha protein interacts with all six type i repeats (tgttcacc) present in the origin. second, associated with the alpha protein is a dna helicase activity that is fueled by hydrolysis of a nucleoside 5' triphosphate. all common ntps except utp and ... | 1993 | 8253092 |
| 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 ... | 1993 | 8253674 |
| 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 ... | 1993 | 8503180 |