The helper dependence of satellite bacteriophage P4: Which gene functions of bacteriophage P2 are needed by P4?

Six, Erich W.

doi:10.1016/0042-6822(75)90422-5

Cited by 111 publications

(53 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The phages and bacterial strains are described in Table 1. The culture media were L broth and L agar (42). Plasmid-containing strains were grown in media containing 50 jig of ampicillin per ml or 12.5 ,ug of tetracycline per ml.…”

Section: Methodsmentioning

confidence: 99%

Control of bacteriophage P2 gene expression: analysis of transcription of the ogr gene

1991

View full text Add to dashboard Cite

The bacteriophage P2 ogr gene encodes an 8.3-kDa protein that is a positive effector of P2 late gene transcription. The ogr gene is preceded by a promoter sequence (Pogr) resembling a normal Escherichia coli promoter and is located just downstream of a late transcription unit. We analyzed the kinetics and regulation of ogr gene transcription by using an ogr-specific antisense RNA probe in an Si mapping assay. During a normal P2 infection, ogr gene transcription starts from Pgr an intermediate time between the onset of early and late transcription. At late times after infection the ogr gene is cotranscribed with the late FETUD operon; the ogr gene product thus positively regulates its own synthesis from the P2 late promoter PF. Expression of the P2 late genes also requires P2 DNA replication. Complementation experiments and transcriptional analysis show that a nonreplicating P2 phage expresses the ogr gene from Pg, but is unable to transcribe the late genes.A P2 ogr-defective phage makes an increased level of ogr mRNA, consistent with autogenous control from Pogr. Transcription of the ogr gene in the prophage of a P2 heteroimmune lysogen is stimulated after infection with P2, suggesting that Pogr is under indirect immunity control and is activated by a yet-unidentified P2 early gene product during infection.Bacteriophage P2 belongs to a group of noninducible temperate phages of Escherichia coli that differ from the lambdoid phages in both gene organization and regulation (for reviews, see references 1 and 11). P2 early transcription is confined to the right half of the P2 chromosome (16) and initiates at two divergent promoters, P, and Pe, in the early control region (38). Transcription of the left half of the chromosome, where most of the phage morphogenesis genes are located, is induced later in infection (17). The P2 late genes are clustered into four transcription units based on the polar effects of amber mutations (29,46) (Fig. 1). Transcription of these operons depends on the host RNA polymerase (31), the P2 DNA replication genes A and B (17,28,29), and the P2 ogr gene (3,45). The four late operons are all expressed at the same time during a P2 infection, suggesting independent and coordinated transcription initiation from the late promoters (9,10,28). Late transcription initiates from sites that do not resemble promoters normally recognized by the host RNA polymerase (9, 10).The product of the P2 ogr gene is a 72-amino-acid basic protein (4,12,26,27)

show abstract

Section: Methodsmentioning

confidence: 99%

Control of bacteriophage P2 gene expression: analysis of transcription of the ogr gene

1991

View full text Add to dashboard Cite

show abstract

“…Strain C-2156 was used as a standard host for P2 dellS (11). The culture media were L broth and L agar (52). Plasmid-containing strains were grown in media containing 100 ,ug of ampicillin per ml (pBluescript SK+ and its derivatives) or 12.5 p,g of tetracycline per ml (pNB56).…”

Section: Methodsmentioning

confidence: 99%

Escherichia coli K-12 and B contain functional bacteriophage P2 ogr genes

et al. 1992

View full text Add to dashboard Cite

The bacteriophage P2 ogr gene encodes an essential 72-amino-acid protein which acts as a positive regulator of P2 late transcription. A P2 ogr deletion phage, which depends on the supply of Ogr protein in trans for lytic growth on Escherichia coli C, has previously been constructed. E. coli B and K-12 were found to support the growth of the ogr-defective P2 phage because of the presence of functional ogr genes located in cryptic P2-like prophages in these strains. The cryptic ogr genes were cloned and sequenced. The Escherichia coli rpoA109 mutation, which causes an amino acid substitution in the a subunit of the RNA polymerase, blocks transcription of the P2 late genes (21,56). This block is overcome by suppressor mutations in the P2 ogr gene (56); thus, it appears that Ogr interacts with the RNA polymerase ao subunit in initiation of transcription from the P2 late promoters. Interactions between the ac subunit and other positive regulatory proteins have been implied by the isolation of several rpoA mutations which affect the transcription of different positively regulated E. coli genes (22,25,44,47) and also by recent studies of the E. coli cyclic-AMP receptor protein (34, 35).As a part of our investigations concerning the Ogr protein function and the regulation of its gene, we have previously reported the construction of an ogr-defective mutant phage, P2 dellS, which carries a deletion in the C-terminal half of the ogr gene (9). P2 dellS grows lytically on E. coli C, the standard host for phage P2, only if the Ogr protein is provided in trans from an ogr-expressing plasmid, demonstrating that the ogr gene is essential for P2 lytic growth. In this paper, we report that E. coli B and K-12 strains are able to support growth of P2 dell5 and that this ability is due to the presence of chromosomally located ogr genes carried by cryptic prophages. The presence of an ogr gene in E. coli * Corresponding author. K-12 has recently also been demonstrated by Barreiro andHaggard-Ljungquist (4). When the P2 ogr gene is compared with the cryptic genes, there are few differences in the nucleotide sequences, and most of the differences are silent base substitutions. MATERIALS AND METHODSBacteria, phages, and plasmids. Bacterial strains, phages, and plasmids are listed in Table 1. Strain C-2156 was used as a standard host for P2 dellS (11). The culture media were L broth and L agar (52). Plasmid-containing strains were grown in media containing 100 ,ug of ampicillin per ml (pBluescript SK+ and its derivatives) or 12.5 p,g of tetracycline per ml (pNB56).Burst size determination. Bacteria were grown in L broth at 37°C to an optical density at 600 nm of 0.2, collected by centrifugation at 9,000 x g for 2 min, and resuspended in one-third the original volume of ice-cold L broth containing 5 mM CaCl2. The cells were infected with P2 dellS at a multiplicity of infection of 0.1 and then incubated at 37'C for 8 min for adsorption of the phage. The infected cells were collected by centrifugation at 9,000 x g for 2 min at 4°C and washed ...

show abstract

“…P4 facilitates its lytic growth in two ways: (i) by derepressing a P2 prophage, which leads to P2 DNA replication and subsequent expression of the P2 late genes; and (ii) by directly activating the transcription of the P2 late genes in a process termed transactivation. P4 is also able to transactivate the late genes of a replication-deficient P2 helper (51,53,55). Transactivation is controlled by the P4 8 gene, which codes for a positive transcription factor that acts at the late promoters of the helper phage (8,9,48,55).…”

mentioning

confidence: 99%

“…1. In the lytic pathway, P4 must obtain the products of the P2 late genes in order to make the phage particle and lyse the bacterial host, Escherichia coli (51,52). Transcription of the P2 late genes in the absence of P4 requires P2 DNA replication and the product of the P2 ogr gene (8,9,18,37).…”

mentioning

confidence: 99%

A mutation of the transactivation gene of satellite bacteriophage P4 that suppresses the rpoA109 mutation of Escherichia coli

et al. 1990

View full text Add to dashboard Cite

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 a 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 the suppressor mutation in the ogr gene. Furthermore, we isolated and characterized four independent mutations in P4, called org, that suppress the E. coli rpoAl09 mutation by allowing P4 lytic growth using a P2 ogr+ helper. DNA sequence analysis revealed that the four independent org mutations are identical and that they occur in the P4 8 gene, which codes for a factor that positively regulates the transcription of the P2 and P4 late genes. 8 is predicted to Fig. 1. In the lytic pathway, P4 must obtain the products of the P2 late genes in order to make the phage particle and lyse the bacterial host, Escherichia coli (51, 52). Transcription of the P2 late genes in the absence of P4 requires P2 DNA replication and the product of the P2 ogr gene (8,9,18,37). P4 facilitates its lytic growth in two ways: (i) by derepressing a P2 prophage, which leads to P2 DNA replication and subsequent expression of the P2 late genes; and (ii) by directly activating the transcription of the P2 late genes in a process termed transactivation. P4 is also able to transactivate the late genes of a replication-deficient P2 helper (51,53,55). Transactivation is controlled by the P4 8 gene, which codes for a positive transcription factor that acts at the late promoters of the helper phage (8,9,48,55). When P4 uses a replicationdeficient helper, a functional 8 gene is essential for lytic multiplication (24, 55).Transcription of the late genes of bacteriophage P2 is dependent on the bacterial RNA polymerase (36). P2 late gene transcription is blocked by the E. coli rpoA109 mutation, which substitutes a histidine for a leucine residue in the a subunit of RNA polymerase (16,56). Dominant mutations of P2 were isolated that suppressed rpoA109 by restoring transcription of the P2 late genes, and these mutations defined the P2 ogr gene (6,10,56 during coinfection with a wild-type P2 helper (48). We report here the isolation and characterization of four independent P4 mutants that overcome the rpoA109-imposed block. MATERIALS AND METHODSMedia and buffers. L broth, which was used for growth of bacteria, contained 1% tryptone, 0.5% yeast extract, and 0.5 or 1% NaCl. LGCM, which was used for growing phage, contained L broth supplemented to 0.2% glucose, 1 mM CaCl2, and 2 mM MgCl2. LC agar, which was used for plating P2 and P4 phage, contained L broth supplemented to 2.5 mM CaCl2 and 1% agar. Antibiotics were added to media when necessary to a final concentration of 200 ,ug/ml for streptomycin, 50 ,ug/ml for ampicillin, and 15 ,ug/ml for tetracycline. P2 phage was...

show abstract

The helper dependence of satellite bacteriophage P4: Which gene functions of bacteriophage P2 are needed by P4?

Cited by 111 publications

References 24 publications

Control of bacteriophage P2 gene expression: analysis of transcription of the ogr gene

Control of bacteriophage P2 gene expression: analysis of transcription of the ogr gene

Escherichia coli K-12 and B contain functional bacteriophage P2 ogr genes

A mutation of the transactivation gene of satellite bacteriophage P4 that suppresses the rpoA109 mutation of Escherichia coli

Contact Info

Product

Resources

About