The catabolite gene activation system ofE.coli may be directly involved in regulation of bacteriophage λ development (original) (raw)
Related papers
Transcription of a bacteriophage lambda DNA site blocks growth of Escherichia coli
Journal of Bacteriology, 1990
The rap mutation in Escherichia coli prevents the growth of bacteriophage lambda. Phage mutations that overcome rap inhibition (bar) have been mapped to loci in the pL operon. We cloned and sequenced three mutations in two of these loci: barIa to the left arm of the lambda attachment site (attP) and barII in the ssb (ea10) gene. The mutations represent single base-pair changes within nearly identical 16-base-pair DNA segments. Each mutation disrupts a sequence of dyad symmetry within the segment. Plasmids carrying a bar+ sequence downstream to an active promoter are lethal to rap, but not rap+, bacteria. The bar sequences isolated from the lambda bar mutants are not lethal. We synthesized a minimal lambda barIa+ sequence, 5'-TATATTGATATTTATATCATT, and cloned it downstream to an inducible promoter. When transcribed, this sequence is sufficient to kill a rap strain.
Methods in Molecular Biology, 2009
Recent studies have established that the most abundant life form, that of phages, has had major influence on the biosphere, bacterial evolution, bacterial genome, and lateral gene transmission. Importantly the phages have served and continue to serve as valuable model systems. Such studies have led to a renewed interest and activity in the study of phages and their genomes. In order to determine the details of the involvement of phages in these important processes and activities, it is critical to assign specific functions to the phage gene products. The initial functional and gene assignments can be made by general mutagenesis of the phage genomes and of these specific gene products. A very informative mutagenic protocol that has found renewed interest is that using hydroxylamine. This mutagenic protocol has been used to obtain gene mutations involved in the lysogenic cycle of the Salmonella enterica serovar Anatum var. 15+ phage ε 34 (hereafter phage ε 34 ) and to isolate conditional lethal mutants of phage ε 34 . A similar protocol using plasmid is also described. A plate complementation method is presented to determine quickly the number of genes which are present in the population of mutations isolated from hydroxylamine mutagenesis.
FEMS Microbiology Letters, 1996
It was demonstrated previously that a mutation, rpoA341, in the gene encoding the a subunit of Escherichiu coli RNA polymerase prevents lysogenization by bacteriophage h. The rpoA341 allele is known to be responsible for impaired transcription of some positively regulated E. coli chromosomal operons. Here we demonstrate that the inhibition of lysogenization of the rpoA341 mutant is a result of drastically decreased transcription from positively regulated phage promoters. We were unable to detect any transcripts originating from the CII-activated pz, pi and paQ promoters (important for lysogenic development) in, the phage-infected rpoA341 mutant, in contrast to an otherwise isogenic rpoA+ strain. The results are discussed in the light of other reports showing that activation of the pa promoter by CII protein in vitro is decreased only about fivefold when the native a subunit is replaced by truncated a polypeptides.
Phage Genetic Sites Involved in λ Growth Inhibition by the Escherichia Coli Rap Mutant
Genetics, 1989
T h e rap mutation of Escherichia coli prevents the growth of bacteriophage X. We have isolated phage mutants that compensate for the host deficiency. T h e mutations, named bar, were genetically located to three different loci of the X genome: b a d in the attP site, barll in the cIIZ ea10 region, and barIII within or very near the imm434 region. T h e level of X leftward transcription correlates with rap exclusion. Phage X mutants partially defective in the PL promoter or in pL-transcript antitermination showed a Bar-phenotype. Conversely, mutants constitutive for transcription from the PI or pL promoters were excluded more stringently by rap bacteria. We conclude that rap exclusion depends on the magnitude of transcription through the wild type bar loci in the phage genome.
Phage Genetic Sites Involved in X Growth Inhibition by the Escherichia coli rap Mutant
1989
The rap mutation of Escherichia coli prevents the growth of bacteriophage X. We have isolated phage mutants that compensate for the host deficiency. The mutations, named bar, were genetically located to three different loci of the X genome: bad in the attP site, barll in the cIIZ ea10 region, and barIII within or very near the imm434 region. The level of X leftward transcription correlates with rap exclusion. Phage X mutants partially defective in the PL promoter or in pL-transcript antitermi- nation showed a Bar- phenotype. Conversely, mutants constitutive for transcription from the PI or pL promoters were excluded more stringently by rap bacteria. We conclude that rap exclusion depends on the magnitude of transcription through the wild type bar loci in the phage genome.
1993
A cryptic promoter, designated P.,D initiates transcription within the OR region of bacteriophage A. Transcription from P. proceeds in the direction of the cI repressor gene from sites 46 and 48 bp preceding the PRM transcription start site. P, is likely to compete with both PR and PRM for formation of open complexes, since it is only active when PR is mutated and can be suppressed by mutations that increase PRM activity. In addition, transcription initiation at P, is blocked by A repressor. Kinetic analysis of relative abundance of the products of in vitro transcription indicated that P, was approximately 1/3 as strong as PRM. However, a P0-mutation had little effect on KBkf (the association rate constant) for PRM. These observations can be explained by the finding that open complexes formed at P,. are relatively unstable (half-life = 20 to 25 min). Dissociation of RNA polymerase from P., allows additional open complexes to form at PR or PRM, and thus the apparent strength of P,. d...
Gene regulation at the right operator (OR) of bacteriophage l
1980
In a X lysogen, transcription of the repressor gene, c1, initiates at the promoter P,, (see, for example, Reichardt & Kaiser, 197 1). Construction of a hybrid operon is described in which this promoter directs transcription of the trpA and la& genes permitting facile analysis of the regulation of P,, in viva. As reported previously , low levels of repressor stimulate P,, while higher levels of repressor turn it off. We report that mutations which render P,, insensitive to turnoff by repressor are found in Oa3, an operator site which overlaps P,,.