Topic
Lambda phage
About: Lambda phage is a research topic. Over the lifetime, 1609 publications have been published within this topic receiving 84675 citations. The topic is also known as: Enterobacteria phage lambda.
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TL;DR: A genome-scale forward-genetics screen for host-dependencies of the latently-infecting bacteriophage lambda identifies two highly conserved pathways involved in tRNA thiolation—one pathway is required for efficient lambda replication, while the other has anti-viral properties inhibiting lambda replication.
Abstract: Latently infecting viruses are an important class of virus that plays a key role in viral evolution and human health. Here we report a genome-scale forward-genetics screen for host-dependencies of the latently-infecting bacteriophage lambda. This screen identified 57 Escherichia coli (E. coli) genes—over half of which have not been previously associated with infection—that when knocked out inhibited lambda phage's ability to replicate. Our results demonstrate a highly integrated network between lambda and its host, in striking contrast to the results from a similar screen using the lytic-only infecting T7 virus. We then measured the growth of E. coli under normal and infected conditions, using wild-type and knockout strains deficient in one of the identified host genes, and found that genes from the same pathway often exhibited similar growth dynamics. This observation, combined with further computational and experimental analysis, led us to identify a previously unannotated gene, yneJ, as a novel regulator of lamB gene expression. A surprising result of this work was the identification of two highly conserved pathways involved in tRNA thiolation—one pathway is required for efficient lambda replication, while the other has anti-viral properties inhibiting lambda replication. Based on our data, it appears that 2-thiouridine modification of tRNAGlu, tRNAGln, and tRNALys is particularly important for the efficient production of infectious lambda phage particles.
86 citations
TL;DR: An in vitro assay for measuring the activity of the phage lambda A-gene product has been developed and a method is suggested by which this A protein-dependent in vitro system might be manipulated to analyze the mechanism of reforming the lambda cohesive termini during chromosome assimilation into phage precursors.
Abstract: An in vitro assay for measuring the activity of the phage lambda A-gene product has been developed. The assay is based on the observation that A-donor extracts complement A minus extracts for packaging of exogenous immature lambda DNA into phage particles. A partial purification of the A-gene product activity using this assay is presented. A method is suggested by which this A protein-dependent in vitro system might be manipulated to analyze the mechanism of reforming the lambda cohesive termini during chromosome assimilation into phage precursors.
86 citations
TL;DR: A transcription termination site occurs between the promoter for late gene expression of bacteriophage lambda and the late genes themselves and it is proposed that the lambda Q gene product controlsLate gene expression by over-coming this termination barrier.
Abstract: A transcription termination site occurs between the promoter for late gene expression of bacteriophage lambda and the late genes themselves. It is proposed that the lambda Q gene product controls late gene expression by over-coming this termination barrier.
85 citations
TL;DR: Transduction analysis with lambda phages carrying the chromosomal fragment of the tnaA-gyrB region suggested that one of the mutations, nal-31, was located on the gyrB gene.
Abstract: In Escherichia coli K-12 mutants which had a new nalidixic acid resistance mutation at about 82 min on the chromosome map, cell growth was resistant to or hypersusceptible to nalidixic acid, oxolinic acid, piromidic acid, pipemidic acid, and novobiocin. Deoxyribonucleic acid gyrase activity as tested by supercoiling of lambda phage deoxyribonucleic acid inside the mutants was similarly resistant or hypersusceptible to the compounds. The drug concentrations required for gyrase inhibition were much higher than those for cell growth inhibition but similar to those for inhibition of lambda phage multiplication. Transduction analysis with lambda phages carrying the chromosomal fragment of the tnaA-gyrB region suggested that one of the mutations, nal-31, was located on the gyrB gene.
84 citations
TL;DR: Through transductional analysis and temperature reversion experiments, it was demonstrated that the grpE280 mutation is responsible for both the inability of lambda to replicate at any temperature tested and the lack of colony formation at high temperature.
Abstract: We have identified the grpE gene product as the B25.3 heat shock protein of Escherichia coli on the following evidence: (i) a protein similar in size and isoelectric point to B25.3 was induced after infection of UV-irradiated bacteria by lambda grpE+ transducing phage, (ii) mutant phage lambda grpE40, isolated by its inability to propagate on grpE280 bacteria, failed to induce the synthesis of the B25.3 protein, and (iii) lambda grpE+ revertants, derived from phage grpE40 as able to propagate on grpE280 bacteria, simultaneously recovered the ability to induce synthesis of the B25.3 protein. In addition, we show that E. coli bacteria carrying the grpE280 mutation are temperature sensitive for bacterial growth at 43.5 degrees C. Through transductional analysis and temperature reversion experiments, it was demonstrated that the grpE280 mutation is responsible for both the inability of lambda to replicate at any temperature tested and the lack of colony formation at high temperature. At the nonpermissive temperature the rates of synthesis of DNA and RNA were reduced in grpE280 bacteria.
84 citations