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: The thermal stabilities of mutant phage lambda repressors that have single amino acid replacements in the NH2-terminal domain have been studied by means of circular dichroism and differential scanning calorimetry and can be compared with the temperature-sensitive activity of the mutants in vivo.
Abstract: The thermal stabilities of mutant phage lambda repressors that have single amino acid replacements in the NH2-terminal domain have been studied by means of circular dichroism and differential scanning calorimetry. The variations in stability determined by these physical methods correlate with the resistance to proteolysis at various temperatures and can be compared with the temperature-sensitive activity of the mutants in vivo. In general, mutant proteins bearing solvent-exposed substitutions have thermal stabilities identical to wild type, whereas buried substitutions reduce stability. In one case, a single amino acid replacement increases the thermal stability of the repressor.
136 citations
TL;DR: The ftsH gene, previously shown to code for an essential inner membrane protein with putative ATPase activity, is identical to hflB, a gene involved in the stability of the phage cII activator protein, which may act as a chaperone, maintaining cII in a conformation subject to proteolysis via such a pathway.
Abstract: The lambda phage choice between lysis and lysogeny is influenced by certain host functions in Escherichia coli. We found that the frequency of lambda lysogenization is markedly increased in the ftsH1 temperature-sensitive mutant. The ftsH gene, previously shown to code for an essential inner membrane protein with putative ATPase activity, is identical to hflB, a gene involved in the stability of the phage cII activator protein. The lysogenic decision controlled by FtsH/HflB is independent of that controlled by the protease HflA. Overproduction of FtsH/HflB suppresses the high frequency of lysogenization in an hflA null mutant. The FtsH/HflB protein, which stimulates cII degradation, may be a component of an HflA-independent proteolytic pathway, or it may act as a chaperone, maintaining cII in a conformation subject to proteolysis via such a pathway. Suppressor mutations of ftsH1 temperature-sensitive lethality, located in the fur gene (coding for the ferric uptake regulator), did not restore FtsH/HflB activity with respect to lambda lysogenization.
136 citations
TL;DR: The unique structure of the N15 genome suggests that the large global population of bacteriophages may exhibit a much greater diversity of genomic architectures than was previously recognized.
134 citations
TL;DR: The common laboratory strain of bacteriophage lambda--lambda wild type or lambda PaPa--carries a frameshift mutation relative to Ur-lambda, the original isolate, which has expanded receptor specificity and adsorbs to Escherichia coli cells more rapidly.
Abstract: The common laboratory strain of bacteriophage lambda--lambda wild type or lambda PaPa--carries a frameshift mutation relative to Ur-lambda, the original isolate. The Ur-lambda virions have thin, jointed tail fibers that are absent from lambda wild type. Two novel proteins of Ur-lambda constitute the fibers: the product of stf, the gene that is disrupted in lambda wild type by the frameshift mutation, and the product of gene tfa, a protein that is implicated in facilitating tail fiber assembly. Relative to lambda wild type, Ur-lambda has expanded receptor specificity and adsorbs to Escherichia coli cells more rapidly.
133 citations
TL;DR: DNA synthesis of early sus (suppressor sensitive) mutants of phage λ in su − cells was studied by the density-gradient centrifugation method and it was found that superinfection of a heteroimmune lysogen by a sus P mutant fails to elicit the function required for replication of the superinfecting phage genome.
132 citations