Showing papers on "Lambda phage published in 2014"

Stochastic cellular fate decision making by multiple infecting lambda phage.

Abstract: Bacteriophage lambda is a classic system for the study of cellular decision making. Both experiments and mathematical models have demonstrated the importance of viral concentration in the lysis-lysogeny decision outcome in lambda phage. However, a recent experimental study using single cell and single phage resolution reported that cells with the same viral concentrations but different numbers of infecting phage (multiplicity of infection) can have markedly different rates of lysogeny. Thus the decision depends on not only viral concentration, but also directly on the number of infecting phage. Here, we attempt to provide a mechanistic explanation of these results using a simple stochastic model of the lambda phage genetic network. Several potential factors including intrinsic gene expression noise, spatial dynamics and cell-cycle effects are investigated. We find that interplay between the level of intrinsic noise and viral protein decision threshold is a major factor that produces dependence on multiplicity of infection. However, simulations suggest spatial segregation of phage particles does not play a significant role. Cellular image processing is used to re-analyse the original time-lapse movies from the recent study and it is found that higher numbers of infecting phage reduce the cell elongation rate. This could also contribute to the observed phenomena as cellular growth rate can affect transcription rates. Our model further predicts that rate of lysogeny is dependent on bacterial growth rate, which can be experimentally tested. Our study provides new insight on the mechanisms of individual phage decision making. More generally, our results are relevant for the understanding of gene-dosage compensation in cellular systems.

Application of recombinase gene bet as escherichia coli heterologous protein expression fusion tag

Abstract: The invention relates to a method of taking a recombinase gene bet from a lambda phage as a fusion tag. The method comprises the following step: by taking the recombinase gene bet from the lambda phage as the fusion tag, cloning nucleotide sequences of the elements such as six histidines, a bet gene, a TEV enzyme digestion site, a segment of stuffer fragment and the like to an escherichia coli expression carrier pET30a(+), so as to obtain a bet gene fusion expression carrier. A to-be-expressed target gene can be fused with six histidine tags and the bet gene in a reading frame by substituting the stuffer fragment, and is induced in escherichia coli to express, so as to obtain the protein fused with tag protein and target protein. The ratio of soluble ingredients of the target protein can be greatly improved by fusion expression.

Site-specific mutagenesis Lambda phage Int recombinant protein and preparation method thereof

Abstract: The invention discloses a site-specific mutagenesis Lambda phage Int recombinant protein and a preparation method thereof. The recombinant protein is obtained through site-specific mutagenesis of gene segment of the Lambda phage Int recombinant protein. The Lambda phage Int recombinant protein is transformed to be recombinant protein which can play activity under the influence of temperature. The recombinant protein is enabled not to start a DNA recombination reaction under a low temperature condition, and to start the DNA recombination reaction under a certain temperature condition, therefore, the DNA recombination reaction can be controlled. The recombination activity of an enzyme is influenced through temperature difference, large sample recombination reaction can be performed, and the flux of a recombined sample can be increased.