Project description:The Escherichia coli strain Nissle 1917 (EcN) is used as a probiotic for the treatment of certain gastrointestinal diseases in several European and non-European countries. In vitro studies showed EcN to efficiently inhibit the production of Shiga toxin (Stx) by Stx producing E. coli (STEC) such as Enterohemorrhagic E. coli (EHEC). The occurrence of the latest EHEC serotype (O104:H4) responsible for the great outbreak in 2011 in Germany was due to the infection of an enteroaggregative E. coli by a Stx 2-encoding lambdoid phage turning this E. coli into a lysogenic and subsequently into a Stx producing strain. Since EHEC infected persons are not recommended to be treated with antibiotics, EcN might be an alternative medication. However, because a harmless E. coli strain might be converted into a Stx-producer after becoming host to a stx encoding prophage, we tested EcN for stx-phage genome integration. Our experiments revealed the resistance of EcN towards not only stx-phages but also against the lambda phage. This resistance was not based on the lack of or by mutated phage receptors. Rather the expression of certain genes (superinfection exclusion B (sieB) and a phage repressor (pr) gene) of a defective prophage of EcN was involved in the complete resistance of EcN to infection by the stx- and lambda phage. Obviously, EcN cannot be turned into a Stx producer. Furthermore, we observed EcN to inactivate phages and thereby to protect E. coli K-12 strains against infection by stx- as well as lambda-phages. Inactivation of lambda-phages was due to binding of lambda-phages to LamB of EcN whereas inactivation of stx-phages was caused by a thermostable protein of EcN. These properties together with its ability to inhibit Stx production make EcN a good candidate for the prevention of illness caused by EHEC and probably for the treatment of already infected people.

2018-06-14 | GSE109932 | GEO

Cao2010 - Epigenetic state of lysogeny in phage lambda

Project description:References: 1. Xiaomei Zhu, Lan Yin, Leroy Hood, David Galas and Ping Ao, Efficiency, Robustness and Stochasticity of Gene Regulatory networks in Systems biology: Lambda switch as a working example, 2006. 2. Adam Arkin, John Ross and Harley H. McAdams, Stochastic kinetic analysis of developmental pathway bifurcation in phage lambda-infected Escherichia coli cells, 1998, Genetics, 149: 1633-1648. 3. GenBank sequence: NC_001416 is the whole genome sequence of phage lambda.

2005-01-01 | MODEL1308080003 | BioModels

High resolution view of bacteriophage lambda gene expression by ribosome profiling

Project description:Bacteriophage lambda is one of the most extensively studied organisms, and has been a primary model for understanding basic modes of genetic regulation. Here we examine the progress of lambda gene expression during phage development by ribosome profiling, and thereby provide a very high resolution view of lambda gene expression. The known genes are expressed in a predictable fashion, authenticating the analysis. But many previously unappreciated potential open reading frames become apparent in the expression analysis, revealing an unexpected complexity in the pattern of lambda gene function. We chose temperature induction of the classic cI857 repressor mutation in a lysogen of E. coli MG1655 in order to synchronize the lytic process, sampling the lysogen and control non-lysogen both before and 2, 5, 10, and 20 minutes after shifting the temperature from 32M-BM-0 to 42M-BM-0. The last sample time was chosen to be before any significant cell lysis, but during the later stages of lytic gene expression. Total protected nucleotides within open reading frames were summed to determine the density of translation of each reading frame. We take this number to indicate the overall rate of translation, although obviously this assumes that pauses in translation do not excessively affect the overall rate. Since the expression level is not normalized for the copy number of the replicating phage DNA, it thus encompasses both the effect of DNA template availability on mRNA synthesis and the efficiency of utilization of messengers by ribosomes.

2013-07-01 | E-GEOD-47509 | biostudies-arrayexpress

Lambdavirus lambda

Project description:PacBio Low Input Sequencing

| PRJNA272509 | ENA