Julia Bürger

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C4 In vivo expression analysis of virulence proteins of Salmonella Typhimurium in macrophages and mouse infection models

Principal investigator
Wolfgang Hillen

Mentor
Frederik Börnke

PhD exam: 25.04.2013

In vivo expression analysis of virulence proteins of Salmonella Typhimurium in macrophages and mouse infection models

Salmonella Typhimurium is a facultative intracellular Gram negative bacterium which causes acute gastroenteritis in humans and lethal infections in BALB/c mice. Hence, it is subject of extensive research and serves as a model organism for pathogen-host interactions. Interestingly, to date exists only less information about the protein pattern of virulence factors in infection models. Therefore, it is necessary to study the protein expression of virulence factors for a better understanding of the pathogenicity of S. Typhimurium.
The aim of our group is to develop a new strategy to analyze the protein expression of virulence factors of S. Typhimurium, in in vivo models by using the Tet-System. For that purpose we will use a 17mer oligopeptide tag called TIP (Transcription inducing peptide) that induces Tet repressor controlled transcription. The peptide encoding sequence will be chromosomally fused to the gene of interest. In the first part of the project indicator strains with a Tet controlled reporter gene expression (GFP or luciferase) will be constructed, which should allow the discrimination between less, middless and high expressed fusion proteins. Afterwards we will analyze the protein expression in vivo during intracellular growth in cell culture or mouse infection models. This will provide an opportunity to monitor gene expression at the protein level and help to understand the pathogenicity of this organism.

Figure: Schematic presentation of an in vivo system to analyze the expression of virulence proteins in S. Typhimurium. The bacteria cell is depicted as an oval. The arrows indicate the respective gene. A dark green rectangle with an orange arrow shows a C-terminal fusion of TIP to a virulence gene (gene x). The Tet controlled promoter region is described as a grey rectangle and the Tet-Repressor as two blue ovals and circles. The expressed TIP fusion protein is shown as a green oval with an orange line. (A) In the absence of the TIP fusion protein the expression of the reporter gene is repressed by the Tet Repressor. (B) After expression of the TIP tagged virulence gene, Tet-Repressor is induced followed by expression of the reporter gene.

 

Publications

Georgi, C., Bürger, J., Hillen, W. and Berens C. (2012). Promoter Strength Driving TetR Determines the Regulatory Properties of Tet-Controlled Expression Systems. PLoS One 7(7), e41620.

 

Presentations

July 2012 4th Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
In vivo analysis of Salmonella virulence factor expression: How to create a novel reporter system
Talk
     
October 2011 First International SFB 796 Conference: Mechanisms of viral host cell manipulations: from plants to humans, Bamberg, Germany
Creating a sensitiv reporter system for analysing the expression of Salmonella virulence factors in macrophages and mouse infection models
Poster
     
July 2011 3rd Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
In vivo analysis of Salmonella virulence factor expression: How to create a novel reporter system
Talk
     
July 2011 3nd Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
Creating a sensitiv reporter system for analysing the expression of Salmonella virulence factors in macrophages and mouse infection models
Poster
     
September 2010 2nd Annual Retreat, Erlangen School of Molecular Communication, Kloster Banz, Bad Staffelstein, Germany
A reporter system for the in vivo analysis of Salmonella virulence factor expression
Talk
     
September 2009 First Annual Retreat, Erlangen School of Molecular Communication, Schloss Atzelsberg, Atzelsberg, Germany
A reporter system for the in vivo analysis of Salmonella virulence factor expression
Talk