Deutsch Intern
    SPP 1316

    Fuchs TM Salmonella Project

    Regulation and in vivo relevance of myo-inositol utilization by Salmonella enterica serovar Typhimurium

    PI: Prof. Dr. Thilo M. Fuchs

    Ph. D. student: Dipl.-Biol. Johannes Rothhardt

    This research project will focus on the link between the virulence of Salmonella enterica serovar Typhimurium (S. Typhimurium) and its capability to utilize myo-inositol (MI). All iol genes involved in this pathway are localized on a 22.6 kb genomic island (GEI4417/4436) that has recently been characterized in the applicant’s group. An extended lag phase of 60 hours and a bistable phenotype appeared as a unique feature of S. Typhimurium growth in the presence of MI. Studies with enteritis models performed in other laboratories demonstrated a significant contribution of MI-utilization to a Salmonella infection. The S. enterica-specific factor STM4423, a novel positive regulator, is essential for growth on MI and acts on the iolE promoter. The putative glycohydrolase SrfJ and the predicted isomerase IolI2 are hypothesized to play a key role in initiating MI degradation in vivo.

    The following aspects will be addressed:

    Response of PSTM4423 and PiolE (WP1): This work package will study the transcription initiation sites of these promoters, measure their transcriptional response to a variety of environmental stimuli by flow cytometry and a bioluminescence reporter, and investigate the putative promoter binding activity of SsrB.

    Role of SrfJ and IolI2 (WP2): The biochemical activity of both enzymes will be determined, and the phenotype of the respective deletion mutants will be analysed. The substrate spectrum of Salmonella with respect to MI precursors will be investigated.

    MI utilization by S. Typhimurium in vivo (WP3): We will study the effect of iol gene deletions on intracellular growth and proliferation within nematodes. The induction of iol promoters in cultured cells, in C. elegans, and in mice will be monitored using luciferase reporter fusions, and an in vivo imaging system. 13C-isotopologue flux analysis will analyse the utilization of MI in vivo.