Québatte, Maxime. Uncovering the transcriptional control of "Bartonella henselae" host adaptation factors. 2014, PhD Thesis, University of Basel, Faculty of Science.
Official URL: http://edoc.unibas.ch/diss/DissB_10863
In the research article I, we describe the adaptive response of B. henselae during host cell infection and reveal the central role of the BatR/BatS two component system (TCS) for the coordination of this response. We demonstrate that this TCS is activated at the physiological pH of blood (pH7.4) and is required for the up-regulation of a critical cluster of genes that includes the genes encoding the VirB/D4 T4SS and its cognate secreted effectors (Beps). In the research article II, we present the near complete expressed proteome of B. henselae under conditions that mimic host-interaction, using a combination of saturated transcriptome profiling by RNA-seq and directed shotgun proteomics. Of particular interest, the complete membrane proteome coverage achieved reveals the dramatic re-organization taking place in this compartment during the infection process, with the differential regulation of a large panel of autotransporters, adhesins and hemin binding proteins as well as all components of the VirB/D4 T4SS. In the research article III, we describe how a dual regulatory input controls the expression of the VirB/D4 T4SS and its secreted effector proteins. We demonstrate that additionally to the BatR/BatS TCS, the expression of this host adaptation factors requires the alternative sigma factor RpoH1, which is itself controlled by the stringent response (SR) components SpoT and DksA. In contrast to the VirB/D4 T4SS, which is needed at the early stage of mammalian host colonization and require the SR components for its full expression, we show that SpoT and DksA negatively regulate the Trw T4SS, which is required for erythrocyte invasion at a later stage of the host infection. In the research article IV, we demonstrate the possible use of B. henselae to deliver DNA into human cells through its VirB/D4 T4SS and to generate stable transgenic cell lines. We propose that due to its ancestral abilities as conjugation system, this specialized transkingdom secretion system has potential for the development of new in vivo gene therapy approaches in humans.
Together, these results constitute the first comprehensive analysis of B. henselae pathogenicity factors during host cell infection. Besides the elucidation of very specific regulatory aspects for the expression of the VirB/D4 T4SS and its secreted substrates, this work allows us to propose a general model for B. henselae host adaptation strategy throughout its infection cycle. In our model, the BatR/BatS pH-dependent signaling is used to distinguish between the arthropod and the mammalian host environment whereas the SR signaling allows the modulation of the bacterial response between the early and the late colonization stages of the mammalian host.
|Committee Members:||Jenal, Urs|
|Faculties and Departments:||05 Faculty of Science > Departement Biozentrum > Infection Biology > Molecular Microbiology (Dehio)|
|Bibsysno:||Link to catalogue|
|Number of Pages:||159 S.|
|Last Modified:||30 Jun 2016 10:56|
|Deposited On:||28 Jul 2014 13:27|
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