The bacterial pathogen Helicobacter pylori persistently colonises the gastric mucosa of over half the world’s population causing gastritis, peptic ulceration and gastric adenocarcinoma, the third most common cause of cancer-related deaths worldwide. Pathogenic processes underlying severe clinical outcomes of H. pylori infection are multifactorial and not clearly defined, although several bacterial virulence determinants are recognised to be important. Of these, a number of secreted proteins and the specialised secretion machineries that mediate their export from the bacterial cell to the gastric mucosa have attracted particular research interest. These secretion systems provide a mechanism by which H. pylori can directly interact with host cells and initiate disease processes through subversion of normal host cellular function.
H. pylori strains are known to variably encode three different type IV secretion systems (T4SSs) with potential virulence function. Principal amongst these is the cag pathogenicity island-encoded T4SS which primarily functions to translocate the effector protein CagA directly into host gastric epithelial cells. The functional activity of the other two disease-associated T4SSs, Tfs3 and Tfs4, encoded by mobile integrative and conjugative elements (ICEs) is less well defined, in part due to lack of knowledge of the specific stimuli required to induce their activity and a clearly defined phenotype by which activity can be assessed.
Two projects are proposed:
1. Investigation into the regulation of the tfs-ICE-encoded T4SSs
This study will aim to determine the key stimuli for activation of the complement of tfs ICE genes and elucidate the regulatory network that controls their expression.
2. Investigation into the functional activity of the tfs4 ICE and tfs4 ICE-encoded T4SS
This study aims to define phenotypes associated with tfs+ H. pylori strains and investigate the activity of a subset of putative tfs ICE-encoded secreted proteins in the context of host epithelial cell interaction.
The research is multidisciplinary and techniques will include a broad range of molecular microbiology (PCR, cloning, mutagenesis, qRT-PCR), immunological (ELISA, Western blot) and protein biochemical methods (protein purification, functional assay, yeast-two-hybrid assay), H. pylori culture and in vitro models of infection (cell culture), bioimaging (epifluorescence microscopy), bioinformatics analyses and high-throughput reporter assay.
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Please email a CV with a covering letter to Dr Rob Delahay.