Project Reference: TRG27-BIO-MW1

Project title: The stringent response rewired: pathways of (p)ppGpp-dependent virulence in the opportunistic human pathogen, Pseudomonas aeruginosa. 

Project outline

Pseudomonas aeruginosa is an opportunistic pathogen that causes devastating disease in humans. The organism does so by using a ""coincidence circuit"" to integrate information about the population cell density (titrated by quorum sensing, ""QS"") and nutritional status (titrated by (p)ppGpp levels) to regulate virulence factor expression. From an anthropocentric viewpoint, this makes sense; after all, the bacteria are not inherently malevolent - they produce virulence factors as a means to an end to secure nutrients.

The MW team has recently been investigating the role(s) of (p)ppGpp in virulence in detail, and this has uncovered some surprising findings. First, P. aeruginosa seems to be ""wired up"" differently compared with E. coli (where most of the seminal work on (p)ppGpp was carried out). For example, deep RNAseq analyses revealed that (p)ppGpp controls the expression of a very different set of genes cf. E. coli. Moreover, we found that (p)ppGpp also controls a number of previously uncharacterized non-coding small RNAs, some of which appear to regulate virulence-associated transcripts and AMR . In parallel, Thermal Proteome Profiling uncovered that (p)ppGpp physically binds to a large number of novel protein targets in P. aeruginosa, again, indicating a completely different mode of action compared with E. coli.

The goal of this project is to establish how (p)ppGpp integrates with QS to stimulate virulence in P. aeruginosa. By combining molecular-genetic analyses with state-of-the-art 'omics and computational approaches, novel virulence assays, and protein chemistry-based analyses, we aim to identify and characterize key ""missing links"" in the associated signal transduction pathway(s). A previous PhD student used a similar set of approaches to identify a novel central ""integrator"" (denoted MexT) and we know that several other key regulatory inputs remain to be characterized. The project is therefore both feasible and potentially publication-rich.     

Principal Supervisor

Professor Martin Welch

Email address: mw240@cam.ac.uk

Department / Partner Institute: Biochemistry

Website: https://mw2409.wixsite.com/welch-lab

BBSRC strategic theme

Understanding the rules of life