Uncovering the role of Macrophage Infectivity Potentiator (Mip) proteins in Pseudomonas aeruginosa (PA01) virulence

Scott, Benjamin (2022) Uncovering the role of Macrophage Infectivity Potentiator (Mip) proteins in Pseudomonas aeruginosa (PA01) virulence. Doctoral thesis, University of East Anglia.

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Abstract

Currently, in a clinical setting, Microbiologists face an ever-growing challenge in treating multidrug resistant bacterial infections using the conventional antibiotics currently at our disposal. One gram-negative ESKAPE pathogen, Pseudomonas aeruginosa, is currently listed at the top of the priority one pathogens by the World Health Organisation (WHO) that require urgent research and development of new antimicrobials. With a limited number of antibiotics currently in clinical trials, new drug targets are desperately needed, with recent investigations targeting bacterial virulence proteins. One promising virulence target are a group of proteins termed Macrophage Infectivity Potentiators (Mips). These proteins belong to the FK506 binding protein family of peptidyl-prolyl cis/trans isomerases (PPIases). Mip proteins have been discovered in several gram-negative pathogens including Legionella pneumophila and Burkholderia pseudomallei, where they have been shown to be essential in the invasion of macrophages, in murine-infection models, and in several other virulence determinants. Inhibition of these Mipproteins by FK506 or rapamycin reduces virulence of the pathogens drastically.

Here, we investigated whether Mip-like protein candidates exist in the P. aeruginosa genome. This study describes the identification and characterisation of three Mip-proteins, PaMip1, PaMip2 and PaMip3, that are required for the full virulence of P. aeruginosa in two in vivo models. To further unpick the pleiotropic functions of these PaMips, and understand how they may exert their virulence effects, we performed in vitro plate based virulence assays with Mip mutants which revealed attenuation in several important virulence processes including biofilm formation and twitching motility. To elucidate these phenotypes, RNA sequencing analysis was performed which revealed the significant downregulation in an unstudied cluster of genes associated with the Type Six Secretion System hcp-island III (T6SS HSI-III). Strains housing deletions in the T6SS HSI-III exhibited attenuation in in vivo infection models similar to the PaMip knockout strains.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User:	Kitty Laine
Date Deposited:	24 May 2023 13:37
Last Modified:	24 May 2023 13:37
URI:	https://ueaeprints.uea.ac.uk/id/eprint/92164
DOI:

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