Lysophospholipids - underestimated molecules of the unique phospholipidome of Campylobacter jejuni

Abstract

In response to changes in their environment, bacteria need to change not only their protein repertoire, but also their phospholipid composition. A small fraction of the phospholipids in the bacterial membrane are lysophospholipids (LPLs). Although LPLs are minor phospholipid species of the bacterial cell membrane, in eukaryotic cells they are important signaling molecules. In some pathogenic bacteria, LPLs can be strongly increased under certain stress conditions, however, the biological function of LPLs in bacteria has not been investigated. The goal of the research described in this thesis was to determine the phospholipidome of C. jejuni under different environmental conditions and to assess the role of distinct (classes of) phospholipids in bacterial pathogenesis and/or stress adaptation. In Chapter 2, we provide an overview of the different LPLs species present in bacteria and summarize the knowledge about their role in bacterial adaptation, survival, invasion and host-microbe interaction. In Chapter 3, we for the first time investigated the nature of the phospholipids produced by C. jejuni under different growth conditions. In Chapter 4, we investigated the role of the C. jejuni membrane LPLs during bile salt exposure using an isogenic mutant defective in the phospholipase PldA. In Chapter 5, we focused on the potential role of LPLs as a novel virulence factor of C. jejuni. This work has leaded to the identification of the highly dynamic phospholipidome of the food-borne pathogen C. jejuni and that LPLs can be considered as novel virulence factor of this organism.