New insights into the journey of lipoproteins in the cell envelope of Escherichia coli : disorder matters
(2021)
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- Authors
- Supervisors
- Jean-François, Collet
- Abstract
- The cell envelope is essential for bacterial survival, as it forms a protective barrier that shelters the cell from its environment. This envelope consists of an outer and an inner membrane; both membranes are separated by the periplasm. In the periplasm, a mesh-like layer called peptidoglycan, or murein, is present and is important for cell shape and the protection against osmotic shock. The cell envelope includes three groups of proteins. During my thesis, I focused on studying one of these groups, which is lipoproteins. Lipoproteins, as their name subtly suggest, are globular proteins that are covalently linked to a lipid moiety which anchors them in one of the two membranes. This subset of proteins is involved in a wide range of vital bacterial processes. Lipoproteins can be retained in the inner membrane (IM) or can be transported to the outer membrane (OM). The sorting and targeting of lipoproteins between the two membranes is controlled by the Lol (Localization of lipoproteins) system. In this thesis, I show that lipoprotein sorting is affected by the presence of an intrinsically disordered region, that we call a linker, that is present at the N-terminal of half OM lipoproteins. First, I show that deleting the linker re-routes OM lipoproteins to the IM, which has functional consequences. Moreover, I found that the length, but not the sequence, of this linker is important for correct lipoprotein sorting, on the condition that the linker stays unstructured. Second, I provide mechanistic details on the function of the linker, showing that the disordered region works in a Lol-dependent manner. Finally, I propose a model where the linker optimizes OM targeting as well as the surface exposure of lipoproteins.
- Affiliations
Citations
El-Rayes, J. (2021). New insights into the journey of lipoproteins in the cell envelope of Escherichia coli : disorder matters. https://hdl.handle.net/2078.5/25147