@phdthesis{Wagner2021,
  author    = {Wagner, Rabea Marie},
  title     = {The Bacterial Exo- and Endo-Cytoskeleton Spatially Confines Functional Membrane Microdomain Dynamics in \(Bacillus\) \(subtilis\)},
  doi       = {10.25972/OPUS-21745},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217458},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Cellular membranes form a boundary to shield the inside of a cell from the outside. This is of special importance for bacteria, unicellular organisms whose membranes are in direct contact with the environment. The membrane needs to allow the reception of information about beneficial and harmful environmental conditions for the cell to evoke an appropriate response. Information gathering is mediated by proteins that need to be correctly organized in the membrane to be able to transmit information. Several principles of membrane organization are known that show a heterogeneous distribution of membrane lipids and proteins. One of them is functional membrane microdomains (FMM) which are platforms with a distinct lipid and protein composition. FMM move within the membrane and their integrity is important for several cellular processes like signal transduction, membrane trafficking and cellular differentiation. FMM harbor the marker proteins flotillins which are scaffolding proteins that act as chaperones in tethering protein cargo to FMM. This enhances the efficiency of cargo protein oligomerization or complex formation which in turn is important for their functionality. The bacterium Bacillus subtilis contains two flotillin proteins, FloA and FloT. They form different FMM assemblies which are structurally similar, but differ in the protein cargo and thus in the specific function. In this work, the mobility of FloA and FloT assemblies in the membrane was dissected using live-cell fluorescence microscopy techniques coupled to genetic, biochemical and molecular biological methods. A characteristic mobility pattern was observed which revealed that the mobility of both flotillins was spatially restricted. Restrictions were bigger for FloT resulting in a decreased diffusion coefficient compared to FloA. Flotillin mobility depends on the interplay of several factors. Firstly, the intrinsic properties of flotillins determine the binding of different protein interaction partners. These proteins directly affect the mobility of flotillins. Additionally, binding of interaction partners determines the assembly size of FloA and FloT. This indirectly affects the mobility, as the endo-cytoskeleton spatially restricts flotillin mobility in a size-dependent manner. Furthermore, the extracellular cell wall plays a dual role in flotillin mobility: its synthesis stimulates flotillin mobility, while at the same time its presence restricts flotillin mobility. As the intracellular flotillins do not have spatial access to the exo-cytoskeleton, this connection is likely mediated indirectly by their cell wall-associated protein interaction partners. Together the exo- and the endo-cytoskeleton restrict the mobility of FloA and FloT. Similar structural restrictions of flotillin mobility have been reported for plant cells as well, where the actin cytoskeleton and the cell wall restrict flotillin mobility. These similarities between eukaryotic and prokaryotic cells indicate that the restriction of flotillin mobility might be a conserved mechanism.},
  subject      = {Heubacillus},
  language  = {en}
}