Berlin 2024 – scientific programme

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BP: Fachverband Biologische Physik

BP 8: Poster Session Ia

BP 8.20: Poster

Monday, March 18, 2024, 18:00–20:30, Poster C

The Role of Perilipin 5 for the Contact Sites between Lipid Droplets and Bilayer: Protein Tether, or Lipid Bridge? — •Shima Asfia, Mahsa Mohammadian, Ralf Seemann, and Jean-Baptiste Fleury — Department of Experimental Physics and Center for Biophysics, Saarland University, Germany

Lipid droplets (LDs) play a pivotal role in cellular energy storage and supplying components for the structure of organelle membranes. As the biology of lipid droplets relies on close coordination and communication with other cellular organelles, it is important to take a look at this interaction. In particular, the role of the protein Perilipin 5 (PLIN5), which is known as a mediator in regulating LDs dynamics and metabolism in cells is of interest. To investigate the impact of PLIN5 on the formation of contact sites between LDs and a bilayer, LDs (triolein oil droplets) surrounded by a phospholipid monolayer with and without PLIN5 are brought in contact with single unilamellar vesicles (SUV)s with a composition close to the ER membrane. To detect different contact interactions of SUVs with the monolayer coating the LDs, the SUVs were double fluorescent labeled with a phospholipid Rhodamine dye in the bilayer and Cy5 dye in the core. Protein tethers can be assumed when the SUVs stay in contact with LDs via protein attachment; in this case, spots with both fluorescent dyes are observed on the surface of the LDs. Lipid bridges can be assumed when SUVs fuse to the LD monolayer, and a colored *Rhodamine ring* appears on the surface of LDs revealing that only the phospholipid dye of the SUVs merged with LDs monolayer.

Keywords: Lipid Droplet; Contact Site; Protein Tether; Lipid Bridge