Plant oils represent an energy-rich and carbon-dense group of hydrophobic compounds. These oils are not only of economic interest, but also play important, fundamental roles in plant growth and development. The subcellular storage compartments of neutral plant lipids are referred to as lipid droplets (LDs, also referred to as oleosomes or oil bodies). While they have long been considered relatively inert oil vessels, research in the last decade has revealed that LDs play far more dynamic roles in plant biology than previously appreciated, including transient neutral lipid storage, membrane remodeling, lipid signaling, and stress responses.
We are studying proteins associated with LDs to gain a better understanding of LD function across species and tissues. LD proteins are identified by label-free quantitative proteomics and cell biological tools.
In more detail, we have investigated a family of triacylglycerol lipases not involved in bulk degradation of oil but with more specialized functions in pollen tube growth and pathogen defense. Furthermore, we identified a scaffold protein, PUX10, that can recruit CDC48 to LDs and is involved in protein turnover. Most recently, we discovered two proteins of previously unknown function that can target LDs to the plasma membrane potentially creating an LD-plasma membrane interface.
Kretzschmar, F.K., Doner, N., Krawczyk, H.E., Scholz, P., Schmitt, K., Valerius, O., Braus, G., Mullen, R.T. and Ischebeck, T. (2019) Identification of low-abundant lipid droplet proteins in seeds and seedlings. Plant Physiology, doi: 10.1104/pp.19.01255. [Epub ahead of print]
Kretzschmar, F.K., Mengel, L.F., Müller, A., Schmitt, K., Blersch, K.F., Valerius, O., Braus, G., and Ischebeck, T. (2018) PUX10 is a lipid droplet-localized scaffold protein that interacts with CDC48 and is involved in the degradation of lipid droplet proteins. The Plant Cell. 30, 2137-2160.
Müller, A.O. and Ischebeck, T. (2018) Characterization of the enzymatic activity and physiological function of the lipid droplet-associated triacylglycerol lipase AtOBL1. New Phytologist, 217, 1062-1076.
Rotsch, A.H., Kopka, J., Feussner, I. and Ischebeck, T. (2017) Central metabolite and sterol profiling divides tobacco male gametophyte development and pollen tube growth into eight metabolic phases. The Plant Journal, 92, 129-146.
Müller, A. O., Blersch, K. F., Gippert, A. L., and Ischebeck, T. (2017) Tobacco pollen tubes - a fast and easy tool to study lipid droplet association of plant proteins. The Plant Journal 89, 1055-1064