Dynamics of lipids in the yeast lipid droplets

The physical properties and chemical composition of lipid droplets inside cells of the yeast Cryptococcus curvatus were investigated using quasi-elastic neutron scattering and mass spectrometry with complementary surface modeling using 3D microscopy. With temperature decrease from 310 to 280 K, their phase remained fluid, i.e., the droplets remained in the physiological state, unlike synthetic lipid membranes that transition to a gel phase. The lipid dynamics in the droplet was described by a model implying diffusion of the lipid and its hydrocarbon chains. The diffusion coefficient of the lipid chains (274*10^-3 Angstrom^2/ps at 310 K) was much higher than that observed in a synthetic lipid membrane because of the larger volume (up to 12 Angstrom) for the local dynamics in the droplet. These physical properties were correlated with the types of lipids composing the droplet. Based on that, the lipid packing and resulting energetic value of the yeast droplets are discussed in relation to their usefulness as biofuels.