Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Membrane proteins are vital for making cells responsive to environmental stimuli as well as in controlling the exchange of ions between the cytoplasm and the extracellular space. Both processes depend on proteins containing multiple transmembrane helices that rearrange during function. The development of a technology that allows resolving structural transitions in single membrane proteins by the use of ultra-short X-ray pulses from X-ray free electron lasers (X-FELs) will represent a significant advance in studies of membrane protein structure and dynamics. The successful use of X-FEL radiation for Structural Biology has been proven for nanocrystals. In contrast, the potential for a fully crystallization-independent analysis of large protein structures at the single molecule level has not been explored experimentally.
Engineered phospholipid nanodiscs (NDs), which are lipid-protein complexes surrounded by a helical protein belt of two membrane scaffold proteins (MSPs) provide a completely soluble nanoscale section of a lipid bilayer designed for functional investigations of membrane proteins. Exploring their suitability for single particle X-ray diffraction will have a strong impact on X-FEL applications in Structural Biology, particular for the crystallization-independent structure determination of membrane proteins. Additionally, NDs will be labelled with small gold spheres of ~1.4nm diameter to aid particle identification and orientation. Sufficiently high concentrations of NDs have been obtained for preliminary X-ray diffraction experiments and aggregation can be prevented even at high concentrations (mg/ml).