Membrane protein structure determination by electron crystallography

Abstract

During the past year, electron crystallography of membrane proteins has provided structural insights into the mechanism of several different transporters and into their interactions with lipid molecules within the bilayer. From a technical perspective there have been important advances in high-throughput screening of crystallization trials and in automated imaging of membrane crystals with the electron microscope. There have also been key developments in software, and in molecular replacement and phase extension methods designed to facilitate the process of structure determination.

Membrane protein structural biology using X-ray free electron lasers

“…This arrangement is closer to physiological conditions than a 3D crystal and provides accessibility to both sides of the protein for ligand interaction. Due to their small size, 2D-crystals suffer from severe radiation damage at synchrotrons and have therefore previously been examined using electron diffraction at cryogenic temperatures [58][59][60]. The main bottlenecks so far are technical difficulties in preparing well ordered 2D crystals, missing possibilities for correcting for lattice bending through image processing, the missing cone problem when collecting tilted data [61] and a lack of automation for 2D crystal production.…”

Monolayer-to-thin-film transition in supramolecular assemblies: the role of topological protection

“…On the other hand, analysis in the TEM through combined diffraction and imaging experiments has in principle the potential to resolve organic structures with sub-molecular resolution. 29 , 30 Recent technical advances in TEM, such as aberration correction for sub-angstrom resolution imaging and single electron detection cameras for low noise acquisition, are opening up new possibilities for studying molecular systems at even higher resolution. 31 For TEM, graphene is a particularly exciting and relevant substrate as it is almost perfectly electron transparent, conductive, crystalline, strong, and stable.…”

Structure of an E. coli integral membrane sulfurtransferase and its structural transition upon SCN− binding defined by EPR-based hybrid method

“…Structural studies of membrane proteins provide a detailed understanding of their functional mechanisms. X-ray diffraction and cryo-electron microscopy determine membrane protein structures at high resolution, whereas magnetic resonance methods can provide both structure and dynamic information for membrane proteins 1 2 . However, nuclear magnetic resonance (NMR) is only capable of characterizing small size membrane proteins, which has limited its application considerably.…”