Die strukturelle Grundlage der Signaltransduktion mit G-Protein-gekoppelten Rezeptoren (Nobel-Aufsatz)

Dynamics of Bacteriorhodopsin in the Dark-Adapted State from Solution Nuclear Magnetic Resonance Spectroscopy

To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR.

The Mutation in the Single-Crystal Structural Transformation Process, Induced by the Combined Stimuli of Temperature and Solvent

A 2D coordination polymer containing a free ligand (L_f ), fixed by hydrogen bonds, transformed into a 3D metal-organic framework (MOF) in a single-crystal to single-crystal fashion. This transformation occurs through the combined stimuli of temperature and solvent. From 50 to 90 °C, a series of changes take place in a gradual form: the L_f is slowly moved to the cobalt center, which is accompanied by a contraction of unit cell and hydrogen bond. When the temperature rises to 95 °C, the hydrogen bond is destroyed, and L_f is suddenly combined with the cobalt ion to form an intricate 3D structure. This mutation process is irreversible and cannot occur just with the stimulus of either temperature or solvent. Notably, even under the combined stimuli, this mutation phenomena is difficult to reproduce when the solvent species and proportions change. DFT calculations were used to try to explain the nature of the phenomenon.

Deoxycholate-Based Glycosides (DCGs) for Membrane Protein Stabilisation

Detergents are an absolute requirement for studying the structure of membrane proteins. However, many conventional detergents fail to stabilise denaturation-sensitive membrane proteins, such as eukaryotic proteins and membrane protein complexes. New amphipathic agents with enhanced efficacy in stabilising membrane proteins will be helpful in overcoming the barriers to studying membrane protein structures. We have prepared a number of deoxycholate-based amphiphiles with carbohydrate head groups, designated deoxycholate-based glycosides (DCGs). These DCGs are the hydrophilic variants of previously reported deoxycholate-based N-oxides (DCAOs). Membrane proteins in these agents, particularly the branched diglucoside-bearing amphiphiles DCG-1 and DCG-2, displayed favourable behaviour compared to previously reported parent compounds (DCAOs) and conventional detergents (LDAO and DDM). Given their excellent properties, these agents should have significant potential for membrane protein studies.

Structures of class B G protein-coupled receptors: prospects for drug discovery

New members in the GPCR photo gallery! Crystal structures of class B G protein-coupled receptors, which bind peptide hormones, have been solved [see picture of the corticotropin-releasing factor receptor 1 (blue) and a bound allosteric nonpeptide antagonist (green)]. The structures provide a basis for a rational design of better drugs for diabetes, osteoporosis, migraine, or depression.