Real time dynamics of Gating-Related conformational changes in CorA.

CorA, a divalent-selective channel in the metal ion transport superfamily, is the major Mg-influx pathway in prokaryotes. CorA structures in closed (Mg-bound), and open (Mg-free) states, together with functional data showed that Mg-influx inhibits further Mg-uptake completing a regulatory feedback loop. While the closed state structure is a symmetric pentamer, the open state displayed unexpected asymmetric architectures.

Crystal structure and dynamics of a lipid-induced potential desensitized-state of a pentameric ligand-gated channel.

Desensitization in pentameric ligand-gated ion channels plays an important role in regulating neuronal excitability. Here, we show that docosahexaenoic acid (DHA), a key ω-3 polyunsaturated fatty acid in synaptic membranes, enhances the agonist-induced transition to the desensitized state in the prokaryotic channel GLIC. We determined a 3.

A chimeric prokaryotic pentameric ligand-gated channel reveals distinct pathways of activation.

Recent high resolution structures of several pentameric ligand-gated ion channels have provided unprecedented details of their molecular architecture. However, the conformational dynamics and structural rearrangements that underlie gating and allosteric modulation remain poorly understood. We used a combination of electrophysiology, double electron-electron resonance (DEER) spectroscopy, and x-ray crystallography to investigate activation mechanisms in a novel functional chimera with the extracellular domain (ECD) of amine-gated Erwinia chrysanthemi ligand-gated ion channel, which is activated by primary amines, and the transmembrane domain of Gloeobacter violaceus ligand-gated ion channel, which is activated by protons.

Stochastic-shielding approximation of Markov chains and its application to efficiently simulate random ion-channel gating.

Markov chains provide realistic models of numerous stochastic processes in nature. We demonstrate that in any Markov chain, the change in occupation number in state A is correlated to the change in occupation number in state B if and only if A and B are directly connected. This implies that if we are only interested in state A, fluctuations in B may be replaced with their mean if state B is not directly connected to A, which shortens computing time considerably.

AFM and STM characterization of thiol and thiophene functionalized SWNTs: pitfalls in the use of chemical markers to determine the extent of sidewall functionalization in SWNTs.

Thiol- and thiophene-functionalized SWNTs prepared via the reaction of a substituted amine with fluoronanotubes show similar levels of sidewall functionalization, however, the use of Au nanoparticles as chemical markers for AFM gives misleading results for substituent distribution since STM shows the thiol substituents grouped in bands while the thiophene substituents uniformly distributed along the SWNTs.