- Osmotic fitness in Pseudomonas aeruginosa
Pseudomonas aeruginosa is resistant to drastic osmotic changes because of its ability to quickly jettison small osmolytes through osmotic release channels. Çetiner et al. reveal that it uses one MscL-like and at least two types of MscS-like channels during its osmotic response.
- Isoflurane modulates NaChBac gating
The pharmacological effects of inhaled anesthetics on ion channel function are poorly understood. Sand et al. analyze macroscopic gating of the prokaryotic voltage-gated sodium channel, NaChBac, using a six-state kinetic scheme and demonstrate that isoflurane modulates microscopic gating properties.
- Identifiability, reducibility, and adaptability
Bohner and Venkataraman propose a link between the sensitivity of allosteric macromolecules to their underlying biophysical parameters, the interrelationships between these parameters, and macromolecular adaptability. They argue that “emergent” combinations of parameters yield mechanistic insight that individual parameters cannot.
- Mechanism of Kir channel inactivation
The pore-forming unit of ATP-sensitive K channels is composed of four Kir6.2 subunits. Borschel et al. show that salt bridges between the cytoplasmic domain of adjacent Kir6.2 subunits determine the degree to which channels inactivate after removal of ATP.
- Sodium channel block
A number of different drugs block sodium channels, but their mechanism of block is unclear. Tikhonov and Zhorov combine homology modeling with ligand docking and propose a pharmacophore for sodium channel blockers involving cationic and aromatic moieties.
- Monobody block of dual topology fluoride channels
Fibronectin domain monobodies bind to both sides of Fluc Fl− channels in a negatively cooperative way, but crystal structures show two monobodies binding simultaneously. Turman and Stockbridge resolve this contradiction by showing that monobodies block channel pores by means of a negatively charged loop.
- The Trichoplax adhaerens T-type calcium channel
The role of T-type calcium channels in animals without nervous systems is unknown. Smith et al. characterize TCav3 from Trichoplax adhaerens, finding expression in neurosecretory-like cells and preference for Ca2+ over Na+ via strong extracellular Ca2+ block, despite low selectivity for Ca2+ in the pore.