Volume 22 Issue 10, October 2015

The crystal structure of a prokaryotic proton-driven fumarate transporter, the first for the diverse SLC26 transporter family, reveals a rare transmembrane-segment topology. The opposite orientation of two short central helices leads to the formation of a dipole-mediated anion-binding site, which is made alternately accessible to either side of the membrane through the rocking movement of the core and gate domains of the transporter.

The cellular 'alarmone' molecule ZTP accumulates when a critical cellular metabolic pathway is starved for substrate. The high-resolution structure of ZTP bound to its RNA-based sensor reveals unexpected strategies used by RNA to specifically recognize small-molecule ligands within the complex cellular mixture.

How is cellular cargo delivered at the right time and the right place, in response to the right signal? A key new piece in this fascinating biological puzzle has just been revealed.

New data show that Clock–Bmal1, the central transcriptional activator that drives expression of circadian target genes, also recruits the Ddb1–Cullin-4 ubiquitin ligase to clock promoters to enhance the subsequent binding of the feedback repressors that generate the circadian periodicity of gene expression.

Cryo-EM analysis of a bacterial SRP reveals that, differently from eukaryotic SRP, it interacts with the ribosome via contacts between the 6S RNA and the 23S rRNA to mediate translational slowdown.

An in vitro–reconstitution approach reveals the interactions between nuclear pore complex modules. Short motifs within linker nucleoporins connect the inner-pore-ring complex with subcomplexes of the outer ring and the transport channel.

Crystallographic and cryo-EM analyses using short synthetic single-stranded RNAs unveil the structural basis for recognition of bacterial 23S rRNA and vesicular stomatitis virus by Toll-like receptor 13, which triggers an immune response.

Foot-and-mouth disease virus (FMDV) capsids are often unstable, thus limiting their use as vaccines. A computational method was used to strengthen protein-protein interfaces and engineer stabilized FMDV capsids, which generated improved antibody responses in vaccinated calves and guinea pigs.

AFM and NMR are used to observe how the chaperones Skp and SurA work to fold a β-barrel outer-membrane protein, FhuA. Skp maintains FhuA in an unfolded state, and Sur A facilitates its folding.

SLC26 membrane proteins constitute a large family of anion transporters with diverse functions. The first structure of a full-length SLC26 transporter now provides a common framework for the architecture of this protein family.

Solution NMR and functional analyses reveal the 3D structure of a transmembrane reductase, the archeal CcdA, and suggest a mechanism for how these enzymes relay electrons across cell membranes.

Concentrations of cations and ATP affect the binding activities of synaptotagmin-1, to trigger synaptic vesicle exocytosis. In physiological ionic conditions, synaptotagmin-1's interaction with SNARE proteins is prevented, and its binding is confined to PIP₂-containing membrane.

In somatic cells, L1 retrotransposition is kept in check by DNA methylation. However, in hypomethylated cells, such as cancer cells or iPSCs, miR-128 represses new retrotransposition events and thus might aid in maintaining genome stability.