Local frustration determines loop opening during the catalytic cycle of an oxidoreductase.

Local structural frustration, the existence of mutually exclusive competing interactions, may explain why some proteins are dynamic while others are rigid. Frustration is thought to underpin biomolecular recognition and the flexibility of protein-binding sites. Here, we show how a small chemical modification, the oxidation of two cysteine thiols to a disulfide bond, during the catalytic cycle of the N-terminal domain of the key bacterial oxidoreductase DsbD (nDsbD), introduces frustration ultimately influencing protein function.

Cryo-EM structure of the mechanically activated ion channel OSCA1.2.

Mechanically activated ion channels underlie touch, hearing, shear-stress sensing, and response to turgor pressure. OSCA/TMEM63s are a newly-identified family of eukaryotic mechanically activated ion channels opened by membrane tension. The structural underpinnings of OSCA/TMEM63 function are not explored.

Proton currents constrain structural models of voltage sensor activation.

The Hv1 proton channel is evidently unique among voltage sensor domain proteins in mediating an intrinsic 'aqueous' H conductance (G). Mutation of a highly conserved 'gating charge' residue in the S4 helix (R1H) confers a resting-state H 'shuttle' conductance (G) in VGCs and Ci VSP, and we now report that R1H is sufficient to reconstitute G in Hv1 without abrogating G. Second-site mutations in S3 (D185A/H) and S4 (N4R) experimentally separate G and G gating, which report thermodynamically distinct initial and final steps, respectively, in the Hv1 activation pathway.

Molecular dynamics simulations of membrane proteins and their interactions: from nanoscale to mesoscale.

Molecular dynamics simulations provide a computational tool to probe membrane proteins and systems at length scales ranging from nanometers to close to a micrometer, and on microsecond timescales. All atom and coarse-grained simulations may be used to explore in detail the interactions of membrane proteins and specific lipids, yielding predictions of lipid binding sites in good agreement with available structural data. Building on the success of protein-lipid interaction simulations, larger scale simulations reveal crowding and clustering of proteins, resulting in slow and anomalous diffusional dynamics, within realistic models of cell membranes.

Insights into the structural nature of the transition state in the Kir channel gating pathway.

In a previous study we identified an extensive gating network within the inwardly rectifying Kir1.1 (ROMK) channel by combining systematic scanning mutagenesis and functional analysis with structural models of the channel in the closed, pre-open and open states. This extensive network appeared to stabilize the open and pre-open states, but the network fragmented upon channel closure.