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Characterization of dynamic conformational changes in membrane protein complexes by NMR spectroscopy remains challenging. Here authors report the site-specific incorporation of 4-trimethylsilyl phenylalanine (TMSiPhe) into proteins, which enabled the characterization of multiple conformational states of a phospho-β2 adrenergic receptor/β-arrestin-1 complex in response to different receptor ligands.

Abstract Hydrogen production from seawater remains challenging due to the deactivation of the hydrogen evolution reaction (HER) electrode under high current density. To overcome the activity-stability trade-offs in transition-metal sulfides, we propose a strategy to engineer sulfur migration by constructing a nickel-cobalt sulfides heterostructure with nitrogen-doped carbon shell encapsulation (CN@NiCoS) electrocatalyst. State-of-the-art ex situ/in situ characterizations and density functional theory calculations reveal the restructuring of the CN@NiCoS interface, clearly identifying dynamic sulfur migration. The NiCoS heterostructure stimulates sulfur migration by creating sulfur vacancies at the Ni3S2-Co9S8 heterointerface, while the migrated sulfur atoms are subsequently captured by the CN shell via strong C-S bond, preventing sulfide dissolution into alkaline electrolyte. Remarkably, the dynamically formed sulfur-doped CN shell and sulfur vacancies pairing sites significantly enhances HER activity by altering the d-band center near Fermi level, resulting in a low overpotential of 4.6 and 8 mV at 10 mA cm−2 in alkaline freshwater and seawater media, and long-term stability up to 1000 h. This work thus provides a guidance for the design of high-performance HER electrocatalyst by engineering interfacial atomic migration.

Abstract Chloride channels (CLCs) transport anion across membrane to regulate ion homeostasis and acidification of intracellular organelles, and are divided into anion channels and anion/proton antiporters. Arabidopsis thaliana CLCa (AtCLCa) transporter localizes to the tonoplast which imports NO3 − and to a less extent Cl− from cytoplasm. The activity of AtCLCa and many other CLCs is regulated by nucleotides and phospholipids, however, the molecular mechanism remains unclear. Here we determine the cryo-EM structures of AtCLCa bound with NO3 − and Cl−, respectively. Both structures are captured in ATP and PI(4,5)P2 bound conformation. Structural and electrophysiological analyses reveal a previously unidentified N-terminal β-hairpin that is stabilized by ATP binding to block the anion transport pathway, thereby inhibiting the AtCLCa activity. While AMP loses the inhibition capacity due to lack of the β/γ- phosphates required for β-hairpin stabilization. This well explains how AtCLCa senses the ATP/AMP status to regulate the physiological nitrogen-carbon balance. Our data further show that PI(4,5)P2 or PI(3,5)P2 binds to the AtCLCa dimer interface and occupies the proton-exit pathway, which may help to understand the inhibition of AtCLCa by phospholipids to facilitate guard cell vacuole acidification and stomatal closure. In a word, our work suggests the regulatory mechanism of AtCLCa by nucleotides and phospholipids under certain physiological scenarios and provides new insights for future study of CLCs.

The current use of elastography ultrasound faces challenges, including vulnerability to subjective manipulation, echo signal attenuation, unknown risks of elastic pressure and high imaging hardware cost. Here, the author shows a virtual elastography to empower low-end ultrasound devices with state-of-art elastography function.

In this work, the authors report Cryo-EM structures of the signaling complexes of human GPR21, an orphan GPCR and a potential metabolic disease target, and reveal unique receptor activation conformation when bound to downstream signaling proteins in the absence of any ligand.

G protein-coupled receptors (GPCRs) are a critical target in modern drug development across a wide range of indications. Here the authors provide a comprehensive characterization of a typical GPCR, the angiotensin II (AngII) type 1 receptor (AT1R), and provide insight into its activation mechanism that suggest avenues for the design of allosteric GPCR modulators.

Breast cancer is frequently diagnosed using ultrasound. Here, the authors show that, in addition to ultrasound, shear wave elastography can be used to diagnose breast cancer and, in conjunction with deep learning and radiomics, can predict whether the disease has spread to axillary lymph nodes.

On-site diagnostics technologies allow for rapid, cost-effective diagnosis with a particular importance for remote communities. Here the authors demonstrate the use of mobile phone based microscopy for targeted DNA sequencing andin situpoint mutation detection in tumours.

Pentatricopeptide repeat (PPR) proteins bind RNA and are involved in the regulation of RNA metabolism in eukaryotes. Here, the authors examine the capability of these proteins as modules for gene manipulation using structural biology methods.

Characterization of the dynamic conformational changes in membrane protein signaling complexes by nuclear magnetic resonance (NMR) spectroscopy remains challenging. Here we report the site-specific incorporation of 4-trimethylsilyl phenylalanine (TMSiPhe) into proteins, through genetic code expansion. Crystallographic analysis revealed structural changes that reshaped the TMSiPhe-specific amino-acyl tRNA synthetase active site to selectively accommodate the trimethylsilyl (TMSi) group. The unique up-field 1H-NMR chemical shift and the highly efficient incorporation of TMSiPhe enabled the characterization of multiple conformational states of a phospho-β2 adrenergic receptor/β-arrestin-1(β-arr1) membrane protein signaling complex, using only 5 μM protein and 20 min of spectrum accumulation time. We further showed that extracellular ligands induced conformational changes located in the polar core or ERK interaction site of β-arr1 via direct receptor transmembrane core interactions. These observations provided direct delineation and key mechanism insights that multiple receptor ligands were able to induce distinct functionally relevant conformational changes of arrestin. Characterization of dynamic conformational changes in membrane protein complexes by NMR spectroscopy remains challenging. Here authors report the site-specific incorporation of 4-trimethylsilyl phenylalanine (TMSiPhe) into proteins, which enabled the characterization of multiple conformational states of a phospho-β2 adrenergic receptor/β-arrestin-1 complex in response to different receptor ligands. [ABSTRACT FROM AUTHOR]