Assisting and accelerating NMR assignment with restrained structure prediction.

Accurate dynamic protein structures are essential for drug design. NMR experiments can detect protein structures and potential dynamics, but the spectrum assignment and structure determination requires expertise and is time-consuming, while deep-learning-based structure predictions may be inconsistent with experimental observations. A symbiosis between experiments and AI methods is therefore essential for solving such problems.

Structural Mechanism of Insect Cuticular Protein Binding to Chitin Revealed by Solid-State NMR.

The exoskeleton of an insect is a fascinating example of how nature employs organic substances to craft high-performance materials, characterized by their hardness, tensile strength, and lightweight. Dissecting the atomic-level arrangement of these multifunctional organics, primarily proteins and chitin, within insect cuticles will aid in deciphering this enigma. Despite its importance, revealing the mechanism of interaction between cuticular proteins and chitin polysaccharides in heterogeneous systems remains a challenge.

Solution NMR Analysis Reveals Synergistic β-Arrestin1 Activation by Chemically Synthesized Phosphopeptides of a C-Terminal Tail and ICL3 of NTSR1.

β-Arrestins are critical regulators of G-protein-coupled receptors (GPCRs), mediating desensitization, internalization, and activation of alternative downstream signal transduction pathways through selective binding to phosphorylated GPCRs. Although phosphorylation of C-terminal tails (C-tail) and intracellular loop 3 (ICL3) of GPCRs is essential for β-arrestin binding to GPCRs, cooperative interactions of the phosphorylated C-tail or ICL3 of GPCRs for β-arrestin recruitment remain elusive. Here, we chemically synthesized phosphorylated C-tail and ICL3 peptides of neurotensin receptor 1 (NTSR1) and investigated the conformational dynamics of β-arrestin1 during its interaction with the phosphopeptides.

Somatostatin receptor 2 targeting peptide modifications for peptide-drug conjugate treatment of small cell lung cancer.

Peptide-drug conjugate (PDC) represents a special therapeutic strategy to enhance drug delivery by targeting tumor cell receptors while minimizing off-target effects. Comparing the antibody-drug conjugate (ADC), the targeting peptide constitutes the pivotal component of PDC, especially with easy optimization of peptides to promote their in vivo stability, and with the agonist stimulated GPCR internalization to facilitate drug distribution into tumor cell plasma. Herein, we have optimized a highly stable peptide molecule LanTC targeting somatostatin receptor 2 (SSTR2), through amino acid substitution and disulfide bond modification from an FDA proved peptide drug Lanreotide.

Electron Paramagnetic Resonance Insights into Direct Electron Transfer Between FDX1 and Elesclomol-Cu Complex in Cuproptosis.

Copper-induced cell death, known as cuproptosis, is distinct from other forms of cell death processes. Previous studies have proposed Elesclomol (ES) as a potent cuproptosis inducer, with the mitochondrial ferredoxin protein FDX1 postulated as its primary target. However, the mechanistic details of electron transfer (ET) between Elesclomol-Cu (ES-Cu) and FDX1 remain elusive, particularly lacking direct spectroscopic evidence.

Structural basis for allosteric agonism of human α7 nicotinic acetylcholine receptors.

The α7 nicotinic acetylcholine receptor (nAChR), a pentameric ligand-gated ion channel, plays important roles in cognition, neuroprotection, and anti-inflammation. As a potential drug target, α7 nAChR has different binding sites for different ligands, particularly agonists and positive allosteric modulators (PAMs). Ago-PAMs can both directly activate and allosterically modulate α7 nAChR.

F NMR chemical shift encoded peptide screening targeting the potassium channel Kv1.3.

F nuclear magnetic resonance (F-NMR) is a pivotal technique for protein dynamic studies and drug screening because of its high sensitivity. Herein, we report a F-NMR chemical shift-based ligand screening strategy targeting membrane proteins using multiple peptide ligands containing different F-incorporating unnatural amino acids. Five different F-labelled unnatural amino acids (F, F, W, W and W) with distinctive F chemical shift values were applied to chemically synthesize multiple toxin peptides, which can potentially bind to and inhibit the conductance function of the autoimmune disease-related potassium channel Kv1.

Molecular mechanism of the arrestin-biased agonism of neurotensin receptor 1 by an intracellular allosteric modulator.

Biased allosteric modulators (BAMs) of G protein-coupled receptors (GPCRs) have been at the forefront of drug discovery owing to their potential to selectively stimulate therapeutically relevant signaling and avoid on-target side effects. Although structures of GPCRs in complex with G protein or GRK in a BAM-bound state have recently been resolved, revealing that BAM can induce biased signaling by directly modulating interactions between GPCRs and these two transducers, no BAM-bound GPCR-arrestin complex structure has yet been determined, limiting our understanding of the full pharmacological profile of BAMs. Herein, we developed a chemical protein synthesis strategy to generate neurotensin receptor 1 (NTSR1) with defined hexa-phosphorylation at its C-terminus and resolved high-resolution cryo-EM structures (2.

Plant essential oil targets TRPV3 for skin renewal and structural mechanism of action.

Our skin safeguards the body homeostasis for health and also provides psychological consolation in social life. Natural essential oils are widely used for skin maintenance, while the molecular target and mechanism of action remain largely unknown. Here, we report that citronellal, a plant-derived acyclic monoterpene commonly used for personal care, stimulates skin renewal by promoting keratinocyte proliferation through the activation of TRPV3.

Optimizing Peptide-Conjugated Lipid Nanoparticles for Efficient siRNA Delivery across the Blood-Brain Barrier and Treatment of Glioblastoma Multiforme.

Glioblastoma multiforme (GBM) is a WHO grade 4 glioma and the most common malignant primary brain tumor. Addressing the clinical management of GBM presents an exceptionally daunting and intricate challenge, particularly in overcoming the blood-brain barrier (BBB) to deliver effective therapies to the brain. Nanotechnology-based drug delivery systems have exhibited considerable promise in tackling this aggressive brain cancer.

Chiral Nanostructured Ag Films for Multicarbon Products from CO Electroreduction.

The formation of multicarbon products from CO electroreduction is challenging on materials other than Cu-based catalysts. Ag has been known to be a typical metal catalyst, producing CO in CO electroreduction. The formation of C products by Ag has never been reported because the carbon-carbon (C-C) coupling is an unfavorable process due to the high reaction barrier energy of *OCCO.

Electron spin resonance analysis of photoenzymatic catalysis.

This Perspective highlights recent research progress and prospects in elucidating the catalytic mechanism of photoenzymes using ESR (electron spin resonance) spectroscopy, which is emerging as a unique and crucial method for identifying radical intermediates, illustrating electron transfer events and the underlying mechanisms of photoenzymatic catalysis.

Efficient Chemical Synthesis of Multi-Monoubiquitylated and Diubiquitylated Histones by the α-Halogen Ketone-Mediated Strategy.

The chemical synthesis of homogeneously ubiquitylated histones is a powerful approach to decipher histone ubiquitylation-dependent epigenetic regulation. Among the various methods, α-halogen ketone-mediated conjugation chemistry has recently been an attractive strategy to generate single-monoubiquitylated histones for biochemical and structural studies. Herein, we report the use of this strategy to prepare not only dual- and even triple-monoubiquitylated histones but also diubiquitin-modified histones.

Structural insights into somatostatin receptor 5 bound with cyclic peptides.

Somatostatin receptor 5 (SSTR5) is highly expressed in ACTH-secreting pituitary adenomas and is an important drug target for the treatment of Cushing's disease. Two cyclic SST analog peptides (pasireotide and octreotide) both can activate SSTR5 and SSTR2. Pasireotide is preferential binding to SSTR5 than octreotide, while octreotide is biased to SSTR2 than SSTR5.

Imaging and quantification of neuropeptides in mouse pituitary tissue by atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry.

Rationale: Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) mass spectrometry has enabled the untargeted analysis and imaging of neuropeptides and proteins in biological tissues under ambient conditions. Sensitivity in AP-MALDI can be improved by using sample-specific preparation methods.

Methods: A comprehensive and detailed optimization strategy including instrument parameters, matrix spraying and sample tissue washing pretreatment was implemented to enhance the sensitivity and coverage of neuropeptides in mouse pituitary tissues by commercial AP-MALDI mass spectrometry imaging (MSI).

Development of Transmission Ambient Pressure Laser Desorption Ionization/Postphotoionization Mass Spectrometry Imaging.

Laser-based high-resolution mass spectrometry imaging at ambient conditions has promising applications in life science. However, the ion yield during laser desorption/ablation is poor. Here, transmission atmospheric pressure laser desorption ionization combined with a compact postphotoionization (t-AP-LDI/PI) assembly with a krypton discharge lamp was developed for the untargeted imaging of various biomolecules.

De Novo Screening and Mirror Image Isomerization of Linear Peptides Targeting α7 Nicotinic Acetylcholine Receptor.

As ligand-gated ion channels, nicotinic acetylcholine receptors (nAChRs) are widely distributed in the central and peripheral nervous systems and are associated with the pathogenesis of various degenerative neurological diseases. Here, we report the results of phage display-based de novo screening of an 11-residue linear peptide (named KP1794) that targets the α7 nAChR, which is among the most abundant nAChR subtypes in the brain. Moreover, two d-peptides were generated through mirror image and/or primary sequence inverso isomerization (termed KP1794 and KP1794) and displayed improved inhibitory effects (IC = 0.

Peptide Stapling by Crosslinking Two Amines with α-Ketoaldehydes through Diverse Modified Glyoxal-Lysine Dimer Linkers.

α-Ketoaldehydes play versatile roles in the ubiquitous natural processes of protein glycation. However, leveraging the reactivity of α-ketoaldehydes for biomedical applications has been challenging. Previously, the reactivity of α-ketoaldehydes with guanidine has been harnessed to design probes for labeling Arg residues on proteins in an aqueous medium.

Cryo-EM structure of HQNO-bound alternative complex III from the anoxygenic phototrophic bacterium Chloroflexus aurantiacus.

Alternative complex III (ACIII) couples quinol oxidation and electron acceptor reduction with potential transmembrane proton translocation. It is compositionally and structurally different from the cytochrome bc1/b6f complexes but functionally replaces these enzymes in the photosynthetic and/or respiratory electron transport chains (ETCs) of many bacteria. However, the true compositions and architectures of ACIIIs remain unclear, as do their structural and functional relevance in mediating the ETCs.

A light-driven enzymatic enantioselective radical acylation.

Enzymes are recognized as exceptional catalysts for achieving high stereoselectivities, but their ability to control the reactivity and stereoinduction of free radicals lags behind that of chemical catalysts. Thiamine diphosphate (ThDP)-dependent enzymes are well-characterized systems that inspired the development of N-heterocyclic carbenes (NHCs) but have not yet been proved viable in asymmetric radical transformations. There is a lack of a biocompatible and general radical-generation mechanism, as nature prefers to avoid radicals that may be harmful to biological systems.

In vivo labeling and quantitative imaging of neuronal populations using MRI.

The study of neural circuits, which underlies perception, cognition, emotion, and behavior, is essential for understanding the mammalian brain, a complex organ consisting of billions of neurons. To study the structure and function of the brain, in vivo neuronal labeling and imaging techniques are crucial as they provide true physiological information that ex vivo methods cannot offer. In this paper, we present a new strategy for in vivo neuronal labeling and quantification using MRI.

A cytochrome c mediates the cyclic electron transport chain of the anoxygenic phototrophic bacterium Roseiflexus castenholzii.

Roseiflexus castenholzii is a gram-negative filamentous phototrophic bacterium that carries out anoxygenic photosynthesis through a cyclic electron transport chain (ETC). The ETC is composed of a reaction center (RC)-light-harvesting (LH) complex (rcRC-LH); an alternative complex III (rcACIII), which functionally replaces the cytochrome bc/bf complex; and the periplasmic electron acceptor auracyanin (rcAc). Although compositionally and structurally different from the bc/bf complex, rcACIII plays similar essential roles in oxidizing menaquinol and transferring electrons to the rcAc.