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The diamide insecticide class is one of the top-selling insecticides globally. They are used to control a wide range of pests by targeting their ryanodine receptors (RyRs). Here, we report the highest-resolution cryo-electron microscopy (cryo-EM) structure of RyR1 in the open state, in complex with the anthranilic diamide chlorantraniliprole (CHL). The 3.2-Å local resolution map facilitates unambiguous assignment of the CHL binding site. The molecule induces a conformational change by affecting the S4–S5 linker, triggering channel opening. The binding site is further corroborated by mutagenesis data, which reveal how diamide insecticides are selective to the Lepidoptera group of insects over honeybee or mammalian RyRs. Our data reveal that several pests have developed resistance via two mechanisms, steric hindrance and loss of contact. Our results provide a foundation for the development of highly selective pesticides aimed at overcoming resistance and therapeutic molecules to treat human myopathies. Cryo-EM structural work defines binding of the insecticide CHL in the pseudo-voltage-sensor domain of ryanodine receptor RyR that triggers conformational changes leading to channel opening and explains the resistance to CHL by some insects.

Bacterial degradation of organosulfonates plays an important role in sulfur recycling, and has been extensively studied. However, this process in anaerobic bacteria especially gut bacteria is little known despite of its potential significant impact on human health with the production of toxic H 2 S. Here, we describe the structural and biochemical characterization of an oxygen-sensitive enzyme that catalyzes the radical-mediated C-S bond cleavage of isethionate to form sulfite and acetaldehyde. We demonstrate its involvement in pathways that enables C2 sulfonates to be used as terminal electron acceptors for anaerobic respiration in sulfate- and sulfite-reducing bacteria. Furthermore, it plays a key role in converting bile salt-derived taurine into H 2 S in the disease-associated gut bacterium Bilophila wadsworthia . The enzymes and transporters in these anaerobic pathways expand our understanding of microbial sulfur metabolism, and help deciphering the complex web of microbial pathways involved in the transformation of sulfur compounds in the gut. The C2 sulfonates taurine and isethionate are also present in the anaerobic mammalian gut, where they are converted into toxic H 2 S by sulfate and sulfite-reducing bacteria. Here the authors characterise the O 2 -sensitive enzyme IseG that catalyzes the C-S bond cleavage of isethionate and show that IseG also plays a key role in converting taurine into H 2 S in Bilophila wadsworthia .

The resistance of pests to common insecticides is a global issue that threatens food production worldwide. Diamide insecticides target insect ryanodine receptors (RyRs), causing uncontrolled calcium release from the sarcoplasmic and endoplasmic reticulum. Despite their high potency and species selectivity, several resistance mutations have emerged. Using a chimeric RyR (chiRyR) approach and cryo-electron microscopy (cryo-EM), we investigate how insect RyRs engage two different diamide insecticides from separate families: flubendiamide, a phthalic acid derivative, and tetraniliprole, an anthranilic compound. Both compounds target the same site in the transmembrane region of the RyR, albeit with different poses, and promote channel opening through coupling with the pore-forming domain. To explore the resistance mechanisms, we also solve two cryo-EM structures of chiRyR carrying the two most common resistance mutations, I4790M and G4946E, both alone and in complex with the diamide insecticide chlorantraniliprole. The resistance mutations perturb the local structure, directly reducing the binding affinity and altering the binding pose. Our findings elucidate the mode of action of different diamide insecticides, reveal the molecular mechanism of resistance mutations, and provide important clues for the development of novel pesticides that can bypass the resistance mutations. Pesticide resistance poses a serious threat to global food security. In this study, the authors show the mode of action of various diamide insecticides and elucidate the molecular mechanisms underlying resistance mutations.

Idiopathic ventricular fibrillation (IVF) causes sudden death in young adult patients without structural or ischemic heart disease. Most IVF cases are sporadic and some patients present with short-coupled torsade de pointes, the genetics of which are poorly understood. A man who had a first syncope at the age of 35 presented with frequent short-coupled premature ventricular beats with bursts of polymorphic ventricular tachycardia and then died suddenly. By exome sequencing, we identified three rare variants: p.I784F in the SPRY1 of the ryanodine receptor 2 (RyR2), p.A96S in connexin 40 (Cx40), reported to affect electrical coupling and cardiac conduction, and a nonsense p.R244X in the cardiac-specific troponin I-interacting kinase (TNNI3K). We assessed intracellular Ca 2+ handling in WT and mutant human  RYR2 transfected HEK293 cells by fluorescent microscopy and an enhanced store overload-induced Ca 2+ release in response to cytosolic Ca 2+ was observed in RyR2-I784F cells. In addition, crystal structures and thermal melting temperatures revealed a conformational change in the I784F-SPRY1 domain compared to the WT-domain. The novel RyR2-I784F variant in SPRY1 domain causes a leaky channel under non-stress conditions. The presence of several variants affecting Ca 2+ handling and cardiac conduction suggests a possible oligogenic origin for the ectopies originating from Purkinje fibres.

Many voltage-gated sodium channel-targeting animal peptide toxins are renowned for their potency and selectivity against insects. Understanding why these toxins selectively target insect sodium channels over their mammalian counterparts is crucial for developing safer and more effective pest control agents. Here, we present the cryoelectron microscopy (cryo-EM) structures of the insect sodium channel Na v PaS bound to two naturally occurring insect-selective toxins, Av3 from the sea anemone and LqhαIT from the scorpion. Both toxins bind to the voltage-sensing domain 4 (VSD4) of Na v PaS and disrupt fast inactivation by stabilizing the S4 segment in a deactivated conformation. While Av3 engages a membrane-embedded site between VSD4 and pore domain 1 (PD1), LqhαIT binds to the classical neurotoxin site 3, illustrating distinct binding modes that converge on a shared mechanism of action. These structures reveal the molecular determinants of insect selectivity and highlight the molecular coevolution of toxin-channel interactions, as corroborated by electrophysiology and toxicity assays. Leveraging these insights, we apply AI-driven protein design tools to increase the insecticidal potency of LqhαIT, resulting in a variant with a remarkable doubling in efficacy, as we confirm by insecticidal bioassays. This study illuminates the diverse mechanisms of sodium channel modulation and provides a framework for the structure-guided, AI-driven design of toxin-based biopesticides. The authors reveal how two insect-selective animal peptide toxins engage distinct sites on an insect sodium channel to disrupt fast inactivation and leverage these structural insights to AI-design a more potent toxin for biopesticide development.

The ryanodine receptor (RyR) is a critical drug target, yet dantrolene (DAN) remains the only FDA-approved inhibitor, limited by hepatotoxicity and unsuitable for chronic use. To guide improved inhibitor development, we determine high-resolution crystal structures of the RyR Repeat12 (R12) domain bound to DAN, its analog azumolene (AZU), and adenine nucleotides (AMP-PCP or ADP). DAN/AZU and nucleotides bind cooperatively to a pseudosymmetric cleft, with key interactions involving Trp880 and Trp994. Binding induces a clamshell-like closure of the R12 domain. Isothermal titration calorimetry (ITC) reveals higher affinity in the presence of nucleotides and lower affinity for RyR2 due to nearby substitutions. Structural comparison with cryo-EM data suggests that DAN/AZU binding allosterically influences RyR gating and functional regulation. Structure-based screening identifies a potent compound targeting the same site but with a distinct binding mode. Our findings highlight the power of domain-focused crystallography in guiding RyR inhibitor discovery and overcoming cryo-EM resolution limitations. This study reports crystal structures of the ryanodine receptor domain bound to dantrolene and azumolene. The work reveals cooperative nucleotide binding and provides structural insights to guide the design of potent inhibitors targeting the receptor.

Several mutations identified in phospholamban (PLN) have been linked to familial dilated cardiomyopathy (DCM) and heart failure, yet the underlying molecular mechanism remains controversial. PLN interacts with sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA) and regulates calcium uptake, which is modulated by the protein kinase A (PKA)-dependent phosphorylation of PLN during the fight-or-flight response. Here, we present the crystal structures of the catalytic domain of mouse PKA in complex with wild-type and DCM-mutant PLNs. Our structures, combined with the results from other biophysical and biochemical assays, reveal a common disease mechanism: the mutations in PLN reduce its phosphorylation level by changing its conformation and weakening its interactions with PKA. In addition, we demonstrate that another more ubiquitous SERCA-regulatory peptide, called another-regulin (ALN), shares a similar mechanism mediated by PKA in regulating SERCA activity.

Experimental 3D structures of calcium channels with phenylalkylamines (PAAs) provide basis for further analysis of atomic mechanisms of these important cardiovascular drugs. In the crystal structure of the engineered calcium channel CavAb with Br-verapamil and in the cryo-EM structure of the Cav1.1 channel with verapamil, the ligands bind in the inner pore. However, there are significant differences between these structures. In the crystal structure the ligand ammonium group is much closer to the ion in the selectivity-filter region Site 3, which is most proximal to the inner pore, than in the cryo-EM structure. Here we used Monte Carlo energy minimizations to dock PAAs in calcium channels. Our computations suggest that in the crystal structure Site 3 is occupied by a water molecule rather than by a calcium ion. Analysis of the published electron density map does not rule out this possibility. In the cryo-EM structures the ammonium group of verapamil is shifted from the calcium ion in Site 3 either along the pore axis, towards the cytoplasm or away from the axis. Our unbiased docking reproduced these binding modes. However, in the cryo-EM structures detergent and lipid molecules interact with verapamil. When we removed these molecules, the nitrile group of verapamil bound to the calcium ion in Site 3. Models of Cav1.2 with different PAAs suggest similar binding modes and direct contacts of the ligands electronegative atoms with the calcium ion in Site 3. Such interactions explain paradoxes in structure–activity relationships of PAAs.

Protein Tyrosine Phosphatase 1B (PTP1B) is a key immune regulator in cancer and an attractive immunotherapy target, yet progress is limited by the lack of selective inhibitors. Here, we identify Fumosorinone (FU), a natural product from Isaria fumosorosea , as a potent and selective allosteric inhibitor of PTP1B. In a murine colon tumor model, FU enhances anti-tumor immunity by reshaping the microenvironment, strengthening CD8⁺ T-cell responses, and promoting M1-like macrophage polarization. Enzymatic and biophysical analyses confirm its potency and direct engagement with PTP1B. A co-crystal structure defines a previously uncharacterized allosteric pocket that stabilizes the inactive state of the enzyme. This pocket is poorly conserved across the PTP family, consistent with minimal activity toward related phosphatases except TCPTP. Guided by this insight, virtual screening identifies additional inhibitors. These findings provide a structural basis for selective PTP1B targeting and support future immunotherapy development and rational drug discovery efforts. This study defines a previously uncharacterized allosteric pocket in Protein Tyrosine Phosphatase 1B that locks the enzyme in an inactive state, enabling selective inhibition and structure-guided immunotherapy design.