Immunomimetic Designer Cells Protect Mice from MRSA Infection.

Many community- and hospital-acquired bacterial infections are caused by antibiotic-resistant pathogens. Methicillin-resistant Staphylococcus aureus (MRSA) predisposes humans to invasive infections that are difficult to eradicate. We designed a closed-loop gene network programming mammalian cells to autonomously detect and eliminate bacterial infections. The genetic circuit contains human Toll-like receptors as the bacterial sensor and a synthetic promoter driving reversible and adjustable expression of lysostaphin, a bacteriolytic enzyme highly lethal to S. aureus. Immunomimetic designer cells harboring this genetic circuit exhibited fast and robust sense-and-destroy kinetics against live staphylococci. When tested in a foreign-body infection model in mice, microencapsulated cell implants prevented planktonic MRSA infection and reduced MRSA biofilm formation by 91%. Notably, this system achieved a 100% cure rate of acute MRSA infections, whereas conventional vancomycin treatment failed. These results suggest that immunomimetic designer cells could offer a therapeutic approach for early detection, prevention, and cure of pathogenic infections in the post-antibiotic era.

Point mutation in a virus-like capsid drives symmetry reduction to form tetrahedral cages.

Protein capsids are a widespread form of compartmentalization in nature. Icosahedral symmetry is ubiquitous in capsids derived from spherical viruses, as this geometry maximizes the internal volume that can be enclosed within. Despite the strong preference for icosahedral symmetry, we show that simple point mutations in a virus-like capsid can drive the assembly of unique symmetry-reduced structures. Starting with the encapsulin from Myxococcus xanthus, a 180-mer bacterial capsid that adopts the well-studied viral HK97 fold, we use mass photometry and native charge detection mass spectrometry to identify a triple histidine point mutant that forms smaller dimorphic assemblies. Using cryoelectron microscopy, we determine the structures of a precedented 60-mer icosahedral assembly and an unexpected 36-mer tetrahedron that features significant geometric rearrangements around a new interaction surface between capsid protomers. We subsequently find that the tetrahedral assembly can be generated by triple-point mutation to various amino acids and that even a single histidine point mutation is sufficient to form tetrahedra. These findings represent a unique example of tetrahedral geometry when surveying all characterized encapsulins, HK97-like capsids, or indeed any virus-derived capsids reported in the Protein Data Bank, revealing the surprising plasticity of capsid self-assembly that can be accessed through minimal changes in the protein sequence.

An interaction network approach predicts protein cage architectures in bionanotechnology.

Protein nanoparticles play pivotal roles in many areas of bionanotechnology, including drug delivery, vaccination, and diagnostics. These technologies require control over the distinct particle morphologies that protein nanocontainers can adopt during self-assembly from their constituent protein components. The geometric construction principle of virus-derived protein cages is by now fairly well understood by analogy to viral protein shells in terms of Caspar and Klug's quasi-equivalence principle. However, many artificial, or genetically modified, protein containers exhibit varying degrees of quasi-equivalence in the interactions between identical protein subunits. They can also contain a subset of protein subunits that do not participate in interactions with other assembly units, called capsomers, leading to gaps in the particle surface. We introduce a method that exploits information on the local interactions between the capsomers to infer the geometric construction principle of these nanoparticle architectures. The predictive power of this approach is demonstrated here for a prominent system in nanotechnology, the AaLS pentamer. Our method not only rationalises hitherto discovered cage structures but also predicts geometrically viable options that have not yet been observed. The classification of nanoparticle architecture based on the geometric properties of the interaction network closes a gap in our current understanding of protein container structure and can be widely applied in protein nanotechnology, paving the way to programmable control over particle polymorphism.

Dual effector population modification gene-drive strains of the African malaria mosquitoes, Anopheles gambiae and Anopheles coluzzii.

Proposed genetic approaches for reducing human malaria include population modification, which introduces genes into vector mosquitoes to reduce or prevent parasite transmission. We demonstrate the potential of Cas9/guide RNA (gRNA)-based gene-drive systems linked to dual antiparasite effector genes to spread rapidly through mosquito populations. Two strains have an autonomous gene-drive system coupled to dual anti-Plasmodium falciparum effector genes comprising single-chain variable fragment monoclonal antibodies targeting parasite ookinetes and sporozoites in the African malaria mosquitoes Anopheles gambiae (AgTP13) and Anopheles coluzzii (AcTP13). The gene-drive systems achieved full introduction within 3 to 6 mo after release in small cage trials. Life-table analyses revealed no fitness loads affecting AcTP13 gene-drive dynamics but AgTP13 males were less competitive than wild types. The effector molecules reduced significantly both parasite prevalence and infection intensities. These data supported transmission modeling of conceptual field releases in an island setting that shows meaningful epidemiological impacts at different sporozoite threshold levels (2.5 to 10 k) for human infection by reducing malaria incidence in optimal simulations by 50 to 90% within as few as 1 to 2 mo after a series of releases, and by ≥90% within 3 mo. Modeling outcomes for low sporozoite thresholds are sensitive to gene-drive system fitness loads, gametocytemia infection intensities during parasite challenges, and the formation of potentially drive-resistant genome target sites, extending the predicted times to achieve reduced incidence. TP13-based strains could be effective for malaria control strategies following validation of sporozoite transmission threshold numbers and testing field-derived parasite strains. These or similar strains are viable candidates for future field trials in a malaria-endemic region.

Engineering a Self-Assembled Protein Cage for Targeted Dual Functionalization.

Self-assembled protein cages are attractive scaffolds for organizing various proteins of interest (POIs) toward applications in synthetic biology and medical science. However, specifically attaching multiple POIs to a single protein cage remains challenging, resulting in diversity among the functionalized particles. Here, we present the engineering of a self-assembled protein cage, DTMi3ST, capable of independently recruiting two different POIs using SpyCatcher (SC)/SpyTag (ST) and DogCatcher (DC)/DogTag (DT) chemistries, thereby reducing variability between assemblies. Using fluorescent proteins as models, we demonstrate controlled targeting of two different POIs onto DTMi3ST protein cages both in vitro and inside living cells. Furthermore, dual functionalization of the DTMi3ST protein cage with a membrane-targeting peptide and ß-galactosidase resulted in the construction of membrane-bound enzyme assemblies in Escherichia coli, leading to a 69.6% enhancement in substrate utilization across the membrane. This versatile protein cage platform provides dual functional nanotools for biological and biomedical applications.

Virus-like Particles Armored by an Endoskeleton.

Many virus-like particles (VLPs) have good chemical, thermal, and mechanical stabilities compared to those of other biologics. However, their stability needs to be improved for the commercialization and use in translation of VLP-based materials. We developed an endoskeleton-armored strategy for enhancing VLP stability. Specifically, the VLPs of physalis mottle virus (PhMV) and Qß were used to demonstrate this concept. We built an internal polymer "backbone" using a maleimide-PEG15-maleimide cross-linker to covalently interlink viral coat proteins inside the capsid cavity, while the native VLPs are held together by only noncovalent bonding between subunits. Endoskeleton-armored VLPs exhibited significantly improved thermal stability (95 °C for 15 min), increased resistance to denaturants (i.e., surfactants, pHs, chemical denaturants, and organic solvents), and enhanced mechanical performance. Single-molecule force spectroscopy demonstrated a 6-fold increase in rupture distance and a 1.9-fold increase in rupture force of endoskeleton-armored PhMV. Overall, this endoskeleton-armored strategy provides more opportunities for the development and applications of materials.

A complete methyl-lysine binding aromatic cage constructed by two domains of PHF2.

The N-terminal half of PHF2 harbors both a plant homeodomain (PHD) and a Jumonji domain. The PHD recognizes both histone H3 trimethylated at lysine 4 and methylated nonhistone proteins including vaccinia-related kinase 1 (VRK1). The Jumonji domain erases the repressive dimethylation mark from histone H3 lysine 9 (H3K9me2) at select promoters. The N-terminal amino acid sequences of H3 (AR2TK4) and VRK1 (PR2VK4) bear an arginine at position 2 and lysine at position 4. Here, we show that the PHF2 N-terminal half binds to H3 and VRK1 peptides containing K4me3, with dissociation constants (KD values) of 160 nM and 42 nM, respectively, which are 4 × and 21 × lower (and higher affinities) than for the isolated PHD domain of PHF2. X-ray crystallography revealed that the K4me3-containing peptide is positioned within the PHD and Jumonji interface, with the positively charged R2 residue engaging acidic residues of the PHD and Jumonji domains and with the K4me3 moiety encircled by aromatic residues from both domains. We suggest that the micromolar binding affinities commonly observed for isolated methyl-lysine reader domains could be improved via additional functional interactions within the same polypeptide or its binding partners.

Low-cost, portable, easy-to-use kiosks to facilitate home-cage testing of non-human primates during vision-based behavioral tasks.

Non-human primates (NHPs), especially rhesus macaques, have significantly contributed to our understanding of the neural computations underlying human vision. Besides the established homologies in the visual brain areas between these species and our ability to probe detailed neural mechanisms in monkeys at multiple scales, NHPs' ability to perform human-like visual behavior makes them an extremely appealing animal model of human vision. Traditionally, such behavioral studies have been conducted in controlled laboratory settings, offering experimenters tight control over variables like luminance, eye movements, and auditory interference. However, in-lab experiments have several constraints, including limited experimental time, the need for dedicated human experimenters, additional lab space requirements, invasive surgeries for head-post implants, and extra time and training for chairing and head restraints. To overcome these limitations, we propose adopting home-cage behavioral training and testing of NHPs, enabling the administration of many vision-based behavioral tasks simultaneously across multiple monkeys with reduced human personnel requirements, no NHP head restraint, and monkeys' unrestricted access to experiments. In this article, we present a portable, low-cost, easy-to-use kiosk system developed to conduct home-cage vision-based behavioral tasks in NHPs. We provide details of its operation and build to enable more open-source development of this technology. Furthermore, we present validation results using behavioral measurements performed in the lab and in NHP home cages, demonstrating the system's reliability and potential to enhance the efficiency and flexibility of NHP behavioral research.

From caged compounds with isolated U atoms to frustrated magnets with 2- or 3-atom clusters: a review of Al-rich uranium aluminides with transition metals.

Crystal structures and physical properties of four families of Al-rich ternary uranium compounds with transition metals (TE) are reviewed, namely UTE2Al20, UTE2Al10, U6TE4Al43, and U3TE4Al12. The compounds can be described as consisting of 1 (isolated), 2 (dumbbells) or 3 (triangles) uranium atom clusters, surrounded (1-2-20, 1-2-10 and 6-4-43) or not (3-4-12) by large cages, which strongly influence their magnetic and related properties. Indeed, the ground states of the described systems evolve from Curie-like paramagnetism in the case of the phases with well-isolated, single U-atoms, to complex magnetic order or possible frustrated magnetism in the case of the systems with uranium triangles forming a breathing kagome lattice. We argue that the four families of uranium aluminides described in this review provide a unique opportunity to study magnetic interactions between U magnetic moments while gradually increasing the number of their nearest magnetic neighbors, and may also be helpful in understanding the fundamental origin of magnetic freezing phenomena.

Isomorphous Substitution of Organic Cage Crystal by Pd Nanoclusters for Selective Hydrogenation.

For supporting active metal, the cavity confinement and mass transfer facilitation lie not in one sack, a trade-off between high activity and good stability of the catalyst is present. Porous organic cages (POCs) are expected to break the trade-off when metal particles are properly loaded. Herein, three organic cages (CC3, RCC3, and FT-RCC3) are employed to support Pd nanoclusters for catalytic hydrogenation. Subnanometer Pd clusters locate differently in different cage frameworks by using the same reverse double-solvents approach. Compared with those encapsulated in the intrinsic cavity of RCC3 and anchored on the outer surface of CC3, the Pd nanoclusters orderly assembled in FT-RCC3 crystal via isomorphous substitution exhibit superior activity, high selectivity, and good stability for semi-hydrogenation of phenylacetylene. Isomorphous substitution of FT-RCC3 crystal by Pd nanoclusters is originated from high crystallization capacity of FT-RCC3 and specific interaction of each Pd nanocluster with four cage windows. Both confinement function and H2 accumulation capacity of FT-RCC3 are fully utilized to support active Pd nanoclusters for efficient selective hydrogenation. The present results provide a new perspective to the heterogeneous catalysis field in terms of crystalizing metal nanoclusters in POC framework and outside the cage for making the best use of both parts.

Unlocking High Porosity: Post-Synthetic Solvothermal Treatment of Cu-Paddlewheel Based Metal-Organic Cages.

Metal-organic cages (MOCs) have garnered significant attention due to their unique discrete structures, intrinsic porosity, designability, and tailorability. However, weak inter-cage interactions, such as van der Waals forces and hydrogen bonding can cause solid-state MOCs to lose structural integrity during desolvation, leading to the loss of porosity. In this work, a novel strategy to retain the permanent porosity of Cu-paddlewheel-based MOCs, enabling their use as heterogeneous catalysts is presented. Post-synthetic solvothermal treatments in non-coordinating solvents, mesitylene, and p-xylene, effectively preserve the packing structures of solvent-evacuated MOCs while preventing cage agglomeration. The resulting MOCs exhibit an exceptional N2 sorption capacity, with a high surface area (SBET = 1934 m2 g-1 for MOP-23), which is among the highest reported for porous MOCs. Intriguingly, while the solvothermal treatment reduced Cu(II) to Cu(I) in the Cu-paddlewheel clusters, the MOCs with mixed-valenced Cu(I)/Cu(II) maintained their crystallinity and permanent porosity. The catalytic activities of these MOCs are successfully examined in copper(I)-catalyzed hydrative amide synthesis, highlighting the prospect of MOCs as versatile reaction platforms.

Encasing Few-Layer MoS2 within 2D Ordered Cubic Graphitic Cages to Smooth Trapping-Conversion of Lithium Polysulfides for Dendrite-Free Lithium-Sulfur Batteries.

The industrialization of lithium-sulfur (Li-S) batteries faces challenges due to the shuttling effect of lithium polysulfides (LiPSs) and the growth of lithium dendrites. To address these issues, a simple and scalable method is proposed to synthesize 2D membranes comprising a single layer of cubic graphitic cages encased with few-layer, curved MoS2. The distinctive 2D architecture is achieved by confining the epitaxial growth of MoS2 within the open cages of a 2D-ordered mesoporous graphitic framework (MGF), resulting in MoS2@MGF heterostructures with abundant sulfur vacancies. The experimental and theoretical studies establish that these MoS2@MGF membranes can act as a multifunctional interlayer in Li-S batteries to boost their comprehensive performance. The inclusion of the MoS2@MGF interlayer facilitates the trapping and conversion kinetics of LiPSs, preventing their shuttling effect, while simultaneously promoting uniform lithium deposition to inhibit dendrite growth. As a result, Li-S batteries with the MoS2@MGF interlayer exhibit high electrochemical performance even under high sulfur loading and lean electrolyte conditions. This work highlights the potential of designing advanced MoS2-encased heterostructures as interlayers, offering a viable solution to the current limitations plaguing Li-S batteries.

Codelivery of Dual Gases with Metal-Organic Supramolecular Cage-Based Microenvironment-Responsive Nanomedicine for Atherosclerosis Therapy.

Atherosclerosis (AS) is a common cause of coronary heart disease and stroke. The delivery of exogenous H2S and in situ production of O2 within atherosclerotic plaques can help suppress inflammatory cell infiltration and alleviate disease progression. However, the uncontrolled release of gas donors hinders achieving effective drug concentrations and causes toxic effects. Herein, diallyl trisulfide (DATS)-loaded metal-organic cage (MOC)-68-doped MnO2 nanoparticles are developed as a microenvironment-responsive nanodrug with the capacity for the in situ co-delivery of H2S and O2 to inflammatory cells within plaques. This nanomedicine exhibited excellent monodispersity and stability and protected DATS from degradation in the circulation. In vitro studies showed that the nanomedicine reduced macrophage polarization toward an inflammatory phenotype and inhibited the formation of foam cells, while suppressing the expression of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and interleukin-1ß. In a mouse model of ApoE-/- genotype, the nanomedicine reduces the plaque burden, inflammatory infiltration, and hypoxic conditions within the plaques. Furthermore, the treatment process and therapeutic effects can be monitored by magnetic resonance image (MRI), in real time upon Mn2+ release from the acidic- and H2O2- microenvironment-responsive MnO2 nanoparticles. The DATS-loaded MOC-68-doped MnO2-based nanodrug holds great promise as a novel theranostic platform for AS.

Iron mobilization from intact ferritin: effect of differential redox activity of quinone derivatives with NADH/O2 and in situ-generated ROS.

Ferritins are multimeric nanocage proteins that sequester/concentrate excess of free iron and catalytically synthesize a hydrated ferric oxyhydroxide bio-mineral. Besides functioning as the primary intracellular iron storehouses, these supramolecular assemblies also oversee the controlled release of iron to meet physiologic demands. By virtue of the reducing nature of the cytosol, reductive dissolution of ferritin-iron bio-mineral by physiologic reducing agents might be a probable pathway operating in vivo. Herein, to explore this reductive iron-release pathway, a series of quinone analogs differing in size, position/nature of substituents and redox potentials were employed to relay electrons from physiologic reducing agent, NADH, to the ferritin core. Quinones are well known natural electron/proton mediators capable of facilitating both 1/2 electron transfer processes and have been implicated in iron/nutrient acquisition in plants and energy transduction. Our findings on the structure-reactivity of quinone mediators highlight that iron release from ferritin is dictated by electron-relay capability (dependent on E1/2 values) of quinones, their molecular structure (i.e., the presence of iron-chelation sites and the propensity for H-bonding) and the type/amount of reactive oxygen species (ROS) they generate in situ. Juglone/Plumbagin released maximum iron due to their intermediate E1/2 values, presence of iron chelation sites, the ability to inhibit in situ generation of H2O2 and form intramolecular H-bonding (possibly promotes semiquinone formation). This study may strengthen our understanding of the ferritin-iron-release process and their significance in bioenergetics/O2-based cellular metabolism/toxicity while providing insights on microbial/plant iron acquisition and the dynamic host-pathogen interactions.

Silicon Chalcogenide Cage Compounds: New Structures Derived from the Bicyclic Silicon(I) Ring Compound Si4 {N(SiMe3 )Mes}4.

The bicyclic silicon(I) ring compound Si4 {N(SiMe3 )Mes}4 (2) was used as starting material in reactions with chalcogens and chalcogen transfer agents at low temperatures. This resulted in the selective formation of new cage compounds. With Me3 NO, a silicon oxide with adamantane-type cage 3 was isolated that represents the first isolated T4 silsesquioxane. Reactions with propylenesulfide and red selenium gave direct access to defect heterocubane-type cages 4 and 5 with three Si-Si bonds wherein the silicon atoms adopt different low oxidation states of +I and +III. A reaction with elemental tellurium even occurs below room temperature to provide ditelluro-tetrasila-tricyclohexane 6.

Mausolates: Large-Cavity Chelates with Potential as Delivery Vehicles in Nuclear Medicine.

A new type of diborate clathrochelate (cage) ligand featuring nine inwardly pointing nitrogen donors that form a large, rigid cavity, termed a mausolate, is presented. The cavity size and high denticity make this an attractive delivery vehicle for large radionuclides in nuclear medicine. Metal mausolate complexes are stable to air and water (neutral pH) and display extremely high thermal stability (>400 °C). Lanthanide uptake by the mausolate ligand occurs rapidly in solution at room temperature and once complexed, the lanthanide ions are not displaced by a 250-fold excess of a competitive lanthanide salt over more than one week.

A Chiral [2+3] Covalent Organic Cage Based on 1,1'-Bi-2-naphthol (BINOL) Units.

A [2+3] chiral covalent organic cage is produced through a dynamic covalent chemistry approach by mixing two readily available building units, viz. an enantiopure 3,3'-diformyl 2,2'-BINOL compound (A) with a triamino spacer (B). The two enantiomeric (R,R,R) and (S,S,S) forms of the cage C are formed nearly quantitatively thanks to the reversibility of the imine linkage. The X-ray diffraction analysis of cage (S,S,S)-C highlights that the six OH functions of the BINOL fragments are positioned inside the cage cavity. Upon reduction of the imine bonds of cage C, the amine cage D is obtained. The ability of the cage D to host the 1-phenylethylammonium cation (EH+) as a guest is evaluated through UV, CD and DOSY NMR studies. A higher binding constant for (R)-EH+ cation (Ka=1.7 106±10 % M-1) related to (S)-EH+ (Ka=0.9 106±10 % M-1) is determined in the presence of the (R,R,R)-D cage. This enantiopreference is in close agreement with molecular dynamics simulation.

Polyhedral Oligomeric Silsesquioxane D3h-(RSiO1.5)14.

While smaller polyhedral oligomeric silsesquioxanes TnRn (POSS) are readily accessible or even commercially available, unambiguously authenticated larger systems (n>12) have barely been reported. Synthesis and isolation procedures are lengthy, and yields are often very low. Herein, we present the surprisingly straightforward and high-yielding access to the phenyl-substituted derivative of a so far only postulated second D3h-symmetric T14 isomer and with that the largest crystallographically characterized POSS cage with organic substituents. Treatment of the commercially available incompletely condensed T7Ph7(OH)3 silsesquioxane with catalytic amounts of trifluoromethanesulfonic acid results in high yields of the T14Ph14 framework, which is isolated in crystalline form by a simple work-up. D3h-T14Ph14 was analyzed by single crystal X-ray diffraction, multinuclear NMR spectroscopy and thermal analysis. The relative energies of all four theoretically possible T14Ph14 isomers were determined by optimization of the corresponding structure using DFT methods.

A Cyclotriveratrylene Solvent-Dependent Chiral Switch.

Chiral molecular switches are attracting attention as they could pave the way to chiral molecular machines. Herein, we report on the design and synthesis of a single molecule chiral switch based on a cyclotriveratrylene scaffold, in which the chirality inversion is controlled by the solvent. Hemicryptophanes are built around a C3 cyclotriveratrylene chiral unit, with either M or P handedness, connected to another tripod and usually displaying an "out" configuration. Here, we demonstrate that solvents are able to control the "in" and "out" configurations of the CTV unit, creating a chiral molecular switch from (M/P)"in" to (P/M)"out" handedness. The full characterization of the "in" and "out" configurations and of the chirality switch were made possible by combining NMR, HPLC, ECD, DFT and molecular dynamics. Interestingly, bulky aromatic solvents such as 2-t-butylphenol favor the "in" configuration while polar aprotic solvents such as acetone favor the "out" configuration. This chiral switch was found to be fully reversible allowing the system to oscillate between two different M and P configurations several times upon the action of solvents stimuli.

Stabilization of Lantern-Type Metal-Organic Cages (MOCs) by Protective Control of Ligand Exchange Rates.

Self-assembling systems in nature display remarkable complexity with assemblies of different sub-units to generate functional species. Synthetic analogues of such systems are a challenge, often requiring the ability to bias distributions that are under thermodynamic assembly control. Using lantern-type MOCs (metal-organic cages) as a prototypical self-assembling system, herein we explore the role that steric bulk plays in controlling the exchange rate of ligands in paddlewheel-based assemblies, and thus the stability of cages, in competitive self-assembling scenarios. The effective lifetime of the lantern-type MOCs varies over an order of magnitude depending on the steric bulk proximal to the metal nodes with lifetimes of the cages ranging from tens of minutes to several hours. The bulk of the coordinating solvents likewise reduces the rate of ligand exchange, and thus yields longer-lived species. Understanding this subtle effect has implications for controlling the stability of complex assemblies in competitive environments with implications for guest release and application.