ChemSystemsChem最新文献

Block copolymer-based polymersomes are important building blocks for the bottom-up design of protocells and are considered advantageous over liposomes due to their higher mechanical stability and chemical versatility. Endowing both types of vesicles with capabilities for transmembrane transport is important for creating nanoreactor functionality and has been achieved by insertion of protein nanopores, even into comparably thick polymersome membranes. Still, the design space for protein nanopores is limited and higher flexibility might be accessible by de novo design of DNA nanopores, which have thus far been limited largely to liposome systems. Here, we introduce the successful insertion of two different 3D DNA origami nanopores into PMOXA-b-PDMS-b-PMOXA polymersomes, and confirm pore formation by dye influx studies and microscopy. This research thus opens the further design space of this versatile class of large DNA origami nanopores for polymersome-based functional protocells.

The Front Cover shows a light microscopy image of metabolite coacervates. A graphic representation of a metabolic network is projected over the coacervate protocells, containing illustrations that depict different steps in the emergence of life on Earth. Small molecules react to form more complex molecules, which eventually partake in reaction networks. This work shows how metabolites present in these early networks are able to phase separate and form stable coacervate droplets. The coacervates are able to compartmentalize metabolites and increase reaction rates, providing an attractive model for the first generation of protocells. More information can be found in the Research Article by Evan Spruijt and co-workers.

The front cover artwork is provided by the Spruijt group from the Radboud University in Nijmegen. The image shows a metabolic reaction pathway projected over a microscopy image of metabolite coacervates. Read the full text of the Research Article at 10.1002/syst.202200004.

Mackinawite has unique structural properties and reactivities when compared to other iron sulfides. Herein we provide evidence for the mackinawite-supported reduction of KCN into various reduced compounds under primordial conditions. We proposed a reaction mechanism based on the nucleophilic attack by the deprotonated mackinawite -SH surface groups at the carbon atom of HCN. The initial binding of the substrate and the subsequent reduction events are supported by DFT calculations and further experiments using other substrates, such as KSCN, KOCN and CS₂. Until now, conversion of CN⁻ into CH₄ and NH₃ has been limited to nitrogenase cofactors or molecular Fe-CN complexes. Our study provides evidence for mackinawite-supported cleavage of the C−N bond under ambient conditions, which opens new avenues for investigation of other substrates for mackinawite-supported reactions while shedding light on the relevance of this type of reaction to the origin of life on Earth.

Addition of CaCl₂ into a highly alkaline phosphate buffer results in the generation of submerged transparent chemobrionic bubbles mimicking jellyfish that are stable and malleable. A compartmentalized O₂-generating reaction triggered the growth of regular vertical chemical gardens from the bubble through a gas micro-rocket propelled mechanism. The bubbles can mechanically separate to yield two daughter bubbles in a process reminiscent of cytokinesis or natural jellyfish regeneration, and then re-grow through new injection of CaCl₂. Finally, loading of E. coli bacteria genetically engineered to exert green fluorescence inside the bubbles was demonstrated in a biomimetic analogue of “symbiosis”.

Lipid rafts are ordered lipid domains that are enriched in saturated lipids, such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have not been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here, we report that microscopic GM1-enriched domains can form in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that the propensity of EphA2 to oligomerize is similar in EphA2-enriched and -depleted domains. However, surprisingly, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biophysical chemistry of lipid rafts.

The front cover artwork is provided by İrep Gözen group at the University of Oslo. The image shows primitive cell-like compartments which have spontaneously emerged from a crack in rock-forming mineral oligoclase. Read the full text of the Article at 10.1002/syst.202100040.

The Front Cover shows primitive cell-like compartments which have spontaneously emerged from a crack in rock-forming mineral oligoclase. More information can be found in the Article by Irep Gözen and co-workers.

This report describes a method to obtain multicellular shaped compartments made by lipids growing from a sponge-like porous structure. Each compartment is several tens of micrometers in diameter and separated by membranes comprised of phospholipid and amphipathic molecules. The multi-compartment structure spontaneously grew to a millimeter scale, driven by an ionic concentration difference between the interior and exterior environments of the sponge. These compartments can also easily incorporate hydrophilic species as a well as smaller materials such as liposomes. Additionally, we showed that mechanical squeezing of the sponge was also effective in producing multicellular bodies. These simple methods to obtain large-scale multicellular compartment of lipid membrane will help future designs and trials of chemical communications on artificial cells.

The cell is a crowded environment where a relevant fraction of the available space is occupied by proteins, nucleic acids, and metabolites. Here we discuss recent advancements in the understanding of crowding effects on intrinsically disordered proteins. Differently from their structured counterparts, these proteins do not adopt a stable three-dimensional structure and remain flexible and dynamic in solution. The physics of polymers and colloids provides a framework to interpret how crowding modulates conformations, dynamics, and interactions of disordered proteins. Flory-Huggins models enable rationalizing the different degree of compaction induced by crowding agents in terms of depletion interactions. The same interactions modulate the diffusion of the disordered proteins in a crowded milieu and the association and dissociation rates when interacting with a ligand. Altogether, this theoretical framework provides new insights into the interpretation of the effects of the cellular environment on disordered proteins.