Carsten Scavenius

Insect biomass produced at large scale is increasingly considered a sustainable alternative to conventional feed ingredients, making it important to understand how rearing conditions affect both biomass yield and nutritional composition. Rearing temperature is a controllable production factor that shapes growth, development and macronutrient allocation in yellow mealworm ( Tenebrio molitor ), but its effects on fatty acid and amino acid composition remain poorly resolved. We reared T. molitor larvae at 23, 28 and 33 °C until first pupation and measured developmental time, survival, growth, water content, lipid and protein fractions and fatty acid and amino acid composition. Time to first pupation was shortest at 28 °C, whereas survival was lowest at 33 °C. Individual wet mass increased with temperature, but total wet and dry biomass did not differ among treatments. Higher temperatures reduced water content from 65.3 to 61.6% and shifted dry-mass composition towards higher lipid content, which increased from 31.6 to 37.1%, and lower protein content, which decreased from 35.1 to 33.7%. Increasing rearing temperature raised the proportions of myristic, palmitic and oleic acids, while reducing linoleic and α -linolenic acids, thereby shifting the profile towards more saturated and monounsaturated fatty acids and fewer polyunsaturated fatty acids. This resulted in the lowest n-6/n-3 ratio at 23 °C (n-6/n-3 = 18.4), although ratios remained high across treatments. In contrast, amino acid composition was largely stable, with glycine being the only amino acid significantly affected. Overall, rearing temperature can be used to modify selected production and compositional traits in T. molitor biomass, with strong effects on individual growth, lipid/protein fractions and fatty acid composition.

Natural pentamer dodecahedra (Ddhs) span six orders of magnitude in diameter. Among proteins, only two catalytic Ddhs have been structurally characterized: lumazine synthase (LS) and the core of pyruvate dehydrogenase (PDH). Zuzalysin (ZUZ) is a ≈95‐kDa metallopeptidase secreted for virulence by Porphyromonas gingivalis . Calcium converts latent flexible monomers into active ≈0.5‐MDa pentamers that further assemble hierarchically into bipentamers, tripentamers, and a ≈5.6‐MDa, ≈355‐Å virus‐like dodecahedron (Ddh _ZUZ ). Experimental structures (1.8–3.6 Å) across these states reveal the molecular basis of activation, association, and catalysis, culminating in Ddh _ZUZ , which is physiologic, exceeds small viral capsids, and has 20 main entry pores and 60 lumen‐facing active sites. ZUZ represents the largest catalytic protein assembly resolved at high resolution, exceeding LS, PDH, and major peptidase complexes in size and/or resolution.

Natural pentamer dodecahedra (Ddhs) span six orders of magnitude in diameter. Among proteins, only two catalytic Ddhs have been structurally characterized: lumazine synthase (LS) and the core of pyruvate dehydrogenase (PDH). Zuzalysin (ZUZ) is a ≈95‐kDa metallopeptidase secreted for virulence by Porphyromonas gingivalis . Calcium converts latent flexible monomers into active ≈0.5‐MDa pentamers that further assemble hierarchically into bipentamers, tripentamers, and a ≈5.6‐MDa, ≈355‐Å virus‐like dodecahedron (Ddh _ZUZ ). Experimental structures (1.8–3.6 Å) across these states reveal the molecular basis of activation, association, and catalysis, culminating in Ddh _ZUZ , which is physiologic, exceeds small viral capsids, and has 20 main entry pores and 60 lumen‐facing active sites. ZUZ represents the largest catalytic protein assembly resolved at high resolution, exceeding LS, PDH, and major peptidase complexes in size and/or resolution.

The concept of protein corona formation around extracellular vesicles (EVs) has given birth to new insights into how cells may recognize EVs by proteins presented at the EV surface. Here we present spatially resolved proteomics using the biotin ligase TurboID to map proteins interacting at the EV surface, without a need for physical isolation of the EV‐corona complexes. TurboID promiscuously biotinylates nearby proteins within a few nm distance from the fused ‘bait’ protein. We genetically engineered EVs by modifying CD63 as the bait protein to which TurboID was fused facing outward to map EV corona proteins. Biotinylated proteins were then analysed by Western blotting and liquid chromatography‐mass spectrometry. Western blots revealed protein patterns that are distinct depending on the localization of the fused TurboID. The mass spectrometry analysis identified many of the serum proteins commonly known to form a corona around a synthetic solid nanoparticle, also supporting those previously reported through the physical isolation approaches. Rather striking is, however, the EV corona footprint of endogenous proteins that tells us about the EV biogenesis and what the intrinsic endogenous corona might look like. This approach, which we coined EV‐SPEC (Spatial Proteomics of Endogenous Corona), has thus the potential to revolutionize our understanding of EV biology by shifting the focus from the EVs themselves to the proteins that make up the corona, or how the cell ‘sees’ them, in analogy with the biomolecular corona extensively characterized for synthetic nanoparticles.

The Gram-negative β-barrel assembly machinery (BAM) complex catalyses the folding and membrane insertion of newly synthesized β-barrel outer membrane proteins. The BAM is structurally conserved, but most studies have focused on Gammaproteobacteria. Here, using single-particle cryogenic electron microscopy, quantitative proteomics and functional assays, we show that the BAM complex is distinct within the Bacteroidota. Cryogenic electron microscopy structures of BAM complexes from the human gut symbiont Bacteroides thetaiotaomicron (3.3 Å) and the human oral pathogen Porphyromonas gingivalis (3.2 Å) show similar, seven-component complexes of ~325 kDa. The complexes are mostly extracellular and comprise canonical BamA and BamD; an integral, essential outer membrane protein, BamG, that associates with BamA; and four surface-exposed lipoproteins: BamH–K. Absent from the BAM in Pseudomonadota, BamG–K form a large, extracellular dome that may confer additional functionality to enable the folding and assembly of β-barrel–surface-exposed lipoprotein complexes that are a hallmark of the Bacteroidota. Our findings develop our understanding of fundamental biological processes in an important bacterial phylum.

The origin of the molecular building blocks of life is a central question in science. A few α-amino acids such as glycine, the simplest proteinogenic amino acid, have been detected in meteorites and comets, indicating an extraterrestrial origin for some prebiotic molecules. However, the formation of peptides, short chains of α-amino acids linked by peptide bonds, under astrophysical conditions has remained unresolved. Here we show that the building blocks of proteins can form in interstellar ice analogues exposed to ionising radiation, without the presence of liquid water. Using isotopically labelled glycine irradiated with protons at cryogenic temperatures, we detect the formation of glycylglycine, the simplest dipeptide, along with deuterated and nondeuterated water as by-products. Peptide bond formation is confirmed by infrared spectroscopy and high-resolution mass spectrometry, which also reveal the production of other complex organic species. These findings demonstrate a non-aqueous route to peptide formation under space-like conditions and suggest that such molecules could form in the cold interstellar medium and be incorporated into forming planetary systems. Our results challenge aqueous-centric models of early biochemical evolution and broaden potential settings for the origins of life.