Urotensin II (UII) and UII-related peptide (URP) are vasoactive peptide hormones causing strong vasoconstriction or vasodilation, depending on the type of blood vessel. In humans, the active forms are resulting from proteolytic cleavage of their inactive precursor protein. In blood plasma, a defined protease converting the inactive UII- and URP precursors into their active forms has not been identified yet. Using mass spectrometry-based enzyme screening for detecting UII and URP-converting enzymes, the human plasma fraction Cohn IV-4 was chromatographed, and the resulting fractions were screened for UII- or URP-generating activity. Plasma kallikrein (PK) as a UII- and URP-generating protease was identified. URP generation was also found for the serine protease factor XIa, plasmin, thrombin, and, to a smaller extent, factor XIIa. It was demonstrated that in the Cohn IV-4 fraction, PK accounts for a significant amount of UII- and URP-generating activity.

Three stop codons (UAA, UAG and UGA) terminate protein synthesis and are almost exclusively recognized by release factors. Here, we design de novo transfer RNAs (tRNAs) that efficiently decode UGA stop codons in Escherichia coli . The tRNA designs harness various functionally conserved aspects of sense-codon decoding tRNAs. Optimization within the TΨC-stem to stabilize binding to the elongation factor, displays the most potent effect in enhancing suppression activity. We determine the structure of the ribosome in a complex with the designed tRNA bound to a UGA stop codon in the A site at 2.9 Å resolution. In the context of the suppressor tRNA, the conformation of the UGA codon resembles that of a sense-codon rather than when canonical translation termination release factors are bound, suggesting conformational flexibility of the stop codons dependent on the nature of the A-site ligand. The systematic analysis, combined with structural insights, provides a rationale for targeted repurposing of tRNAs to correct devastating nonsense mutations that introduce a premature stop codon.

Coronavirus disease 2019 (COVID-19) can damage cerebral small vessels and cause neurological symptoms. Here we describe structural changes in cerebral small vessels of patients with COVID-19 and elucidate potential mechanisms underlying the vascular pathology. In brains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected individuals and animal models, we found an increased number of empty basement membrane tubes, so-called string vessels representing remnants of lost capillaries. We obtained evidence that brain endothelial cells are infected and that the main protease of SARS-CoV-2 (M pro ) cleaves NEMO, the essential modulator of nuclear factor-κB. By ablating NEMO, M pro induces the death of human brain endothelial cells and the occurrence of string vessels in mice. Deletion of receptor-interacting protein kinase (RIPK) 3, a mediator of regulated cell death, blocks the vessel rarefaction and disruption of the blood–brain barrier due to NEMO ablation. Importantly, a pharmacological inhibitor of RIPK signaling prevented the M pro -induced microvascular pathology. Our data suggest RIPK as a potential therapeutic target to treat the neuropathology of COVID-19.

Withdrawal statement“The authors have withdrawn their manuscript because the authors need to re-organize the data and writing, meanwhile more experimental evidence from human cellular N-glycome will be added to support their viewpoints. In this preprint, only one human cell line, Acute Promyelocytic Leukemia (APL) cells, was deeply investigated to show the N-glycome landscape. To provide the shared features of human N-glycome, more human cells should be investigated. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.”

The analysis of proteomes directly from tissues requires the proteins to be released from the cells and their compartments and solubilized, which usually is achieved by mechanical homogenization. It was recently shown, that sampling of tissues with the novel picosecond infrared laser (PIRL) offers higher yields of proteins with respect to the total amount and total number of individual proteins in comparison to mechanical homogenization. Furthermore, proteins obtained from tissues by homogenization with PIRL are significantly less enzymatically degraded, giving improved access to the original composition of proteoforms. The effective cold vaporization of tissue with PIRL is very soft, which is responsible for the phenomenon, that even enzymatic activities of proteins in the tissue aerosol are maintained. In contrast, the energy following irradiation of tissue with microsecond infrared laser (MIRL) pulses is not thermally and acoustically confined to the ablated volume. In this study, PIRL (1 J·cm-2) and MIRL (40-60 J·cm-2) were compared for sampling different tissue types for bottom-up proteomics. We showed that PIRL at low fluence is optimal for soft tissue and desired in scenarios were enzymatic activities of proteins must be maintained as well as were no residual tissue damage is a requirement. MIRL could be well suited for scenarios were enzymatic activities must be suppressed within the intact tissue and thermal and acoustic damage is not a concern.

Colloidal approaches allow for the synthesis of Au nanoclusters (NCs) with atomic precision and sizes ranging from a few to hundreds of atoms.