The rockefeller university

Hepatitis B virus (HBV) is a small double -stranded DNA virus that chronically infects 296 million people. Over half of its compact genome encodes proteins in two overlapping reading frames, and during evolution, multiple selective pressures can act on shared nucleotides. This study combines an RNA -based HBV cell culture system with deep mutational scanning (DMS) to uncouple cis - and trans -acting sequence requirements in the HBV genome. The results support a leaky ribosome scanning model for polymerase translation, provide a fitness map of the HBV polymerase at single -nucleotide resolution, and identify conserved prolines adjacent to the HBV polymerase termination codon that stall ribosomes. Further experiments indicated that stalled ribosomes tether the nascent polymerase to its template RNA, ensuring cis -preferential RNA packaging and reverse transcription of the HBV genome.

Recombinant expression of proteins, propelled by therapeutic antibodies, has evolved into a multibillion dollar industry. Essential here is the quality control assessment of critical attributes, such as sequence fidelity, proper folding, and posttranslational modifications. Errors can lead to diminished bioactivity and, in the context of therapeutic proteins, an elevated risk for immunogenicity. Over the years, many techniques were developed and applied to validate proteins in a standardized and high- throughput fashion. One parameter has, however, so far been challenging to assess. Disulfide bridges, covalent bonds linking two cysteine residues, assist in the correct folding and stability of proteins and thus have a major influence on their efficacy. Mass spectrometry promises to be an optimal technique to uncover them in a fast and accurate fashion. In this work, we present a unique combination of sample preparation, data acquisition, and analysis facilitating the rapid and accurate assessment of disulfide bridges in purified proteins. Through microwave- assisted acid hydrolysis, the proteins are digested rapidly and artifact-free into peptides, with a substantial degree of overlap over the sequence. The nonspecific nature of this procedure, however, introduces chemical background, which is efficiently removed by integrating ion mobility preceding the mass spectrometric measurement. The nonspecific nature of the digestion step additionally necessitates new developments in data analysis, for which we extended the XlinkX node in Proteome Discoverer to efficiently process the data and ensure correctness through effective false discovery rate correction. The entire workflow can be completed within 1 h, allowing for high-throughput, high-accuracy disulfide mapping.

A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at root s = 13 TeV in 2016-2018, and corresponding to an integrated luminosity of 138 fb(-1). The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260-1000 GeV and 300-1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90-800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90-0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.

Editor's note: This is the 21st article in a series on clinical research by nurses. The series is designed to be used as a resource for nurses to understand the concepts and principles essential to research. Each column will present the concepts that underpin evidence-based practice-from research design to data interpretation. To see all the articles in the series, go to https://links.lww.com/AJN/A204.

In this issue of Molecular Cell, Yang et al.(1) find that arginine-to-cysteine substitutants are enriched in a subset of lung cancer proteomes, potentiated by arginine deprivation, and promote resistance to chemotherapy.

Following tissue damage, epithelial stem cells (SCs) are mobilized to enter the wound, where they confront harsh inflammatory environments that can impede their ability to repair the injury. Here, we investigated the mechanisms that protect skin SCs within this inflammatory environment. Characterization of gene expression profiles of hair follicle SCs (HFSCs) that migrated into the wound site revealed activation of an immune -modulatory program, including expression of CD80, major histocompatibility complex class II (MHCII), and CXC motif chemokine ligand 5 (CXCL5). Deletion of CD80 in HFSCs impaired re-epithelialization, reduced accumulation of peripherally generated Treg (pTreg) cells, and increased infiltration of neutrophils in wounded skin. Importantly, similar wound healing defects were also observed in mice lacking pTreg cells. Our findings suggest that upon skin injury, HFSCs establish a temporary protective network by promoting local expansion of Treg cells, thereby enabling re-epithelialization while still kindling inflammation outside this niche until the barrier is restored.

Background: Mendelian susceptibility to mycobacterial diseases (MSMD) is a rare clinical syndrome characterized by vulnerability to weakly virulent mycobacterial species, including Bacillus Calmette-Guerin (BCG) vaccines and environmental mycobacteria. Objective: We sought to perform a systematic review of the genetic, immunologic, and clinical findings for reported patients with MSMD. Methods: We searched PubMed, Web of Science, and Scopus databases for publications in English relating to MSMD. All full texts were evaluated for eligibility for inclusion. Two reviewers independently selected the publications, with a third reviewer consulted in cases of disagreement. Results: A primary systematic search and searches of other resources identified 16,155 articles. In total, 158 articles from 63 countries were included in qualitative and quantitative analyses. In total, 830 patients-436 males (52.5%), 369 females (44.5%), and 25 patients of unknown sex (3.0%)-from 581 families were evaluated. A positive family history was reported in 347 patients (45.5%). The patients had a mean age of 10.41 6 0.42 (SEM) years. The frequency of MSMD was highest in Iran, Turkey, and Saudi Arabia. Lymphadenopathy was the most common clinical manifestation of MSMD, reported in 378 (45.5%) cases and multifocal in 35.1%. Fever, organomegaly, and sepsis were the next most frequent findings, reported in 251 (30.2%), 206 (24.8%), and 171 (20.8%) cases, respectively. In total, 299 unique mutations in 21 genes known to be involved in MSMD were reported: 100 missense (34%), 80 indel-frameshift (insertion or deletion, 27%), 53 nonsense (18%), 35 splice site (12%), 10 indel-in frame (2.7%), 6 indel (2%), and 15 large deletion/duplication mutations. Finally, 61% of the reported patients with MSMD had mutations of IL12RB1 (41%) or IFNGR1 (20%). At the time of the report, 177 of the patients (21.3%) were dead and 597 (71.9%) were still alive. Conclusions: MSMD is associated with a high mortality rate, mostly due to impaired control of infection. Preexposure strategies, such as changes in vaccination policy in endemic areas, the establishment of a worldwide registry of patients with MSMD, and precise follow-up over generations in affected families, appear to be vital to decrease MSMD-related mortality.

A search is presented for a third-generation leptoquark (LQ) coupled exclusively to a tau lepton and a b quark. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV recorded with the CMS detector, corresponding to an integrated luminosity of 138 fb(-1). Events with tau leptons and a varying number of jets originating from b quarks are considered, targeting the single and pair production of LQs, as well as nonresonant t-channel LQ exchange. An excess is observed in the data with respect to the background expectation in the combined analysis of all search regions. For a benchmark LQ mass of 2 TeV and an LQ-b-tau coupling strength of 2.5, the excess reaches a local significance of up to 2.8 standard deviations. Upper limits at the 95% confidence level are placed on the LQ production cross section in the LQ mass range 0.5-2.3 TeV, and up to 3 TeV for t-channel LQ exchange. Leptoquarks are excluded below masses of 1.22-1.88 TeV for different LQ models and varying coupling strengths up to 2.5. The study of nonresonant tau tau production through t-channel LQ exchange allows lower limits on the LQ mass of up to 2.3 TeV to be obtained.