Click editing enables programmable genome writing using DNA polymerases and HUH endonucleases.

Genome editing technologies based on DNA-dependent polymerases (DDPs) could offer several benefits compared with other types of editors to install diverse edits. Here, we develop click editing, a genome writing platform that couples the advantageous properties of DDPs with RNA-programmable nickases to permit the installation of a range of edits, including substitutions, insertions and deletions. Click editors (CEs) leverage the 'click'-like bioconjugation ability of HUH endonucleases with single-stranded DNA substrates to covalently tether 'click DNA' (clkDNA) templates encoding user-specifiable edits at targeted genomic loci. Through iterative optimization of the modular components of CEs and their clkDNAs, we demonstrate the ability to install precise genome edits with minimal indels in diverse immortalized human cell types and primary fibroblasts with precise editing efficiencies of up to ~30%. Editing efficiency can be improved by rapidly screening clkDNA oligonucleotides with various modifications, including repair-evading substitutions. Click editing is a precise and versatile genome editing approach for diverse biological applications.

Ancestral sequence reconstruction of Mic60 reveals a residue signature supporting respiration in yeast.

In eukaryotes, the essential process of cellular respiration takes place in the cristae of mitochondria. The protein Mic60 is known to stabilize crista junctions; however, how the C-terminal Mitofilin domain of Mic60 mediates cristae-supported respiration remains elusive. Here, we used ancestral sequence reconstruction to generate Mitofilin ancestors up to and including the last opisthokont common ancestor (LOCA). We found that yeast-lineage derived Mitofilin ancestors as far back as the LOCA rescue respiration. By comparing Mitofilin ancestors with different respiratory phenotypes, we identify four residues that explain the difference between respiration functional yeast- and non-functional animal-derived common Mitofilin ancestors. Our results imply that Mitofilin-supported respiration in yeast stems from a conserved mechanism, and provide a foundation for investigating the divergence of candidate crista junction interactions present during the emergence of eukaryotes.

Preventive health measures in small and medium-sized enterprises: A scoping review on implementation strategies.

OBJECTIVE: To describe implementation strategies for preventive health measures in SMEs and the effectiveness of the strategies on implementation outcomes. METHODS: A literature search was performed in multiple electronic databases. Studies published between 2000 and 2021 that evaluated the implementation of preventive health measures in SMEs were included. Classification of implementation strategies was based on two complementary classification systems. RESULTS: Nineteen studies, of which 5 RCTs were included. Eighteen distinct implementation strategies were reported. All studies applied a combination of implementation strategies, and nearly all reported a positive effect on one or more implementation outcomes: sustainability, acceptability, feasibility, penetration, fidelity, adoption, and appropriateness. CONCLUSIONS: Overall, a positive effect of combined implementation strategies on the implementation outcome(s) was found. The 'distribution of educational materials' and 'provide ongoing consultation' combined show positive effects on sustainability.

Helical reconstruction of VP39 reveals principles for baculovirus nucleocapsid assembly.

Baculoviruses are insect-infecting pathogens with wide applications as biological pesticides, in vitro protein production vehicles and gene therapy tools. Its cylindrical nucleocapsid, which encapsulates and protects the circular double-stranded viral DNA encoding proteins for viral replication and entry, is formed by the highly conserved major capsid protein VP39. The mechanism for VP39 assembly remains unknown. We use electron cryomicroscopy to determine a 3.2 Å helical reconstruction of an infectious nucleocapsid of Autographa californica multiple nucleopolyhedrovirus, revealing how dimers of VP39 assemble into a 14-stranded helical tube. We show that VP39 comprises a distinct protein fold conserved across baculoviruses, which includes a Zinc finger domain and a stabilizing intra-dimer sling. Analysis of sample polymorphism shows that VP39 assembles in several closely-related helical geometries. This VP39 reconstruction reveals general principles for baculoviral nucleocapsid assembly.

Helical reconstruction of VP39 reveals principles for baculovirus nucleocapsid assembly.

Baculoviruses are insect-infecting pathogens with wide applications as biological pesticides, in vitro protein production vehicles and gene therapy tools. Its cylindrical nucleocapsid, which encapsulates and protects the circular double-stranded viral DNA encoding proteins for viral replication and entry, is formed by the highly conserved major capsid protein VP39. The mechanism for VP39 assembly remains unknown. We determined a 3.2 Å electron cryomicroscopy helical reconstruction of an infectious nucleocapsid of Autographa californica multiple nucleopolyhedrovirus, revealing how dimers of VP39 assemble into a 14-stranded helical tube. We show that VP39 comprises a unique protein fold conserved across baculoviruses, which includes a Zinc finger domain and a stabilizing intra-dimer sling. Analysis of sample polymorphism revealed that VP39 assembles in several closely-related helical geometries. This VP39 reconstruction reveals general principles for baculoviral nucleocapsid assembly.

The Implementation of Preventive Health Measures in Small- and Medium-Sized Enterprises-A Combined Quantitative/Qualitative Study of Its Determinants from the Perspective of Enterprise Representatives.

The workplace is an ideal environment for promoting workers' health. Nevertheless, preventive health measures are insufficiently implemented, especially in small and medium-sized enterprises (SMEs) with up to 250 employees. The aim of this study was to investigate determinants for the implementation of measures to prevent musculoskeletal and mental health disorders from the perspective of enterprise representatives in Dutch SMEs. An online survey was completed by 79 SME representatives (e.g., owners, HR professionals and occupational health and safety officers) in the cleaning, care, construction and transport sectors. In addition, semi-structured interviews were conducted with 18 enterprise representatives. The interview transcripts were analyzed using an inductive approach. Survey data showed that the focus of prevention efforts by SMEs is on improving working conditions and complying with legally required occupational health requirements, while lifestyle measures are rarely implemented. The determinants of implementation according to enterprise representatives were associated with 10 distinct themes. These were (1) available resources (both finances and staff), (2) complexity of implementation of measures, (3) awareness, (4) knowledge and expertise, (5) availability of time, (6) employer and worker commitment, (7) workers' openness for measures, (8) communication, (9) workers' trust and autonomy and (10) integration in organizational policy. These findings can serve as a support for developing strategies for implementing preventive health measures in SMEs.

Acceptability, effectiveness and cost-effectiveness of blended cognitive-behavioural therapy (bCBT) versus face-to-face CBT (ftfCBT) for anxiety disorders in specialised mental health care: A 15-week randomised controlled trial with 1-year follow-up.

BACKGROUND: Anxiety disorders are highly prevalent and cause substantial economic burden. Blended cognitive-behavioural therapy (bCBT), which integrates Internet-based CBT and face-to-face CBT (ftfCBT), is an attractive and potentially cost-saving treatment alternative to conventional CBT for patients with anxiety disorders in specialised mental health care. However, little is known about the effectiveness of bCBT in routine care. We examined the acceptability, effectiveness and cost-effectiveness of bCBT versus ftfCBT in outpatient specialised care to patients with panic disorder, social anxiety disorder and generalised anxiety disorder. METHODS AND FINDINGS: Patients with anxiety disorders were randomised to bCBT (n = 52) or ftfCBT (n = 62). Acceptability of bCBT and ftfCBT were evaluated by assessing treatment preference, adherence, satisfaction and therapeutic alliance. Costs and effects were assessed at post-treatment and one-year follow-up. Primary outcome measure was the Beck Anxiety Inventory (BAI). Secondary outcomes were depressive symptoms, general psychopathology, work and social adjustment, quality of life and mastery. Incremental cost-effectiveness ratios (ICERs) were computed from societal and healthcare perspectives by calculating the incremental costs per incremental quality-adjusted life year (QALY). No significant differences between bCBT and ftfCBT were found on acceptability or effectiveness measures at post-treatment (Cohen's d between-group effect size on BAI = 0.15, 95% CI -0.30 to 0.60) or at one-year follow-up (d = -0.38, 95% CI -0.84 to 0.09). The modelled point estimates of societal costs (bCBT €10945, ftfCBT €10937) were higher and modelled point estimates of direct medical costs (bCBT €3748, ftfCBT €3841) were lower in bCBT. The acceptability curves showed that bCBT was expected to be a cost-effective intervention. Results should be carefully interpreted due to the small sample size. CONCLUSIONS: bCBT appears an acceptable, clinically effective and potentially cost-saving alternative option for treating patients with anxiety disorders. Trials with larger samples are needed to further investigate cost-effectiveness. TRIAL REGISTRATION: Netherlands Trial Register: NTR4912.

High-Speed Atomic Force Microscopy Visualization of the Dynamics of the Multienzyme Fatty Acid Synthase.

Multienzymes, such as the protein metazoan fatty acid synthase (FAS), are giant and highly dynamic molecular machines for critical biosynthetic processes. The molecular architecture of FAS was elucidated by static high-resolution crystallographic analysis, while electron microscopy revealed large-scale conformational variability in FAS with some correlation to functional states in catalysis. However, little is known about time scales of conformational dynamics, the trajectory of motions in individual FAS molecules, and the extent of coupling between catalysis and structural changes. Here, we present an experimental single-molecule approach to film immobilized or selectively tethered FAS in solution at different viewing angles and high spatiotemporal resolution using high-speed atomic force microscopy. Mobility of individual regions of the multienzyme is recognized in video sequences, and correlation of shape features implies a convergence of temporal resolution and velocity of FAS dynamics. Conformational variety can be identified and grouped by reference-free 2D class averaging, enabling the tracking of conformational transitions in movies. The approach presented here is suited for comprehensive studies of the dynamics of FAS and other multienzymes in aqueous solution at the single-molecule level.

Structural and Biochemical Analysis of a Single Amino-Acid Mutant of WzzBSF That Alters Lipopolysaccharide O-Antigen Chain Length in Shigella flexneri.

Lipopolysaccharide (LPS), a surface polymer of Gram-negative bacteria, helps bacteria survive in different environments and acts as a virulence determinant of host infection. The O-antigen (Oag) component of LPS exhibits a modal chain-length distribution that is controlled by polysaccharide co-polymerases (PCPs). The molecular basis of the regulation of Oag chain-lengths remains unclear, despite extensive mutagenesis and structural studies of PCPs from Escherichia coli and Shigella. Here, we identified a single mutation (A107P) of the Shigella flexneri WzzBSF, by a random mutagenesis approach, that causes a shortened Oag chain-length distribution in bacteria. We determined the crystal structures of the periplasmic domains of wild-type WzzBSF and the A107P mutant. Both structures form a highly similar open trimeric assembly in the crystals, and show a similar tendency to self-associate in solution. Binding studies by bio-layer interferometry reveal cooperative binding of very short (VS)-core-plus-O-antigen polysaccharide (COPS) to the periplasmic domains of both proteins, but with decreased affinity for the A107P mutant. Our studies reveal that subtle and localized structural differences in PCPs can have dramatic effects on LPS chain-length distribution in bacteria, for example by altering the affinity for the substrate, which supports the role of the structure of the growing Oag polymer in this process.