Structural basis for evolutionarily conserved interactions between TFIIS and Paf1C.

The elongation factor TFIIS interacts with Paf1C complex to facilitate processive transcription by Pol II. We here determined the crystal structure of the trypanosoma TFIIS LW domain in a complex with the LFG motif of Leo1, as well as the structures of apo-form TFIIS LW domains from trypanosoma, yeast and human. We revealed that all three TFIIS LW domains possess a conserved hydrophobic core that mediates their interactions with Leo1. Intriguingly, the structural study revealed that trypanosoma Leo1 binding induces the TFIIS LW domain to undergo a conformational change reflected in the length and orientation of α6 helix that is absent in the yeast and human counterparts. These differences explain the higher binding affinity of the TFIIS LW domain interacting with Leo1 in trypanosoma than in yeast and human, and indicate species-specific variations in the interactions. Importantly, the interactions between the TFIIS LW domain and an LFG motif of Leo1 were found to be critical for TFIIS to anchor the entire Paf1C complex. Thus, in addition to revealing a detailed structural basis for the TFIIS-Paf1C interaction, our studies also shed light on the origin and evolution of the roles of TFIIS and Paf1C complex in regulation of transcription elongation.

Resonance assignments of the PUB domain of the RNF31 protein.

E3 ubiquitin protein ligase RNF31 is present in human proteins and is involved in linear ubiquitin chain assembly complex (LUBAC) activity and cell growth. RNF31 is involved in ubiquitination, which is the post-translational modification of proteins. Ubiquitin molecules connect with amino acid residues of target proteins under the action of ubiquitin-activating enzyme E1, ubiquitin binding enzyme E2 and ubiquitin ligase E3, so as to achieve certain physiological functions. The abnormal expression of ubiquitination promotes the formation of cancer. In studies of breast cancer, RNF31 mRNA levels were found to be higher in cancer cells than in other tissues. The PUB domain of RNF31 is the binding site of the ubiquitin thioesterase otulin. Here, we report the backbone and side-chain resonance assignments of the PUB domain of RNF31 and study the backbone relaxation of the domain. These studies will contribute to further understanding of the structural and functional relationship of RNF31 protein, which may also be a target for drug research.

Associations of depression score with metabolic dysfunction-associated fatty liver disease and liver fibrosis.

BACKGROUND: Growing evidence suggests a link between depression and nonalcoholic fatty liver disease (NAFLD). Recently, a change from NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed. The aim of this study was to determine whether depression scores are associated with newly defined MAFLD as well as liver fibrosis in the US general population. METHODS: This cross-sectional study utilized data from the 2017-March 2020 cycle of the National Health and Nutrition Examination Survey (NHANES) in the US. The depression score was assessed with the Patient Health Questionnaire-9 (PHQ-9). Transient elastography was utilized to evaluate hepatic steatosis and fibrosis with controlled attenuation parameters and liver stiffness measurements, respectively. All the analyses accounted for the complex design parameters and sampling weights of the survey. RESULTS: A total of 3263 eligible subjects aged 20 years and older were included. The estimated prevalence of mild and major depression was 17.0 % (95 % confidence interval [CI]: 14.8-19.3 %) and 7.1 % (6.1-8.1 %), respectively. For every one-unit increase in depression score, a subject was 1.05 (1.02-1.08) times more likely to have MAFLD. Compared to the minimal depression group, those with mild depression had an odds ratio (OR) of 1.54 (1.06-2.25) for MAFLD. The depression score was not associated with clinically significant liver fibrosis. CONCLUSION: The depression score measured by PHQ-9 was independently associated with MAFLD among US adults. LIMITATIONS: Causal relationship is not available due to the cross-sectional nature of the survey design.

Deafness-Associated ADGRV1 Mutation Impairs USH2A Stability through Improper Phosphorylation of WHRN and WDSUB1 Recruitment.

The ankle-link complex (ALC) consists of USH2A, WHRN, PDZD7, and ADGRV1 and plays an important role in hair cell development. At present, its architectural organization and signaling role remain unclear. By establishing Adgrv1 Y6236fsX1 mutant mice as a model of the deafness-associated human Y6244fsX1 mutation, the authors show here that the Y6236fsX1 mutation disrupts the interaction between adhesion G protein-coupled receptor V subfamily member 1 (ADGRV1) and other ALC components, resulting in stereocilia disorganization and mechanoelectrical transduction (MET) deficits. Importantly, ADGRV1 inhibits WHRN phosphorylation through regional cAMP-PKA signaling, which in turn regulates the ubiquitination and stability of USH2A via local signaling compartmentalization, whereas ADGRV1 Y6236fsX1 does not. Yeast two-hybrid screening identified the E3 ligase WDSUB1 that binds to WHRN and regulates the ubiquitination of USH2A in a WHRN phosphorylation-dependent manner. Further FlAsH-BRET assay, NMR spectrometry, and mutagenesis analysis provided insights into the architectural organization of ALC and interaction motifs at single-residue resolution. In conclusion, the present data suggest that ALC organization and accompanying local signal transduction play important roles in regulating the stability of the ALC.

Review of the epidemiology, pathogenesis and prevention of atrial fibrillation after pacemaker implantation.

Cardiac pacemaker implantation is an important treatment for symptomatic bradycardia. However, epidemiological data show that the incidence of atrial fibrillation (AF) is significantly higher in patients with implanted pacemakers than in the general population, which may be related to the preoperative presence of multiple risk factors for AF, improvement of diagnostic sensitivity and the pacemaker itself. The pathogenesis of AF after the implantation of pacemaker is related to cardiac electrical remodeling, structural remodeling, inflammation, and autonomic nervous disorder, which are induced by the pacemaker. Moreover, different pacing modes and pacing sites have various effects on the pathogenesis of postoperative AF. Recent studies have reported that reducing the proportion of ventricular pacing, improving the pacing site and setting up special pacing procedures might be highly useful in prevention of AF after pacemaker implantation. This article reviews the epidemiology, pathogenesis, influencing factors, and preventive measures regarding AF after pacemaker surgery.

Two Binding Sites of SARS-CoV-2 Macrodomain 3 Probed by Oxaprozin and Meclomen.

Severe acute respiratory syndrome-coronavirus-1/2 (SARS-CoV-1/2) macrodomain 3 (Mac3) is critical for replication and transcription of the viral genome and is therefore a potential therapeutic target. Here, we solved the crystal structure of SARS-CoV-2 Mac3, which reveals a small-molecule binding pocket. Two low-molecular-weight drugs, oxaprozin and meclomen, induced different patterns of nuclear magnetic resonance (NMR) chemical shift perturbations (CSPs). Meclomen binds to site I of SARS-CoV-2 Mac3 with binding pose determined by NMR CSP and transferred paramagnetic relaxation enhancement, while oxaprozin binds to site II as revealed by the crystal structure. Interestingly, oxaprozin and meclomen both perturb residues in site I of SARS-CoV Mac3. Fluorescence polarization experiments further demonstrated that oxaprozin and meclomen inhibited the binding of DNA-G4s to SARS-CoV-2 Mac3. Our work identified two adjacent ligand-binding sites of SARS-CoV-2 Mac3 that shall facilitate structure-guided fragment linking of these compounds for more potent inhibitors.

Successful transcatheter arterial embolization treatment for chest wall haematoma following permanent pacemaker implantation: A case report.

BACKGROUND: Haematoma is one of the main complications associated with pacemaker implantation. Pseudoaneurysm is a rare condition that is not easy to identify and is often overlooked. CASE SUMMARY: A female patient diagnosed with high-grade atrioventricular block underwent permanent pacemaker implantation. During the operation, puncturing a small branch of the right subclavian artery developed into a pseudoaneurysm and resulted in further haematoma formation. Conventional treatment of compression haemostasis and haemostatic drugs was not effective. A series of timely transcatheter arterial embolizations avoided serious complications. CONCLUSION: More possible conditions should be taken into consideration as haematoma is discovered, and timely treatment might prevent severe adverse events.

Resonance assignments of the ORC2-WH domain of the human ORC protein.

ORC2 is a small subunit of the origin recognition complex (ORC), which is important for gene replication. The ORC2 WH domain recognizes dsDNA sequences with its flexible ß-sheet hairpins as anchors. Here, we report near-complete NMR backbone and side chain resonance assignments of the WH domain and study the backbone relaxation of the WH domain. These studies will contribute to further understanding of the structure-function relationship of the ORC protein.

1H, 13C and 15N resonance assignments of TbBDF5-bromo1 domain from Trypanosoma brucei.

1H, 13C and 15N resonance assignments are presented for the first bromo domain of TbBDF5 (TbBDF5-bromo1) from Trypanosoma brucei. TbBDF5 is localized in the nucleus and plays a potential role in transcription regulation. Bromo domains can recognize acetylated histone through a conserved binding pocket. Here we report the NMR resonance assignments of TbBDF5-bromo1 domain for further studies of the relationship between its structure and function.

1H, 13C and 15N resonance assignments of stress granule key component G3BP1 RRM domain.

G3BP1 exists as a helicase and one of the core components in stress granules, which are associated with a variety of neurodegenerative diseases. Its RNA recognition motif (RRM) domain performs the paramount function of binding mRNA. Here we report the resonance assignment of human G3BP1 RRM domain to understand its structure-function relationship.

5-min mindfulness audio induction alleviates psychological distress and sleep disorders in patients with COVID-19.

BACKGROUND: Mindfulness meditation is beneficial to mitigate the negative effects of the coronavirus disease 2019 (COVID-19) pandemic in the general population, but no study examined such meditation in the COVID-19 patients themselves. AIM: To explore the short-term efficacy of mindfulness meditation in alleviating psychological distress and sleep disorders in patients with COVID-19. METHODS: This prospective study enrolled patients with mild COVID-19 treated at Wuhan Fangcang Hospital in February 2020. The patients were voluntarily divided into either a mindfulness or a conventional intervention group. The patients were evaluated before/after the intervention using the Short Inventory of Mindfulness Capability (SMI-C), Hospital Anxiety and Depression Scale (HADS), and Pittsburgh Sleep Quality Index (PSQI). RESULTS: Seventy-five participants were enrolled in this study, with 43 and 32 in the mindfulness and conventional groups, respectively. Before the intervention, there were no differences in SMI-C, HADS, or PSQI scores between the two groups. After the 2-wk intervention, the mindfulness level (from 30.16 ± 5.58 to 35.23 ± 5.95, P < 0.001) and sleep quality (from 12.85 ± 3.06 to 9.44 ± 3.86, P < 0.001) were significantly increased in the mindfulness group. There were no differences in the conventional group. After the intervention, the mindfulness level (35.23 ± 5.95 vs 31.17 ± 6.50, P = 0.006) and sleep quality (9.44 ± 3.86 vs 11.87 ± 4.06, P = 0.011) were significantly higher in the mindfulness group than in the conventional group. Depression decreased in the mindfulness group (from 14.15 ± 3.21 to 12.50 ± 4.01, P = 0.038), but there was no difference between the two groups. CONCLUSION: Short-term mindfulness meditation can increase the mindfulness level, improve the sleep quality, and decrease the depression of patients with COVID-19.

1H, 13C and 15N resonance assignments of TFIIS LW domain from Saccharomyces cerevisiae.

TFIIS is one of the best-characterized transcription elongation factors, with a domain I (named also as LW domain) in the N-terminus. It can relieve the arrest of RNA polymerase II (RNAP II) when the elongation of RNAP II is impaired. Here we report the resonance assignments of the protein backbone and side chains of the LW domain of TFIIS from S. cerevisiae, the secondary structure prediction indicates the ScTFIIS LW domain contains six α-helices with no ß-sheet, which will lay the foundation for the protein structure determination and function elucidation.

Driving force of biomolecular liquid-liquid phase separation probed by nuclear magnetic resonance spectroscopy.

The assembly of biomolecular condensates is driven by liquid-liquid phase separation. To understand the structure and functions of these condensates, it is essential to characterize the underlying driving forces, e.g., protein-protein and protein-RNA interactions. As both structured and low-complexity domains are involved in the phase separation process, NMR is probably the only technique that can be used to depict the binding topology and interaction modes for the structured and nonstructured domains simultaneously. Atomic-resolution analysis for the intramolecular and intermolecular interactions between any pair of components sheds light on the mechanism for phase separation and biomolecular condensate assembly and disassembly. Herein, we describe the procedures used for the most extensively employed NMR techniques to characterize key interactions for biomolecular phase separation.

Blood Donation Fear, Perceived Rewards, Self-Efficacy, and Intention to Return Among Whole Blood Donors in China: A Social Cognitive Perspective.

With the increasing demand from aging population and seasonal blood shortage, recruiting and retaining blood donors has become an urgent issue for the blood collection centers in China. This study aims to understand intention to donate again from a social cognitive perspective among whole blood donors in China through investigating the association between the blood donation fear, perceived rewards, self-efficacy, and intention to return. A cross-sectional survey was conducted in six cities, which are geographically and socioeconomically distinct areas in Jiangsu, China. Respondents completed a self-administrated questionnaire interviewed by two well-trained medical students. A total of 191 blood donors were included in the current study. Descriptive analysis, correlation analysis, and a generalized linear regression model were used to explore the association between demographic characteristics, psychological factors, and intention to donate again. After controlling other covariates, donors with higher fear scores reported lower intention to return (p = 0.008). Association between self-efficacy and intention to return was statistically significant (p < 0.001), whereas the association between intrinsic rewards (p = 0.387), extrinsic rewards (p = 0.939), and intention to return were statistically insignificant. This study found that either intrinsic rewards or extrinsic rewards are not significantly associated with intention to donate again among whole blood donors in China, and fear is negatively associated with intention to donate again. Therefore, purposive strategies could be enacted beyond appeals to rewards and focus on the management of donors' fear.

The Role of Short-Chain Fatty Acids of Gut Microbiota Origin in Hypertension.

Hypertension is a significant risk factor for cardiovascular and cerebrovascular diseases, and its development involves multiple mechanisms. Gut microbiota has been reported to be closely linked to hypertension. Short-chain fatty acids (SCFAs)-the metabolites of gut microbiota-participate in hypertension development through various pathways, including specific receptors, immune system, autonomic nervous system, metabolic regulation and gene transcription. This article reviews the possible mechanisms of SCFAs in regulating blood pressure and the prospects of SCFAs as a target to prevent and treat hypertension.

Molecular basis for PICS-mediated piRNA biogenesis and cell division.

By incorporating two mutually exclusive factors, PID-1 and TOST-1, C. elegans PICS complex plays important roles in piRNA biogenesis, chromosome segregation and cell division. We firstly map the interaction network between PICS subunits, then uncover the mechanisms underlying the interactions between PICS subunits by solving several complex structures, including those of TOFU-6/PICS-1, ERH-2/PICS-1, and ERH-2/TOST-1. Our biochemical experiment also demonstrates that PICS exists as an octamer consisting of two copies of each subunit. Combining structural analyses with mutagenesis experiments, we identify interfacial residues of PICS subunits that are critical for maintaining intact PICS complex in vitro. Furthermore, using genetics, cell biology and imaging experiments, we find that those mutants impairing the in vitro interaction network within PICS, also lead to dysfunction of PICS in vivo, including mislocalization of PICS, and reduced levels of piRNAs or aberrant chromosome segregation and cell division. Therefore, our work provides structural insights into understanding the PICS-mediated piRNA biogenesis and cell division.

Crystal structure of TbAlba1 from Trypanosoma brucei.

Alba (Acetylation lowers binding affinity) domain is a small, dimeric nucleic acid-binding domain, which is widely distributed in archaea and numbers of eukaryotes. Alba domain containing proteins have been reported to be involved in many cellular processes, such as regulation of translation, maintaining genome stability, regulation of RNA processing and so on. In Trypanosoma brucei (T. brucei), there are four Alba proteins identified, which are named TbAlba1 to TbAlba4. However, the structure and function of TbAlba proteins are still unknown. Here, we solved the crystal structure of TbAlba1 to a resolution of 2.46 Å. TbAlba1 adopts a similar Alba-fold, which comprises of four ß-strands (ß1-ß4) and three long α-helices (α1-α3). Furthermore, TbAlba1 displays some structural features quite different from other Alba proteins. These differences may imply the diverse biological roles of Alba family members.

Molecular basis for arginine C-terminal degron recognition by Cul2FEM1 E3 ligase.

Degrons are elements within protein substrates that mediate the interaction with specific degradation machineries to control proteolysis. Recently, a few classes of C-terminal degrons (C-degrons) that are recognized by dedicated cullin-RING ligases (CRLs) have been identified. Specifically, CRL2 using the related substrate adapters FEM1A/B/C was found to recognize C degrons ending with arginine (Arg/C-degron). Here, we uncover the molecular mechanism of Arg/C-degron recognition by solving a subset of structures of FEM1 proteins in complex with Arg/C-degron-bearing substrates. Our structural research, complemented by binding assays and global protein stability (GPS) analyses, demonstrates that FEM1A/C and FEM1B selectively target distinct classes of Arg/C-degrons. Overall, our study not only sheds light on the molecular mechanism underlying Arg/C-degron recognition for precise control of substrate turnover, but also provides valuable information for development of chemical probes for selectively regulating proteostasis.

Halophilic to mesophilic adaptation of ubiquitin-like proteins.

Elucidating how proteins adapt from halophilic to mesophilic environments will enable a better understanding of protein evolution and folding. In this study, by directed evolution and site-directed mutagenesis of the halophilic ubiquitin-like protein (ULP) Samp2, we find that substitution of the prebiotic amino acid Asp31 by Gly is uniquely effective in the mesophilic adaptation of ULP. Sequence analysis shows that substitution of Asp/Glu in halophilic ULPs by Gly in mesophilic ULPs has higher occurrence than other substitutions, supporting the unique role of the substitution in the mesophilic adaptation of ULP. Molecular dynamic simulations indicate that the mesophilic adaptation might result from the effect of the substitution on the conformational flexibility of ULP.