The Listeria monocytogenes persistence factor ClpL is a potent stand-alone disaggregase

Heat stress can cause cell death by triggering the aggregation of essential proteins. In bacteria, aggregated proteins are rescued by the canonical Hsp70/AAA+ (ClpB) bi-chaperone disaggregase. Man-made, severe stress conditions applied during, e.g., food processing represent a novel threat for bacteria by exceeding the capacity of the Hsp70/ClpB system. Here, we report on the potent autonomous AAA+ disaggregase ClpL from Listeria monocytogenes that provides enhanced heat resistance to the food-borne pathogen enabling persistence in adverse environments. ClpL shows increased thermal stability and enhanced disaggregation power compared to Hsp70/ClpB, enabling it to withstand severe heat stress and to solubilize tight aggregates. ClpL binds to protein aggregates via aromatic residues present in its N-terminal domain (NTD) that adopts a partially folded and dynamic conformation. Target specificity is achieved by simultaneous interactions of multiple NTDs with the aggregate surface. ClpL shows remarkable structural plasticity by forming diverse higher assembly states through interacting ClpL rings. NTDs become largely sequestered upon ClpL ring interactions. Stabilizing ring assemblies by engineered disulfide bonds strongly reduces disaggregation activity, suggesting that they represent storage states.

Tropomyosin 1-I/C coordinates kinesin-1 and dynein motors during oskar mRNA transport

Dynein and kinesin motors mediate long-range intracellular transport, translocating towards microtubule minus and plus ends, respectively. Cargoes often undergo bidirectional transport by binding to both motors simultaneously. However, it is not known how motor activities are coordinated in such circumstances. In the Drosophila female germline, sequential activities of the dynein-dynactin-BicD-Egalitarian (DDBE) complex and of kinesin-1 deliver oskar messenger RNA from nurse cells to the oocyte, and within the oocyte to the posterior pole. We show through in vitro reconstitution that Tm1-I/C, a tropomyosin-1 isoform, links kinesin-1 in a strongly inhibited state to DDBE-associated oskar mRNA. Nuclear magnetic resonance spectroscopy, small-angle X-ray scattering and structural modeling indicate that Tm1-I/C suppresses kinesin-1 activity by stabilizing its autoinhibited conformation, thus preventing competition with dynein until kinesin-1 is activated in the oocyte. Our work reveals a new strategy for ensuring sequential activity of microtubule motors.

Structural basis of aggregate binding by the AAA+ disaggregase ClpG

Severe heat stress causes massive loss of essential proteins by aggregation, necessitating a cellular activity that rescues aggregated proteins. This activity is executed by ATP-dependent, ring-forming, hexameric AAA+ disaggregases. Little is known about the recognition principles of stress-induced protein aggregates. How can disaggregases specifically target aggregated proteins, while avoiding binding to soluble non-native proteins? Here, we determined by NMR spectroscopy the core structure of the aggregate-targeting N1 domain of the bacterial AAA+ disaggregase ClpG, which confers extreme heat resistance to bacteria. N1 harbors a Zn2+-coordination site that is crucial for structural integrity and disaggregase functionality. We found that conserved hydrophobic N1 residues located on a β-strand are crucial for aggregate targeting and disaggregation activity. Analysis of mixed hexamers consisting of full-length and N1-truncated subunits revealed that a minimal number of four N1 domains must be present in a AAA+ ring for high-disaggregation activity. We suggest that multiple N1 domains increase substrate affinity through avidity effects. These findings define the recognition principle of a protein aggregate by a disaggregase, involving simultaneous contacts with multiple hydrophobic substrate patches located in close vicinity on an aggregate surface. This binding mode ensures selectivity for aggregated proteins while sparing soluble, non-native protein structures from disaggregase activity.

Confessions of a hedgehog aspirant: Reply to Verkuyten (2023) and Jung (2023)

The potential of the disapproval-respect model as a conceptual tool and explanatory device for the analysis of tolerance phenomena as well as its value as a guideline for future tolerance research is reiterated and further explained. Also, the distinctiveness of the model is underscored as is its realism with regard to the role of tolerance in processes of social influence and social change. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Taking tolerance seriously: A proposal from a self-categorization perspective on disapproval and respect

A dual-level disapproval-respect model of tolerance is proposed, and its social psychological foundations are explicated from a self-categorization perspective. The model specifies tolerance as the combination of disapproval of others' beliefs, practices, or ways of life, which results from self-categorization at the level of in-group-out-group differentiation (Level 1), and respect, which is grounded in shared group membership at a higher level of self-categorization and the resulting superordinate identity (Level 2) and operates as a restraining force. In short, tolerance is disapproval restrained by respect, or, put differently, respect burdened with disapproval. Drawing on pertinent empirical evidence, it is argued that such tolerance is realistic and practicable in that people are willing to practice it and, when they are the recipients, likely to appreciate it. The model throws new light on the roles of affect and cognition in tolerance, on the interrelation of tolerance, authenticity, and dignity, as well as the interrelation of tolerance, justice, and struggles for social change, and on the limits of tolerance. The examination of these issues from the perspective of the disapproval-respect model makes the social psychological, moral, and political dimensions of tolerance explicit and clarifies their interrelations. Finally, directions for future basic as well as applied research on tolerance as specified in the model are suggested, and broader sociocultural implications of taking such tolerance seriously are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Energy-Efficient Decentralized Broadcasting in Wireless Multi-Hop Networks

Several areas of wireless networking, such as wireless sensor networks or the Internet of Things, require application data to be distributed to multiple receivers in an area beyond the transmission range of a single node. This can be achieved by using the wireless medium's broadcast property when retransmitting data. Due to the energy constraints of typical wireless devices, a broadcasting scheme that consumes as little energy as possible is highly desirable. In this article, we present a novel multi-hop data dissemination protocol called BTP. It uses a game-theoretical model to construct a spanning tree in a decentralized manner to minimize the total energy consumption of a network by minimizing the transmission power of each node. Although BTP is based on a game-theoretical model, it neither requires information exchange between distant nodes nor time synchronization during its operation, and it inhibits graph cycles effectively. The protocol is evaluated in Matlab and NS-3 simulations and through real-world implementation on a testbed of 75 Raspberry Pis. The evaluation conducted shows that our proposed protocol can achieve a total energy reduction of up to 90% compared to a simple broadcast protocol in real-world experiments.

Structural basis for specific RNA recognition by the alternative splicing factor RBM5

The RNA-binding motif protein RBM5 belongs to a family of multi-domain RNA binding proteins that regulate alternative splicing of genes important for apoptosis and cell proliferation and have been implicated in cancer. RBM5 harbors structural modules for RNA recognition, such as RRM domains and a Zn finger, and protein-protein interactions such as an OCRE domain. Here, we characterize binding of the RBM5 RRM1-ZnF1-RRM2 domains to cis-regulatory RNA elements. A structure of the RRM1-ZnF1 region in complex with RNA shows how the tandem domains cooperate to sandwich target RNA and specifically recognize a GG dinucleotide in a non-canonical fashion. While the RRM1-ZnF1 domains act as a single structural module, RRM2 is connected by a flexible linker and tumbles independently. However, all three domains participate in RNA binding and adopt a closed architecture upon RNA binding. Our data highlight how cooperativity and conformational modularity of multiple RNA binding domains enable the recognition of distinct RNA motifs, thereby contributing to the regulation of alternative splicing. Remarkably, we observe surprising differences in coupling of the RNA binding domains between the closely related homologs RBM5 and RBM10.

Novel UL23 and UL30 substitutions in HSV1 and HSV2 viruses related to polymorphism or drug resistance

Data on herpes simplex virus (HSV) polymorphism as well as acyclovir (ACV) and foscarnet (FOS) resistance mutations are not exhaustive and may hinder accurate diagnosis by next-generation sequencing (NGS). Here, we report novel UL23 and UL30 substitutions for HSV1 and HSV2 identified in immunocompromised patients treated for hematological malignancies during the last 6 years of HSV resistance surveillance at the University Hospital of Lyon. For HSV1, 35 novel UL23 substitutions and 52 novel UL30 substitutions were identified. For HSV2, 2 novel UL23 substitutions and 12 novel UL30 substitutions were identified. These results allow to complete the database of HSV1 and HSV2 substitutions, related either to polymorphism or to ACV and FOS resistance.

Upstream of N-Ras C-terminal cold shock domains mediate poly(A) specificity in a novel RNA recognition mode and bind poly(A) binding protein

RNA binding proteins (RBPs) often engage multiple RNA binding domains (RBDs) to increase target specificity and affinity. However, the complexity of target recognition of multiple RBDs remains largely unexplored. Here we use Upstream of N-Ras (Unr), a multidomain RBP, to demonstrate how multiple RBDs orchestrate target specificity. A crystal structure of the three C-terminal RNA binding cold-shock domains (CSD) of Unr bound to a poly(A) sequence exemplifies how recognition goes beyond the classical ππ-stacking in CSDs. Further structural studies reveal several interaction surfaces between the N-terminal and C-terminal part of Unr with the poly(A)-binding protein (pAbp). All interactions are validated by mutational analyses and the high-resolution structures presented here will guide further studies to understand how both proteins act together in cellular processes.

Mechanistic insights into RNA surveillance by the canonical poly(A) polymerase Pla1 of the MTREC complex

The S. pombe orthologue of the human PAXT connection, Mtl1-Red1 Core (MTREC), is an eleven-subunit complex that targets cryptic unstable transcripts (CUTs) to the nuclear RNA exosome for degradation. It encompasses the canonical poly(A) polymerase Pla1, responsible for polyadenylation of nascent RNA transcripts as part of the cleavage and polyadenylation factor (CPF/CPSF). In this study we identify and characterise the interaction between Pla1 and the MTREC complex core component Red1 and analyse the functional relevance of this interaction in vivo. Our crystal structure of the Pla1-Red1 complex shows that a 58-residue fragment in Red1 binds to the RNA recognition motif domain of Pla1 and tethers it to the MTREC complex. Structure-based Pla1-Red1 interaction mutations show that Pla1, as part of MTREC complex, hyper-adenylates CUTs for their efficient degradation. Interestingly, the Red1-Pla1 interaction is also required for the efficient assembly of the fission yeast facultative heterochromatic islands. Together, our data suggest a complex interplay between the RNA surveillance and 3'-end processing machineries.

Structure and dynamics of the von Willebrand Factor C6 domain

Von Willebrand disease (VWD) is a bleeding disorder with different levels of severity. VWD-associated mutations are located in the von Willebrand factor (VWF) gene, coding for the large multidomain plasma protein VWF with essential roles in hemostasis and thrombosis. On the one hand, a variety of mutations in the C-domains of VWF are associated with increased bleeding upon vascular injury. On the other hand, VWF gain-of-function (GOF) mutations in the C4 domain have recently been identified, which induce an increased risk of myocardial infarction. Mechanistic insights into how these mutations affect the molecular behavior of VWF are scarce and holistic approaches are challenging due to the multidomain and multimeric character of this large protein. Here, we determine the structure and dynamics of the C6 domain and the single nucleotide polymorphism (SNP) variant G2705R in C6 by combining nuclear magnetic resonance spectroscopy, molecular dynamics simulations and aggregometry. Our findings indicate that this mutation mostly destabilizes VWF by leading to a more pronounced hinging between both subdomains of C6. Hemostatic parameters of variant G2705R are close to normal under static conditions, but the missense mutation results in a gain-of-function under flow conditions, due to decreased VWF stem stability. Together with the fact that two C4 variants also exhibit GOF characteristics, our data underline the importance of the VWF stem region in VWF's hemostatic activity and the risk of mutation-associated prothrombotic properties in VWF C-domain variants due to altered stem dynamics.

The meaning of respect under varying context conditions

The concept of respect figures prominently in several theories on intergroup relations. Previous studies suggested that the experience of being respected is primarily related to the feeling of being recognized as an equal, as opposed to social recognition of needs or achievements. Those studies focused, however, on either minority groups or ad hoc groups, thereby possibly giving equality recognition an advantage. This article extends previous findings by comparing societal groups situated in various contexts. We examined eight groups from four countries. We anticipated and found that the link between respect and equality recognition was stronger for groups that are in the position of minorities compared to groups associated with majorities. Owing to the moral and legal force of the norm of equality, disadvantaged minorities in particular might be able to improve their societal position by founding their claims on the equality principle. Need recognition, in contrast, was less influential for minority groups than for majority groups. While we observed these context-dependent variations, an internal meta-analysis showed that feeling recognized as an equal was, overall, the strongest indicator for feeling respected. This suggests that demands for respect could often be addressed by establishing relationships in society that are based on mutual recognition as equals, while the implications of achievement and need recognition should additionally be considered in specific contexts.

Titin kinase ubiquitination aligns autophagy receptors with mechanical signals in the sarcomere

Striated muscle undergoes remodelling in response to mechanical and physiological stress, but little is known about the integration of such varied signals in the myofibril. The interaction of the elastic kinase region from sarcomeric titin (A168-M1) with the autophagy receptors Nbr1/p62 and MuRF E3 ubiquitin ligases is well suited to link mechanosensing with the trophic response of the myofibril. To investigate the mechanisms of signal cross-talk at this titin node, we elucidated its 3D structure, analysed its response to stretch using steered molecular dynamics simulations and explored its functional relation to MuRF1 and Nbr1/p62 using cellular assays. We found that MuRF1-mediated ubiquitination of titin kinase promotes its scaffolding of Nbr1/p62 and that the process can be dynamically down-regulated by the mechanical unfolding of a linker sequence joining titin kinase with the MuRF1 receptor site in titin. We propose that titin ubiquitination is sensitive to the mechanical state of the sarcomere, the regulation of sarcomere targeting by Nbr1/p62 being a functional outcome. We conclude that MuRF1/Titin Kinase/Nbr1/p62 constitutes a distinct assembly that predictably promotes sarcomere breakdown in inactive muscle.

Structural basis of PETISCO complex assembly during piRNA biogenesis in C. elegans

In this study, Perez-Borrajero et al. set out to characterize PETISCO architecture and its interaction with RNA, together with its effector proteins TOST-1 and PID-1. Using biochemical and structural biology approaches, the authors found that PETISCO forms a dimer of tetramers, in which dimerization is mediated by both PID-3 and ERH-2. Crystal structures of the PID- 3/TOFU-6 and ERH-2/PID-3 subcomplexes reveal insights into PETISCO assembly, function, and subcellular localization. Using NMR spectroscopy, the authors also characterize the mutually exclusive interplay of ERH-2 with the two effector proteins TOST-1 and PID-1.

Piwi-interacting RNAs (piRNAs) constitute a class of small RNAs that bind PIWI proteins and are essential to repress transposable elements in the animal germline, thereby promoting genome stability and maintaining fertility. C. elegans piRNAs (21U RNAs) are transcribed individually from minigenes as precursors that require 5′ and 3′ processing. This process depends on the PETISCO complex, consisting of four proteins: IFE-3, TOFU-6, PID-3, and ERH-2. We used biochemical and structural biology approaches to characterize the PETISCO architecture and its interaction with RNA, together with its effector proteins TOST-1 and PID-1. These two proteins define different PETISCO functions: PID-1 governs 21U processing, whereas TOST-1 links PETISCO to an unknown process essential for early embryogenesis. Here, we show that PETISCO forms an octameric assembly with each subunit present in two copies. Determination of structures of the TOFU-6/PID-3 and PID-3/ERH-2 subcomplexes, supported by in vivo studies of subunit interaction mutants, allows us to propose a model for the formation of the TOFU-6/PID-3/ERH-2 core complex and its functionality in germ cells and early embryos. Using NMR spectroscopy, we demonstrate that TOST-1 and PID-1 bind to a common surface on ERH-2, located opposite its PID-3 binding site, explaining how PETISCO can mediate different cellular roles.

Bioaccumulation of therapeutic drugs by human gut bacteria

Bacteria in the gut can modulate the availability and efficacy of therapeutic drugs. However, the systematic mapping of the interactions between drugs and bacteria has only started recently¹ and the main underlying mechanism proposed is the chemical transformation of drugs by microorganisms (biotransformation). Here we investigated the depletion of 15 structurally diverse drugs by 25 representative strains of gut bacteria. This revealed 70 bacteria-drug interactions, 29 of which had not to our knowledge been reported before. Over half of the new interactions can be ascribed to bioaccumulation; that is, bacteria storing the drug intracellularly without chemically modifying it, and in most cases without the growth of the bacteria being affected. As a case in point, we studied the molecular basis of bioaccumulation of the widely used antidepressant duloxetine by using click chemistry, thermal proteome profiling and metabolomics. We find that duloxetine binds to several metabolic enzymes and changes the metabolite secretion of the respective bacteria. When tested in a defined microbial community of accumulators and non-accumulators, duloxetine markedly altered the composition of the community through metabolic cross-feeding. We further validated our findings in an animal model, showing that bioaccumulating bacteria attenuate the behavioural response of Caenorhabditis elegans to duloxetine. Together, our results show that bioaccumulation by gut bacteria may be a common mechanism that alters drug availability and bacterial metabolism, with implications for microbiota composition, pharmacokinetics, side effects and drug responses, probably in an individual manner.

Structure and dynamics of the quaternary hunchback mRNA translation repression complex

A key regulatory process during Drosophila development is the localized suppression of the hunchback mRNA translation at the posterior, which gives rise to a hunchback gradient governing the formation of the anterior-posterior body axis. This suppression is achieved by a concerted action of Brain Tumour (Brat), Pumilio (Pum) and Nanos. Each protein is necessary for proper Drosophila development. The RNA contacts have been elucidated for the proteins individually in several atomic-resolution structures. However, the interplay of all three proteins during RNA suppression remains a long-standing open question. Here, we characterize the quaternary complex of the RNA-binding domains of Brat, Pum and Nanos with hunchback mRNA by combining NMR spectroscopy, SANS/SAXS, XL/MS with MD simulations and ITC assays. The quaternary hunchback mRNA suppression complex comprising the RNA binding domains is flexible with unoccupied nucleotides functioning as a flexible linker between the Brat and Pum-Nanos moieties of the complex. Moreover, the presence of the Pum-HD/Nanos-ZnF complex has no effect on the equilibrium RNA binding affinity of the Brat RNA binding domain. This is in accordance with previous studies, which showed that Brat can suppress mRNA independently and is distributed uniformly throughout the embryo.

Does Respect Foster Tolerance? (Re)analyzing and Synthesizing Data From a Large Research Project Using Meta-Analytic Techniques

Our own prior research has demonstrated that respect for disapproved others predicts and might foster tolerance toward them. This means that without giving up their disapproval of others' way of life, people can tolerate others when they respect them as equals (outgroup respect-tolerance hypothesis). Still, there was considerable variation in the study features. Moreover, the studies are part of a larger research project that affords many additional tests of our hypothesis. To achieve integration along with a more robust understanding of the relation between respect and tolerance, we (re)analyzed all existing data from this project, and we synthesized the results with the help of meta-analytic techniques. The average standardized regression coefficient, which describes the relationship between respect and tolerance, was 0.25 (95% confidence interval [CI] = [0.16, 0.34]). In addition to this overall confirmation of our hypothesis, the size of this coefficient varied with a number of variables. It was larger for numerical majorities than for minorities, smaller for high-status than for low-status groups, and larger for religious than for life-style groups. These findings should inspire further theory development and spur growth in the social-psychological literature on tolerance.

AB0051 THE EFFECTS OF NON-INVASIVE VAGUS NERVE STIMULATION ON IMMUNOLOGICAL RESPONSES AND PATIENT REPORTED OUTCOME MEASURES OF FATIGUE IN PATIENTS WITH CHRONIC FATIGUE SYNDROME, FIBROMYALGIA, AND RHEUMATOID ARTHRITIS

Background:

Fatigue is reported as a common symptom among autoimmune and other chronic diseases such as fibromyalgia (FM), a long-term condition with uncertain pathophysiology. Previous studies from our group suggest that non-invasive vagus nerve stimulation (nVNS) may contribute to the improvement of patient reported outcome measures (PROMs) of fatigue in patients with primary Sjögren’s Syndrome (1).

Objectives:

This follow-up study uses the gammaCore device (electroCore) to assess the effect of nVNS on PROMs of fatigue and immune responses in chronic fatigue syndrome (CFS), FM and rheumatoid arthritis (RA).

Methods:

The study included thirteen CFS, fourteen FM and fifteen RA patients who used the gammaCore nVNS device twice daily over a 26-day period. Pre- and post- nVNS bloods were drawn at baseline and final visits. Whole blood samples were stimulated with 2 ng/mL lipopolysaccharide (LPS) and the IL-6 and TNF-α cytokine concentrations were quantified at 24 hours. In addition, the epidermal growth factor (EGF), IFN-γ, IL-6, IP-10, MIP-1α, and TNF-α levels were measured in ‘pre-nVNS’ serum and flow cytometric profiles of whole blood immune cells were analysed. The patient reported outcome measures (PROMs) recorded at each visit were the Visual Analogue Scale (VAS) (0-100 cm) of abnormal fatigue, Hospital Anxiety and Depression (HAD) Scale, Orthostatic Grading Scale, Epworth Sleepiness Scale (daytime sleepiness), and Profile of fatigue (PRO-F) for Physical and Mental fatigue. Paired t-tests were performed to assess for changes in PROMs, cytokine levels, and cell subset distribution and associations of cytokine response with PROMs were investigated by correlation analyses.

Results:

Eleven CFS, twelve FM and fourteen RA patients completed the study. There was a significant reduction in daytime sleepiness in CFS (p =0.0321) and FM (p =0.0294) patients between the final and baseline visits and a significant reduction in HAD depression (p =0.0413) in FM (Fig.1). Improvement in VAS for abnormal fatigue, HAD-Anxiety, HAD-Depression, PRO-F Physical and Mental fatigue was observed in all three groups over the study period with a reduction in VAS fatigue in 64% of CFS, 67% of FM and 62% of RA patients. There were no significant changes in the immune cell subsets or in cytokine response. Finally, higher baseline pre-nVNS supernatant IL-6 levels were predictive of an improvement in VAS fatigue (p =0.0006), Daytime Sleepiness (p =0.0466) and PRO-F Physical fatigue (p =0.0196) in RA, while higher baseline TNF-α levels were predictive of an improvement in VAS fatigue (p =0.0003), Daytime Sleepiness (p =0.0380), Orthostatic (p =0.0281) and PRO-F Physical fatigue (p =0.0007) in FM.

Conclusion:

Our findings suggest that nVNS may contribute to the improvement of PROMs of fatigue in CFS, FM and RA. NVNS led to significant reductions in daytime sleepiness in CFS and FM, and depression in FM. Further studies and a larger sample size are needed to investigate the potential effects of nVNS on diseases characterised by persistent fatigue.

References:

[1]Tarn J, Legg S, Mitchell S, Simon B, Ng WF. The Effects of Noninvasive Vagus Nerve Stimulation on Fatigue and Immune Responses in Patients With Primary Sjögren’s Syndrome. Neuromodulation Technol Neural Interface. 2018;22(5):580–5.

Figure 1.

VAS for abnormal fatigue and PROMs recorded at baseline and final visits in patients with chronic fatigue syndrome (CFS), fibromyalgia (FM) and rheumatoid arthritis (RA). Boxplots show the median, upper, and lower quartiles for PROMs at visit 1 and visit 3 in each disease group. Paired-t tests revealed a significant reduction in daytime sleepiness in CFS and FM (B), and a significant reduction in HAD depression in FM (E). Improvement trends were observed in VAS for abnormal fatigue, HAD-Anxiety, HAD-Depression, PRO-F Physical fatigue and PRO-F Mental fatigue in all three groups over the 26-day study period.

Acknowledgements:

This study received infrastructural support from the National Institute of Health Research (NIHR) Newcastle Biomedical Research Centre at Newcastle Hospitals Foundation Trust and Newcastle University.

Disclosure of Interests:

Emmanuella Traianos: None declared, Bethany Dibnah: None declared, Dennis Lendrem: None declared, Yasmin Clark: None declared, Victoria Macrae: None declared, Victoria Slater: None declared, Karl Wood: None declared, David Storey: None declared, Bruce Simon Shareholder of: Bruce Simon is an employee and shareholder of electroCore., Employee of: electroCore, Inc., Justyna Blake Shareholder of: Justyna Blake is an employee of electroCore, and receives stock ownership., Employee of: electroCore, Inc., Jessica Tarn: None declared, Wan Fai Ng: None declared

Structural analysis of the SRP Alu domain from Plasmodium falciparum reveals a non-canonical open conformation

The eukaryotic signal recognition particle (SRP) contains an Alu domain, which docks into the factor binding site of translating ribosomes and confers translation retardation. The canonical Alu domain consists of the SRP9/14 protein heterodimer and a tRNA-like folded Alu RNA that adopts a strictly 'closed' conformation involving a loop-loop pseudoknot. Here, we study the structure of the Alu domain from Plasmodium falciparum (PfAlu), a divergent apicomplexan protozoan that causes human malaria. Using NMR, SAXS and cryo-EM analyses, we show that, in contrast to its prokaryotic and eukaryotic counterparts, the PfAlu domain adopts an 'open' Y-shaped conformation. We show that cytoplasmic P. falciparum ribosomes are non-discriminative and recognize both the open PfAlu and closed human Alu domains with nanomolar affinity. In contrast, human ribosomes do not provide high affinity binding sites for either of the Alu domains. Our analyses extend the structural database of Alu domains to the protozoan species and reveal species-specific differences in the recognition of SRP Alu domains by ribosomes.

Persistence and clearance of high-risk human papillomavirus and cervical dysplasia at 1 year in women living with human immunodeficiency virus: a prospective cohort study

OBJECTIVE

Evaluate 1-year outcomes of cervical cancer screening and treatment using primary high-risk human papillomavirus (HPV) testing in women living with human immunodeficiency virus (HIV).

DESIGN

Prospective cohort study.

SETTING

HIV treatment centre in Botswana.

POPULATION

Women living with HIV.

METHODS

Participants underwent cervical cancer screening with high-risk HPV testing and triage evaluation at baseline and 1-year follow up. Excisional treatment was offered as indicated. Histopathology was the reference standard.

MAIN OUTCOME MEASURES

Persistence, clearance and incidence of high-risk HPV infection; and persistence, progression, regression, cure and incidence of cervical dysplasia.

RESULTS

Among 300 women screened at baseline, 237 attended follow up (79%). High-risk HPV positivity significantly decreased from 28% at baseline to 20% at 1 year (P = 0.02). High-risk HPV persistence was 46% and clearance was 54%; incidence was high at 9%. Prevalence of cervical intraepithelial neoplasia Grade 2 (CIN2) or higher was most common in participants with incident high-risk HPV (53%). CIN2 or higher was also common in those with persistent high-risk HPV (32%) and even in those who cleared high-risk HPV (30%). Of the high-risk HPV-positive participants at baseline with <CIN2, 40% progressed to CIN2 or higher at follow up.

CONCLUSION

The high incidence of high-risk HPV and high-grade cervical dysplasia in women living with HIV after one round of high-risk HPV-based screening and treatment raises concern about the rate of progression of high-risk HPV infection to dysplasia. Persistent disease is common. Caution in spacing cervical cancer screening intervals using high-risk HPV testing in women living with HIV is warranted.

TWEETABLE ABSTRACT

High incidence and persistence of HPV and CIN2+ in women living with HIV 1 year after screening and treatment.

Dynamics of respect: Evidence from two different national and political contexts

In (post-)modern, plural societies, consisting of numerous subgroups, mutual respect between groups plays a central role for a constructive social and political life. In this article, we examine whether group members’ perception of being respected by outgroups fosters respect for these outgroups. In Study 1, we employed a panel sample of supporters of the Tea Party movement in the United States (N = 422). In Study 2, we employed a panel sample of members of the LGBTI community in Germany (N = 262). As disapproved target outgroups, we chose in Study 1 homosexuals in the United States, while in Study 2, we chose supporters of the German populist, right-wing political party „Alternative für Deutschland“. Our studies thus constituted a complementary, nearly symmetrical constellation of a liberal group and a conservative political group each. Among Tea Party movement supporters, respect from a disapproved outgroup consistently predicted respect for that outgroup. Among German LGBTI community members, this effect of respect from a disapproved outgroup was found in some of our analyses. For this latter sample, there was furthermore a tendency of societal respect to predict respect for a disapproved outgroup longitudinally. Additionally, we observed for both of our samples that respect from other ingroup members decreased respect for a disapproved outgroup. The dynamics of mutual respect in these two complementary intergroup contexts are discussed as well as the importance of direct intergroup reciprocity and superordinate group membership as routes to mutual respect.

Pseudo-RNA-Binding Domains Mediate RNA Structure Specificity in Upstream of N-Ras

RNA-binding proteins (RBPs) commonly feature multiple RNA-binding domains (RBDs), which provide these proteins with a modular architecture. Accumulating evidence supports that RBP architectural modularity and adaptability define the specificity of their interactions with RNA. However, how multiple RBDs recognize their cognate single-stranded RNA (ssRNA) sequences in concert remains poorly understood. Here, we use Upstream of N-Ras (Unr) as a model system to address this question. Although reported to contain five ssRNA-binding cold-shock domains (CSDs), we demonstrate that Unr includes an additional four CSDs that do not bind RNA (pseudo-RBDs) but are involved in mediating RNA tertiary structure specificity by reducing the conformational heterogeneity of Unr. Disrupting the interactions between canonical and non-canonical CSDs impacts RNA binding, Unr-mediated translation regulation, and the Unr-dependent RNA interactome. Taken together, our studies reveal a new paradigm in protein-RNA recognition, where interactions between RBDs and pseudo-RBDs select RNA tertiary structures, influence RNP assembly, and define target specificity.

Macrocyclic Peptides Uncover a Novel Binding Mode for Reversible Inhibitors of LSD1

Lysine-specific demethylase 1 (LSD1) is an epigenetic enzyme which regulates the methylation of Lys4 of histone 3 (H3) and is overexpressed in certain cancers. We used structures of H3 substrate analogues bound to LSD1 to design macrocyclic peptide inhibitors of LSD1. A linear, Lys4 to Met-substituted, 11-mer (4) was identified as the shortest peptide distinctly interacting with LSD1. It was evolved into macrocycle 31, which was >40 fold more potent (K _i = 2.3 μM) than 4. Linear and macrocyclic peptides exhibited unexpected differences in structure-activity relationships for interactions with LSD1, indicating that they bind LSD1 differently. This was confirmed by the crystal structure of 31 in complex with LSD1-CoREST1, which revealed a novel binding mode at the outer rim of the LSD1 active site and without a direct interaction with FAD. NMR spectroscopy of 31 suggests that macrocyclization restricts its solution ensemble to conformations that include the one in the crystalline complex. Our results provide a solid basis for the design of optimized reversible LSD1 inhibitors.

Structural Basis of an Asymmetric Condensin ATPase Cycle

The condensin protein complex plays a key role in the structural organization of genomes. How the ATPase activity of its SMC subunits drives large-scale changes in chromosome topology has remained unknown. Here we reconstruct, at near-atomic resolution, the sequence of events that take place during the condensin ATPase cycle. We show that ATP binding induces a conformational switch in the Smc4 head domain that releases its hitherto undescribed interaction with the Ycs4 HEAT-repeat subunit and promotes its engagement with the Smc2 head into an asymmetric heterodimer. SMC head dimerization subsequently enables nucleotide binding at the second active site and disengages the Brn1 kleisin subunit from the Smc2 coiled coil to open the condensin ring. These large-scale transitions in the condensin architecture lay out a mechanistic path for its ability to extrude DNA helices into large loop structures.

Muslims' experiences of equality recognition in Germany: Effects on identification with the larger society and on equality recognition of other societal subgroups

OBJECTIVES

Fostering the identification of societal minorities with the larger society is an essential political aim. In this article, we analyze whether minority members' perception of being recognized by society leads to a stronger identification with society, and whether this identification fosters more willingness to recognize other societal subgroups' members as equal members of society.

METHOD

Our analysis is based on both a cross-sectional (N = 1,059, 49% female, mean age = 31 years, 78% with migration background, i.e., first- to third-generation) and a longitudinal (N = 159, 57% female, mean age = 30 years, 76% with migration background) sample of Muslims living in Germany.

RESULTS

Structural equation modeling and path analyses suggested that the perception to be recognized by society as equals yielded stronger identification with Germany. In contrast, the perception that one's needs are recognized had no effect on the identification with Germany, while the perception of achievement recognition even tended to decrease identification with Germany. Identification with Germany, in turn, led to an increased willingness of respondents to extend equality recognition to subgroups' members whose beliefs and/or practices our respondents (on average) disapproved.

CONCLUSIONS

When the societal majority imparts to minorities a sense of being recognized as equals, this equality recognition colors the broader societal framework within which intergroup relations take shape. We further suggest that-if it is desired that subgroups identify with society-the most viable option is a multicultural model of society, which enables minorities to simultaneously retain their subgroup identity. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Structure, dynamics and roX2-lncRNA binding of tandem double-stranded RNA binding domains dsRBD1,2 of Drosophila helicase Maleless

Maleless (MLE) is an evolutionary conserved member of the DExH family of helicases in Drosophila. Besides its function in RNA editing and presumably siRNA processing, MLE is best known for its role in remodelling non-coding roX RNA in the context of X chromosome dosage compensation in male flies. MLE and its human orthologue, DHX9 contain two tandem double-stranded RNA binding domains (dsRBDs) located at the N-terminal region. The two dsRBDs are essential for localization of MLE at the X-territory and it is presumed that this involves binding roX secondary structures. However, for dsRBD1 roX RNA binding has so far not been described. Here, we determined the solution NMR structure of dsRBD1 and dsRBD2 of MLE in tandem and investigated its role in double-stranded RNA (dsRNA) binding. Our NMR and SAXS data show that both dsRBDs act as independent structural modules in solution and are canonical, non-sequence-specific dsRBDs featuring non-canonical KKxAXK RNA binding motifs. NMR titrations combined with filter binding experiments and isothermal titration calorimetry (ITC) document the contribution of dsRBD1 to dsRNA binding in vitro. Curiously, dsRBD1 mutants in which dsRNA binding in vitro is strongly compromised do not affect roX2 RNA binding and MLE localization in cells. These data suggest alternative functions for dsRBD1 in vivo.

Improving the sensitivity of FT-NMR spectroscopy by apodization weighted sampling

Apodization weighted acquisition is a simple approach to enhance the sensitivity of multidimensional NMR spectra by scaling the number of scans during acquisition of the indirect dimension(s). The signal content of the resulting spectra is identical to conventionally sampled data, yet the spectra show improved signal-to-noise ratios. There are no special requirements for data acquisition and processing: the time-domain data can be transformed with the same schemes used for conventionally recorded spectra, including Fourier transformation. The method is of general use in multidimensional liquid and solid state NMR experiments if the number of recorded transients per sampling point is bigger than the minimum required phase cycle of the pulse sequence.

Politicization as an antecedent of polarization: Evidence from two different political and national contexts

Using longitudinal research designs, we examine the role of politicization in the development of polarization. We conducted research in two different political and national contexts. In Study 1, we employ a panel sample of supporters of the Tea Party movement in the United States and examine the relationship between the strength of their politicization and their subsequent feelings towards conservatives versus liberals (affective polarization) as well as their subsequent perceptions of commonalities with conservatives versus liberals (cognitive polarization). In Study 2, we employ a panel sample of members of the lesbian, gay, bisexual, transgender, and intersex (LGBTI) community in Germany and examine the politicization-polarization link with regard to feelings towards, and perceived commonalities with, feminists versus supporters of a populist right-wing political party. We obtained converging evidence suggesting that politicization promotes both affective and cognitive polarization. There was also some, but very limited evidence pointing to reverse causation. The danger of escalating polarization is discussed.

Disapproved, but Tolerated: The Role of Respect in Outgroup Tolerance

We conducted two studies to test the hypothesis that respect for disapproved outgroups increases tolerance toward them. In Study 1, we employed a panel sample of supporters of the Tea Party movement in the United States and found that Tea Party supporters' respect for homosexuals and Muslims as equal fellow citizens positively predicted Tea Party supporters' tolerance toward these groups. There was no indication that alternative recognition processes (i.e., achievement recognition or need recognition) played a similar role in the development of tolerance. Study 2 replicated the respect-tolerance link with the experimental method and a more comprehensive measure of tolerance. In particular, it demonstrated that the link also holds with regard to tolerance in the public or political sphere. The wider implications of our research for societal pluralism are discussed.

Evaluating the efficiency of the Dental Teacher system as a digital preclinical teaching tool

AIM

To investigate the use of a preparation evaluation system for enhancing the learning and performance of undergraduate dental students when cutting preparations.

MATERIALS AND METHODS

Two groups of eighteen students each were randomly chosen from the fourth year of the dental programme. The task chosen for this study was to make a cavity in preparation for a mesio-occlusal ceramic onlay in a plastic tooth. The dimensions of the cavity were defined, and 2 burs of known size were used for preparation. For assessment, each tooth preparation was scanned with a digital scanner and analysed using the Dental Teacher software. In the control group, a second corrective preparation was made following the supervisor's instructions. In the test group, the second preparation was made based on Dental Teacher analysis. The final cavities were all scanned and assessed by Dental Teacher comparing the similarity of students' onlay cavity preparations to the ideal preparation. All data were recorded and analysed by the software, including cavity depth and width in the occlusal and proximal box, the extent of mesiobuccal cusp reduction and shoulder width around the mesiobuccal cusp. Finally, the data were statistically evaluated using a Wilcoxon matched pairs test and a Mann-Whitney U test.

RESULTS

Three of the 6 cavity dimension parameters improved significantly in the test group whilst no improvement was found in the control group. A positive correlation was found between the improvement and the deviation measured for the first preparations, and it was stronger in the test group than in the control group.

CONCLUSIONS

The use of Dental Teacher helped students to learn the preparation technique for onlay restorations more efficiently and seems to be a promising and useful method to facilitate their individual performance. Student feedback showed a great demand for digital aids in education.

A realistic view on disagreement: Roots, resolutions, and the trauma of the scientist

Building on insights from social psychology and political philosophy, I develop a realistic view on disagreement. According to this view, disagreements among people can be traced back to the heterogeneity of social reality and people’s differing social positioning in it with the relativity of identities playing a mediating role. I discuss theoretical and meta-theoretical as well as practical and normative implications of such a view. I also look into the fate of the scientist when she leaves the narrow confines of academia and enters the public sphere in order to intervene in disagreements. Drawing on the vertical structuration of social reality and the corresponding hierarchical or nested nature of people’s identities, I elaborate on a promising path to the resolution of disagreement, in which both scientists and social critics can play constructive roles. This elaboration eventually puts a proceduralist slant on my realistic view on disagreements and their resolution.

DENR-MCTS1 heterodimerization and tRNA recruitment are required for translation reinitiation

The succession of molecular events leading to eukaryotic translation reinitiation—whereby ribosomes terminate translation of a short open reading frame (ORF), resume scanning, and then translate a second ORF on the same mRNA—is not well understood. Density-regulated reinitiation and release factor (DENR) and multiple copies in T-cell lymphoma-1 (MCTS1) are implicated in promoting translation reinitiation both in vitro in translation extracts and in vivo. We present here the crystal structure of MCTS1 bound to a fragment of DENR. Based on this structure, we identify and experimentally validate that DENR residues Glu42, Tyr43, and Tyr46 are important for MCTS1 binding and that MCTS1 residue Phe104 is important for tRNA binding. Mutation of these residues reveals that DENR-MCTS1 dimerization and tRNA binding are both necessary for DENR and MCTS1 to promote translation reinitiation in human cells. These findings thereby link individual residues of DENR and MCTS1 to specific molecular functions of the complex. Since DENR–MCTS1 can bind tRNA in the absence of the ribosome, this suggests the DENR–MCTS1 complex could recruit tRNA to the ribosome during reinitiation analogously to the eukaryotic initiation factor 2 (eIF2) complex in cap-dependent translation.

Usually, eukaryotic ribosomes translate only a single open reading frame (ORF) on an mRNA and then dissociate from the mRNA. In some cases, when there is a short upstream open reading frame (uORF) that precedes the main ORF, ribosomes can translate the uORF, terminate translation, and then undergo a poorly understood process called “translation reinitiation” whereby they resume scanning for another AUG initiation codon and then translate the main ORF. The molecular functions required for translation reinitiation are not known. We previously showed that two noncanonical initiation factors, density-regulated reinitiation and release factor (DENR) and multiple copies in T-cell lymphoma-1 (MCTS1), are involved in this process. We show here, based on a structure of MCTS1 bound to a fragment of DENR, that in order to successfully promote translation reinitiation, DENR and MCTS1 need to dimerize, and they need to bind tRNA. We thereby identify two molecular functions needed for translation reinitiation.

Politicization in the name of the majority: The role of cultural, economic, and political grievances

The article reports two experiments that examined politicization in the name of the majority population and intergroup polarization as a function of perceived grievances of the majority population. To manipulate perceived majority grievances, we used three different injustice frames (cultural, economic, political), each of which targeted an important arena of societal participation and thus a typical breeding ground for societal injustices and psychological grievances. In addition, both experiments included a (no frame) control condition. The samples recruited for the two experiments differed from each other in (left–right) political orientation and consequently in their perceptions of and reactions to potential majority grievances. The most striking differential influences were observed for the cultural grievance symbolized by the political correctness norm. However, both experiments provided evidence that majority politicization mediates the effect of majority grievances on intergroup polarization and that, in contrast to the divisive role of majority politicization, majority solidarity likely fosters social inclusion.

In Vivo Demonstration of the Haldane Effect during Extracorporeal Gas Exchange

During the extracorporeal support (LFPPV-ECCO2R) of 11 patients suffering from severe lung failure (ARDS), we consistently noticed a higher arterial than mixed-venous PCO2 in blood samples drawn at the same time. Two explanations are possible: a) the Haldane effect (HE), b) CO2 from lung tissue metabolism. In order to distinguish changes in PCO2 due to the HE from those due to tissue CO2 production, CO2 content (CCO2) was calculated. The results were compared to animal experiments with hyperoxic apnea, after which arterial and mixed-venous samples were drawn simultaneously. All blood gas samples were analyzed for pH, PCO2, PO2, and 02-saturation, from which CCO2 was calculated. In both groups, PaCO2 was 2.15 mmHg (2.7 mmHg respectively) higher at a lower CaCO2 (-2.87 ml/l, -14.9 ml/l). Oxygen saturation increased by 8.1% in the human group and 17.8% in the animal group. A significant relationship was found between changes in PCO2 and changes in 02-saturation. This is a demonstration of the Haldane effect.

Grundriss einer sozialpsychologischen Respekttheorie

Zusammenfassung. In diesem Beitrag entwickele ich den Grundriss einer sozialpsychologischen Respekttheorie. Mein Augenmerk richtet sich insbesondere auf die Bedeutung von Respekt für das Zusammenleben in der pluralistischen Gesellschaft. Im Rahmen eines Brückenschlags zu anerkennungstheoretischen Überlegungen sozialphilosophischer Provenienz erarbeite ich zunächst eine Konzeption von Respekt als Gleichheitsanerkennung. Anschließend diskutiere ich empirische Befunde aus eigenen Forschungsarbeiten, die zum einen die grundlegende Respektkonzeption validieren und zum anderen wichtige soziale Auswirkungen von Respekt (sowie von mangelndem Respekt) beleuchten. Der Beitrag schließt mit Überlegungen zur Dynamik von Respekt und einem Ausblick auf politisierte Anerkennungskämpfe in pluralistischen Gesellschaften.

A Social Recognition Approach to Autonomy: The Role of Equality-Based Respect

Inspired by philosophical reasoning about the connection between equality and freedom, we examined whether experiences of (equality-based) respect increase perceived autonomy. This link was tested with generalized experiences of respect and autonomy people make in their daily lives (Study 1) and with more specific experiences of employees at the workplace (Study 2). In both studies, respect strongly and independently contributed to perceived autonomy over and above other forms of social recognition (need-based care and achievement-based social esteem) and further affected (life/work) satisfaction. Study 3 experimentally confirmed the hypothesized causal influence of respect on perceived autonomy and demonstrated that this effect further translates into social cooperation. The respect-cooperation link was simultaneously mediated by perceived autonomy and superordinate collective identification. We discuss how the recognition approach, which differentiates between respect, care, and social esteem, can enrich research on autonomy.

Muslims' tolerance towards outgroups: Longitudinal evidence for the role of respect

We employed a longitudinal design to test two hypotheses concerning Muslims' respect for and tolerance towards disapproved outgroups. In support of the outgroup respect-tolerance hypothesis derived from the disapproval-respect model of social tolerance, our results strongly suggest that respect for disapproved outgroups is not just a correlate of tolerance towards those groups, but a causal antecedent. In support of the intergroup respect-reciprocity hypothesis, we identified respect from disapproved outgroups as an effective source of respect for disapproved outgroups and therefore also as a (distal) source of tolerance towards those groups. Normative and political implications are discussed.