RpfC (Rv1884) atomic structure shows high structural conservation within the resuscitation promoting factor catalytic domain

We report the first structure of the catalytic domain of RpfC (Rv1884), one of theresuscitation-promoting factors (RPFs) from Mycobacterium tuberculosis. The structure was solved using molecular replacement, once the space group had been correctly identified as twinned P21 rather than the apparent C2221 by searching for anomalous scattering sites in P1. The structure displays a very high degree of structural conservation with the structures of the catalytic domains of RpfB (Rv1009) and RpfE (Rv2450) already published. This structural conservation highlights the importance of the versatile domain composition of the RPF family

Molecular dynamics of ion transport through the open conformation of a bacterial voltage-gated sodium channel

The crystal structure of the open conformation of a bacterial voltage-gated sodium channel pore from Magnetococcus sp. (NaVMs) has provided the basis for a molecular dynamics study defining the channel’s full ion translocation pathway and conductance process, selectivity, electrophysiological characteristics, and ion-binding sites. Microsecond molecular dynamics simulations permitted a complete time-course characterization of the protein in a membrane system, capturing the plethora of conductance events and revealing a complex mixture of single and multi-ion phenomena with decoupled rapid bidirectional water transport. The simulations suggest specific localization sites for the sodium ions, which correspond with experimentally determined electron density found in the selectivity filter of the crystal structure. These studies have also allowed us to identify the ion conductance mechanism and its relation to water movement for the NavMs channel pore and to make realistic predictions of its conductance properties. The calculated single-channel conductance and selectivity ratio correspond closely with the electrophysiology measurements of the NavMs channel expressed in HEK 293 cells. The ion translocation process seen in this voltage-gated sodium channel is clearly different from that exhibited by members of the closely related family of voltage-gated potassium channels and also differs considerably from existing proposals for the conductance process in sodium channels. These studies simulate sodium channel conductance based on an experimentally determined structure of a sodium channel pore that has a completely open transmembrane pathway and activation gate

A structurally conserved motif in γ-herpesvirus uracil-DNA glycosylases elicits duplex nucleotide-flipping

Efficient γ-herpesvirus lytic phase replication requires a virally encoded UNG-type uracil-DNA glycosylase as a structural element of the viral replisome. Uniquely, γ-herpesvirus UNGs carry a seven or eight residue insertion of variable sequence in the otherwise highly conserved minor-groove DNA binding loop. In Epstein–Barr Virus [HHV-4] UNG, this motif forms a disc-shaped loop structure of unclear significance. To ascertain the biological role of the loop insertion, we determined the crystal structure of Kaposi’s sarcoma-associated herpesvirus [HHV-8] UNG (kUNG) in its product complex with a uracil-containing dsDNA, as well as two structures of kUNG in its apo state. We find the disc-like conformation is conserved, but only when the kUNG DNA-binding cleft is occupied. Surprisingly, kUNG uses this structure to flip the orphaned partner base of the substrate deoxyuridine out of the DNA duplex while retaining canonical UNG deoxyuridine-flipping and catalysis. The orphan base is stably posed in the DNA major groove which, due to DNA backbone manipulation by kUNG, is more open than in other UNG–dsDNA structures. Mutagenesis suggests a model in which the kUNG loop is pinned outside the DNA-binding cleft until DNA docking promotes rigid structuring of the loop and duplex nucleotide flipping, a novel observation for UNGs

Critical Conversations around Hiring Equity and Anti-Racist Search Processes

When the COVID-19 pandemic shut down institutions in March 2020, many academic programs faced budget cuts and hiring freezes (Friga, 2020). The impact of budget cuts most severely impacted HBCU’s and rural colleges (Kelchen et al., 2021). Yet, as the pandemic restrictions eased and some schools found ways to begin hiring again; however, things were different this time. Many schools conducted their searches entirely virtually (Banks et al., 2020). As many social work educators can attest, a switch from in-person to virtual methods presented unique challenges (Paceley et al., 2021). This 4-person panel included a successful job candidate and three members of search committees. The panel shared tips and tricks that helped the searches run smoothly in the virtual environment. Additionally, there was a focus on making the virtual environment as welcoming and attractive as possible. The panel presented perspectives from rural and urban teaching-focused and research-focused institutions ranging in Carnegie Classifications from “R1: Doctoral Universities – Very high research activity” to “Master\u27s College and University”. These perspectives encompassed both PWI and HBCU. Critical conversations around hiring equity and antiracist search processes are an important part of higher education leadership. As social workers, we must act to eliminate racist hiring trends in higher education and bring equity to the front of the table in hiring conversations (Gates et al., 2021). Participants in this panel confronted their own biases related to antiracist search practices and learned new strategies for faculty searches in the landscape of an ongoing pandemic (Fariña et al., 2021)

Effects of Episodic Food Insecurity on Psychological and Physiological Responses in African American Women With Obesity (RESPONSES): Protocol for a Longitudinal Observational Cohort Study

Background: Food insecurity is a risk factor for multiple chronic diseases, including obesity. Importantly, both food insecurity and obesity are more prevalent in African American women than in other groups. Furthermore, food insecurity is considered a cyclic phenomenon, with episodes of food adequacy (ie, enough food to eat) and food shortage (ie, not enough food to eat). More research is needed to better understand why food insecurity is linked to obesity, including acknowledging the episodic nature of food insecurity as a stressor and identifying underlying mechanisms. Objective: The objective of this study is to investigate the episodic nature of food insecurity as a stressor via responses in body weight and psychological and physiological parameters longitudinally and do so in a health-disparate population-African American women. Methods: We enrolled 60 African American women (food-insecure cohort: n=30, 50%; food-secure cohort: n=30, 50%) aged 18-65 years with obesity (BMI 30-50 kg/m2) to measure (1) daily body weight remotely over 22 weeks and (2) psychological and physiological parameters via clinic assessments at the beginning and end of the 22-week study. Furthermore, we are assessing episodes of food insecurity, stress, hedonic eating, and appetite on a weekly basis. We hypothesize that food-insecure African American women with obesity will demonstrate increased body weight and changes in psychological and physiological end points, whereas food-secure African American women with obesity will not. We are also examining associations between changes in psychological and physiological parameters and changes in body weight and performing a mediation analysis on the psychological parameters assessed at the study midpoint. Psychological questionnaires are used to assess stress; executive function, decision-making, and motivation; and affect and nonhomeostatic eating. Physiological measurements are used to evaluate the levels of cortisol, dehydroepiandrosterone-sulfate (DHEA-S), C-reactive protein, thyroid hormones, blood glucose, glycated hemoglobin, and insulin, as well as allostatic load. Results: This study has completed participant recruitment (n=60). At the time of study enrollment, the mean age of the participants was almost 47 (SD 10.8) years, and they had a mean BMI of 39.6 (SD 5.31) kg/m2. All data are anticipated to be collected by the end of 2023. Conclusions: We believe that this is the first study to examine changes in body weight and psychological and physiological factors in food-insecure African American women with obesity. This study has significant public health implications because it addresses the cyclic nature of food insecurity to identify underlying mechanisms that can be targeted to mitigate the adverse relationship between food insecurity and obesity and reduce health disparities in minority populations

IKKγ mimetic peptides block the resistance to apoptosis associated with KSHV infection

Primary effusion lymphoma (PEL) is a lymphogenic disorder associated with KSHV infection. Key to the survival and proliferation of PEL is the canonical NF-kB pathway that becomes constitutively activated following overexpression of the viral oncoprotein ks-vFLIP. This arises from its capacity to form a complex with the modulatory subunit of the IKK kinase, IKKgamma (or NEMO) resulting in the overproduction of proteins that promote cellular survival and prevent apoptosis; both of which are important drivers of tumourigenesis. Using a combination of cell based and biophysical assays together with structural techniques, we show that the observed resistance to cell death is largely independent of autophagy or major death receptor signalling pathways and demonstrate that direct targeting of the ks-vFLIP-IKKgamma interaction both in cells and in vitro can be achieved using IKKgamma mimetic peptides. Our results further reveal that these peptides not only induce cell killing, but potently sensitise PEL to the pro-apoptotic agents tumour necrosis factor alpha and etoposide and are the first to confirm ks-vFLIP as a tractable target for the treatment of PEL and related disorders

NEMO oligomerization and its ubiquitin-binding properties

The IKK [IκB (inhibitory κB) kinase] complex is a key regulatory component of NF-κB (nuclear factor κB) activation and is responsible for mediating the degradation of IκB, thereby allowing nuclear translocation of NF-κB and transcription of target genes. NEMO (NF-κB essential modulator), the regulatory subunit of the IKK complex, plays a pivotal role in this process by integrating upstream signals, in particular the recognition of polyubiquitin chains, and relaying these to the activation of IKKα and IKKβ, the catalytic subunits of the IKK complex. The oligomeric state of NEMO is controversial and the mechanism by which it regulates activation of the IKK complex is poorly understood. Using a combination of hydrodynamic techniques we now show that apo-NEMO is a highly elongated, dimeric protein that is in weak equilibrium with a tetrameric assembly. Interaction with peptides derived from IKKβ disrupts formation of the tetrameric NEMO complex, indicating that interaction with IKKα and IKKβ and tetramerization are mutually exclusive. Furthermore, we show that NEMO binds to linear di-ubiquitin with a stoichiometry of one molecule of di-ubiquitin per NEMO dimer. This stoichiometry is preserved in a construct comprising the second coiled-coil region and the leucine zipper and in one that essentially spans the full-length protein. However, our data show that at high di-ubiquitin concentrations a second weaker binding site becomes apparent, implying that two different NEMO–di-ubiquitin complexes are formed during the IKK activation process. We propose that the role of these two complexes is to provide a threshold for activation, thereby ensuring sufficient specificity during NF-κB signalling

Representative Classification of Teacher’s Perceptions of Externalizing Behaviors

*This report was prepared as part of course requirements for SOW 6938 and has not been submitted for publication in a peer-reviewed journal. Background: This study aimed to identify what contributors influenced whether a teacher observed externalizing behaviors among fourth-grade children. Methods: Data was obtained from the Early Childhood Longitudinal Studies (ECLS) Program data set provided by the National Center for Education Statistics. A Classification and Regression Tree (CART) analysis was conducted to determine the relative importance of the varying factors that were attributed to externalizing behaviors. Results: The CART analysis revealed that teacher classification of children as exhibiting externalizing problem behaviors was influenced by internalizing problem behaviors, race, and gender. Exhibiting internalizing behaviors was the most significant contributor. Lower internalizing behaviors were classified as lower externalizing behaviors. Higher internalizing behaviors were further classified by gender, with female students being less likely attributed to high externalizing behaviors. Male students were further classified by race; Caucasian and Hispanic male students were classified with lower externalizing behaviors than African American students. Caucasian and Hispanic students were then classified by internalizing behaviors, with higher internalizing behaviors being classified toward higher externalizing behaviors. Conclusion: The findings are supported by the extant literature stating that African American males are more often classified as exhibiting externalizing behaviors. Future implications for research and practice will be discussed