A Micrarchaeon isolate is covered by a proteinaceous S-Layer

In previous publications, it was hypothesized that Micrarchaeota cells are covered by two individual membrane systems. This study proves that at least the recently cultivated “ Candidatus Micrarchaeum harzensis A_DKE” possesses an S-layer covering its cytoplasmic membrane. The potential S-layer protein was found to be among the proteins with the highest abundance in “ Ca. Micrarchaeum harzensis A_DKE” and in silico characterisation of its primary structure indicated homologies to other known S-layer proteins. Homologues of this protein were found in other Micrarchaeota genomes, which raises the question of whether the ability to form an S-layer is a common trait within this phylum. The S-layer protein seems to be glycosylated and the Micrarchaeon expresses genes for N-glycosylation under cultivation conditions, despite not being able to synthesize carbohydrates. Electron micrographs of freeze-etched samples of a previously described co-culture, containing Micrarchaeum A_DKE and a Thermoplasmatales member as its host organism, verified the hypothesis of an S-layer on the surface of “ Ca. Micrarchaeum harzensis A_DKE”. Both organisms are clearly distinguishable by cell size, shape and surface structure. Importance Our knowledge about the DPANN superphylum, which comprises several archaeal phyla with limited metabolic capacities, is mostly based on genomic data derived from cultivation-independent approaches. This study examined the surface structure of a recently cultivated member “ Candidatus Micrarchaeum harzensis A_DKE”, an archaeal symbiont dependent on an interaction with a host organism for growth. The interaction requires direct cell contact between interaction partners, a mechanism which is also described for other DPANN archaea. Investigating the surface structure of “ Ca. Micrarchaeum harzensis A_DKE” is an important step towards understanding the interaction between Micrarchaeota and their host organisms and living with limited metabolic capabilities, a trait shared by several DPANN archaea.

Moralizing Immigration: Political Framing, Moral Conviction, and Polarization in the United States and Denmark

Morally charged rhetoric is commonplace in political discourse on immigration but scholars have not examined how it affects divisions over the issue among the public. To address this gap, we employ preregistered survey experiments in two countries where anti-immigration rhetoric has been prominent: the United States and Denmark. We demonstrate that exposure to moralized messages leads respondents to place greater moral weight on their existing immigration opinions and become more averse to political leaders and, in the United States, social interaction partners who espouse opposite beliefs. This suggests that political moralization contributes to moral conflict and affective polarization. We find no evidence, however, that moral framing produces attitudinal polarization—that is, more extreme immigration opinions. Our study helps make sense of the heightened intensity of anti-immigrant politics even when attitudes are stable. It also suggests a promising avenue for comparative research on affective polarization by shifting the focus from partisanship to the moralization of existing issue disagreements.

Vps68 cooperates with ESCRT-III in intraluminal vesicle formation

The endosomal sorting complex required for transport (ESCRT)-III mediates budding and abscission of intraluminal vesicles (ILVs) into multivesicular endosomes. To further define the role of the ESCRT-III associated protein Mos10/Vps60 in ILV formation, we screened for new interaction partners by SILAC/MS. Here, we focused on the newly identified interaction partner Vps68. Our data suggest that Vps68 cooperates with ESCRT-III in ILV formation. The deletion of VPS68 caused a sorting defect similar to the SNF7 deletion, when the cargo load was high. The composition of ESCRT-III was altered, the level of core components was higher and the level of associated proteins was lower in the deletion strain. This suggests that a shift occurs from an active complex to a disassembly competent complex and that this shift is blocked in the Δvps68 strain. We present evidence that during this shift Snf7 is replaced by Mos10. Vps68 has an unusual membrane topology. Two of its potential membrane helices are amphipathic helices localized to the luminal side of the endosomal membrane. Based on this membrane topology we propose that Vps68 and ESCRT-III cooperate in the abscission step by weakening the luminal and cytosolic leaflets of the bilayer at the abscission site.

Telomerase Interaction Partners–Insight from Plants

Telomerase, an essential enzyme that maintains chromosome ends, is important for genome integrity and organism development. Various hypotheses have been proposed in human, ciliate and yeast systems to explain the coordination of telomerase holoenzyme assembly and the timing of telomerase performance at telomeres during DNA replication or repair. However, a general model is still unclear, especially pathways connecting telomerase with proposed non-telomeric functions. To strengthen our understanding of telomerase function during its intracellular life, we report on interactions of several groups of proteins with the Arabidopsis telomerase protein subunit (AtTERT) and/or a component of telomerase holoenzyme, POT1a protein. Among these are the nucleosome assembly proteins (NAP) and the minichromosome maintenance (MCM) system, which reveal new insights into the telomerase interaction network with links to telomere chromatin assembly and replication. A targeted investigation of 176 candidate proteins demonstrated numerous interactions with nucleolar, transport and ribosomal proteins, as well as molecular chaperones, shedding light on interactions during telomerase biogenesis. We further identified protein domains responsible for binding and analyzed the subcellular localization of these interactions. Moreover, additional interaction networks of NAP proteins and the DOMINO1 protein were identified. Our data support an image of functional telomerase contacts with multiprotein complexes including chromatin remodeling and cell differentiation pathways.

mGBP2 engages Galectin-9 and Cytoskeleton-associated Protein 4 for immunity against Toxoplasma gondii

Guanylate binding proteins (GBPs) are large interferon-inducible GTPases, executing essential host defense activities against Toxoplasma gondii, an invasive intracellular apicomplexan protozoan parasite of global importance. T. gondii establishes a parasitophorous vacuole (PV) which shields the parasite from the host's intracellular defense mechanisms. Murine GBPs (mGBPs) recognize T. gondii PVs and assemble into supramolecular mGBP homo- and heterocomplexes that are required for the disruption of the membrane of PVs eventually resulting in the cell-autonomous immune control of vacuole-resident pathogens. We have previously shown that mGBP2 plays an important role in T. gondii immune control. Here, in order to unravel mGBP2 functions, we report Galectin-9 (Gal9) and cytoskeleton-associated protein 4 (Ckap4) as critical mGBP2 interaction partners engaged for immunity to T. gondii. Interestingly, Gal9 and Ckap4 also accumulate and colocalize with mGBP2 at the T. gondii PV. Furthermore, we could prove the requirement of Gal9 and Ckap4 for growth control of T. gondii by CRISPR/Cas9 mediated gene editing. These discoveries clearly indicate that mGBP2 engages Gal9 and Ckap4 and that Gal9 and Ckap4 are critical factors for the mGBP2 coordinated cell autonomous host defense mechanism against T. gondii.

Parent-child nonverbal engagement during read versus sung book-sharing in preschoolers with and without ASD

Providing natural opportunities that scaffold interpersonal engagement is important for supporting social interactions for young children with autism spectrum disorder (ASD). Musical activities are often motivating, familiar, and predictable, and may support both children and their interaction partners by providing opportunities for shared social engagement. We assessed multiple facets of nonverbal social engagement—child and caregiver visual attention and interpersonal movement coordination—during musical (song) and non-musical (picture) book-sharing contexts in caregiver–child dyads of preschoolers with ( n = 13) and without ( n = 16) ASD. Overall, children with ASD demonstrated reduced visual attention during the book sharing activity, as well as reduced movement coordination with their caregivers, compared to children with typical development. Children in both diagnostic groups, as well as caregivers, demonstrated greater visual attention (gaze toward the activity and/or social partner) during song books compared to picture books. Visual attention behavior was correlated between children and caregivers in the ASD group but only in the song book condition. Findings highlight the importance of considering how musical contexts impact the behavior of both partners in the interaction. Musical activities may support social engagement by modulating the behavior of both children and caregivers.

Proteomic analysis identifies ZMYM2 as endogenous binding partner of TBX18 protein in 293 and A549 cells

The TBX18 transcription factor regulates patterning and differentiation programs in the primordia of many organs yet the molecular complexes in which TBX18 resides to exert its crucial transcriptional function in these embryonic contexts have remained elusive. Here, we used 293 and A549 cells as an accessible cell source to search for endogenous protein interaction partners of TBX18 by an unbiased proteomic approach. We tagged endogenous TBX18 by CRISPR/Cas9 targeted genome editing with a triple FLAG peptide, and identified by anti-FLAG affinity purification and subsequent LC-MS analysis the ZMYM2 protein to be statistically enriched together with TBX18 in both 293 and A549 nuclear extracts. Using a variety of assays, we confirmed binding of TBX18 to ZMYM2, a component of the CoREST transcriptional corepressor complex. Tbx18 is coexpressed with Zmym2 in the mesenchymal compartment of the developing ureter of the mouse, and mutations in TBX18and in ZMYM2 were recently linked to congenital anomalies in the kidney and urinary tract (CAKUT) in line with a possible in vivo relevance of TBX18-ZMYM2 protein interaction in ureter development.

Human TRMT112-Methyltransferase Network Consists of Seven Partners Interacting with a Common Co-Factor

Methylation is an essential epigenetic modification mainly catalysed by S-Adenosyl methionine-dependent methyltransferases (MTases). Several MTases require a cofactor for their metabolic stability and enzymatic activity. TRMT112 is a small evolutionary conserved protein that acts as a co-factor and activator for different MTases involved in rRNA, tRNA and protein methylation. Using a SILAC screen, we pulled down seven methyltransferases—N6AMT1, WBSCR22, METTL5, ALKBH8, THUMPD2, THUMPD3 and TRMT11—as interaction partners of TRMT112. We showed that TRMT112 stabilises all seven MTases in cells. TRMT112 and MTases exhibit a strong mutual feedback loop when expressed together in cells. TRMT112 interacts with its partners in a similar way; however, single amino acid mutations on the surface of TRMT112 reveal several differences as well. In summary, mammalian TRMT112 can be considered as a central “hub” protein that regulates the activity of at least seven methyltransferases.

Network analysis of Dengue NS1 interacting core human proteins driving dengue pathogenesis

Aim: We aimed to identify critical human proteins involved in cathepsin L regulation Background: It has been shown that Dengue Virus (DENV) NS1 activates cathepsin L (CTSL). The CTSL activates heparanase, which cleaves heparan sulfate proteoglycans and causes dengue pathogenesis. NS1 directly interacts with PTBP1 and Gab proteins. Gab protein activates the Ras signaling pathway. Still, no known direct interaction partners are linking GAB1 to cathepsin L. Objective: Our objective includes three main points.1-Network analysis of NS1 interacting human proteins 2- Identification of protein-drug and protein-disease interactions 3- Identification of core proteins involved in cathepsin L regulation. Method: We collected NS1 interacting Human proteins from DenHunt, Int-Act Molecular Interaction Database, Virus Mentha, Virus Pathogen Database and Analysis Resource (ViPR), and Virus MINT. We employed Pesca, cytohubba, and centiscape as the significant plug-ins in Cytoscape for network analysis. To study protein-diseases and protein-drugs interaction, we used NetworkAnalyst. Result: Based on the prior knowledge on the interaction of NS1 with GAB1 and PTBP1 human proteins, we found several core proteins that drive dengue pathogenesis. The proteins EED, NXF1, and MOV10, are the mediators between PTBP1 and CTSL. Similarly, DNM2, GRB2, PXN, PTPRC, and NTRK1 mediate GAB1 and PTBP1. The common first neighbors of MOV10, NXF1, and EED were identified, and the common primary pathways in all three subnetworks were mRNA processing and protein translation. The common interaction partners were considered for drug and disease network analysis. These proteins were; PARP1, NFKB2, HDAC2, SLC25A4, ATP5A1, EPN1, CTSL, UBR4, CLK3, and ARPC4. PARP1 was the highly connected node in the protein-drug network. The highest degree protein, LMNA, was associated with many diseases. The NXF1 is connected with LMNA. Here, we reported one essential protein, namely, NXF1 protein, which links PTBP1 with CTSL. The NXF1 is also connected with TPM3, which is connected to CTSL. Conclusion: We listed functionally important proteins which are involved in cathepsin L activation. Based on network properties, we proposed, NXF1 and TPM3 are the important high centrality proteins in dengue infection.

Syntaxin 5 determines Weibel-Palade body size and Von Willebrand factor secretion by controlling Golgi architecture

Von Willebrand factor (VWF) is a multimeric hemostatic protein primarily synthesized in endothelial cells (ECs). VWF is stored in endothelial storage organelles, the Weibel-Palade bodies (WPBs), whose biogenesis strongly depends on VWF anterograde trafficking and Golgi architecture. Elongated WPB morphology is correlated to longer VWF strings with better adhesive properties. We previously identified the SNARE SEC22B, which is involved in anterograde ER-to-Golgi transport, as a novel regulator of WPB elongation. To elucidate novel determinants of WPB morphology we explored endothelial SEC22B interaction partners in a mass spectrometrybased approach, identifying the Golgi SNARE Syntaxin 5 (STX5). We established STX5 knockdown in ECs using shRNA-dependent silencing and analyzed WPB and Golgi morphology, using confocal and electron microscopy. STX5-depleted ECs exhibited extensive Golgi fragmentation and decreased WPB length, which was associated with reduced intracellular VWF levels, and impaired stimulated VWF secretion. However, the secretion-incompetent organelles in shSTX5 cells maintained WPB markers such as Angiopoietin 2, P-selectin, Rab27A, and CD63. Taken together, our study has identified SNARE protein STX5 as a novel regulator of WPB biogenesis.