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The principle of size effect has been noticed a century ago, which has nowadays been widely used to express the activity enhancement of a catalyst as a result of size...

Biotin is an essential micro-nutrient across the three domains of life. The paradigm earlier step of biotin synthesis denotes “BioC-BioH” pathway in Escherichia coli. Here we report that BioZ bypasses the canonical route to begin biotin synthesis. In addition to its origin of Rhizobiales, protein phylogeny infers that BioZ is domesticated to gain an atypical role of β-ketoacyl-ACP synthase III. Genetic and biochemical characterization demonstrates that BioZ catalyzes the condensation of glutaryl-CoA (or ACP) with malonyl-ACP to give 5’-keto-pimeloyl ACP. This intermediate proceeds via type II fatty acid synthesis (FAS II) pathway, to initiate the formation of pimeloyl-ACP, a precursor of biotin synthesis. To further explore molecular basis of BioZ activity, we determine the crystal structure of Agrobacterium tumefaciens BioZ at 1.99 Å, of which the catalytic triad and the substrate-loading tunnel are functionally defined. In particular, we localize that three residues (S84, R147, and S287) at the distant bottom of the tunnel might neutralize the charge of free C-carboxyl group of the primer glutaryl-CoA. Taken together, this study provides molecular insights into the BioZ biotin synthesis pathway., Biotin is an essential enzyme cofactor and two pathways for the generation of the biotin precursor pimeloyl-ACP are known. Here, the authors identify and characterize a third pathway for biotin precursor synthesis involving BioZ and they also present the Agrobacterium tumefaciens BioZ crystal structure.

In mammals, type I IFNs, which commonly contain one or two disulfide bonds, activate the JAK-STAT signaling pathway through binding to the common cell surface receptor formed by IFN-α/β receptor (IFNAR)1 and IFNAR2 subunits. Although type I IFNs are also known to be essential for antiviral defense in teleost fish, very little is known about mechanisms underlying the recognition of fish type I IFNs by associated receptors. In this study, we demonstrate that a type I IFN of large yellow croaker Larimichthys crocea (LcIFNi), belonging to a new subgroup of fish type I IFNs, triggers antiviral response via the conserved JAK-STAT pathway through stable binding with a heterodimeric receptor comprising subunits LcCRFB5 and LcCRFB2. LcIFNi binds to LcCRFB5 with a much higher affinity than to LcCRFB2. Furthermore, we determined the crystal structure of LcIFNi at a 1.39 Å resolution. The high-resolution structure is, to our knowledge, the first reported structure of a type I IFN with three disulfide bonds, all of which were found to be indispensable for folding and stability of LcIFNi. Using structural analysis, mutagenesis, and biochemical assays, we identified key LcIFNi residues involved in receptor interaction and proposed a structural model of LcIFNi bound to the LcCRFB2–LcCRFB5 receptor. The results show that LcIFNi–LcCRFB2 exhibits a similar binding pattern to human IFN-ω–IFNAR2, whereas the binding pattern of LcIFNi–LcCRFB5 is quite different from that of IFN-ω–IFNAR1. Altogether, our findings reveal the structural basis for receptor interaction and signaling of a type I IFN with three disulfide bonds and provide new insights into the mechanisms underlying type I IFN recognition in teleosts.

The design of satisfied catalytic activity and stable catalysts for the oxygen evolution reaction (OER) is crucial in the production of hydrogen in electrolyzed water. Herein, S-doping NiCo-metal organic framework (NiCoS-MOF) were prepared successfully in situ on a nickel foamed (NF) substrate by used terephthalic acid (TPA) as an organic ligand via the original one-step solvothermal process, NiCoS-MOF reveals the electrocatalytic performance by the low overpotential of 71 mV at 10 mA cm−2 and the tafel slope of 74.4 mV dec−1 under alkaline condition (1 M KOH) served as OER electrodes directly. The i-t curve for 48 h at 1.50 and 2.14 V (vs.REH) showed excellent stability of NiCoS-MOF and the structure had no significant collapse after 1000 cycles. Superior OER activity and excellent stability could ascribed to the fluffy and orderly petal-like structure, which exhibited dispersal of the active sites and facilitated the evolution of oxygen during the catalysis process. The work enriched exploration of heteroatom-doped bimetallic MOFs in energy storage and conversion.

Material anisotropy significantly impacts the mechanical behaviors of asphalt pavements. However, most current asphalt pavement design methods treat the material properties only as isotropic, which could significantly skew the mechanical behaviors. There is a need to evaluate the impact of material anisotropy on pavement mechanical behaviors. In this study, we first developed a new and efficient 3-dimensional finite element (FE) model of anisotropic material. Then, the feasibility of the proposed FE model was verified using field data collected with a falling weight deflectometer. Finally, using this model, the contributions of each layer anisotropy to the mechanical properties were determined. The results showed that the mechanical behaviors were more sensitive to the orthotropy than to the transverse isotropy of the material. The all-layer orthotropy was the most unfavorable combination. In addition, the subgrade orthotropy showed the most significant effect on increasing the surface deflection and compressive strain of the subgrade top (by about 10%). Based on the study results, we recommend that the homogeneity degree of the filling subgrade should be strictly controlled to ensure adequate pavement capacity and anti-rutting performance during construction.

Summary Biotin is an indispensable cofactor in the three domains of life. The unusual virulence factor BioJ of Francisella catalyzes the formation of pimeloyl-ACP, an intermediate in biotin synthesis. Here, we report the 1.58 Å crystal structure of BioJ, the enzymatic activity of which is determined with the in vitro reconstituted reaction and biotin bioassay in vivo. Unlike the paradigm BioH, BioJ displays an atypical α/β-hydrolase fold. A structurally conserved catalytic triad (S151, D248, and H278) of BioJ is functionally defined. A proposed model for BioJ catalysis involves two basic residues-rich cavities, of which cavity-1, rather than cavity-2, binds to the ACP moiety of its physiological substrate, pimeloyl-ACP methyl ester. In summary, this finding provides molecular insights into the BioJ gatekeeper of biotin synthesis., Graphical Abstract, Highlights • BioJ is a distinct gatekeeper of biotin synthesis • We report structural and functional definition of BioJ • We propose a working model for BioJ-substrate binding in addition to catalytic triad • It furthers our understanding how the substrate is gatekept by BioJ in biotin synthesis, Biological Sciences; Microbiology; Structural Biology

The preparation of highly efficient, stable, and low-cost electrocatalysts for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is still a challenge for the development of new energy systems. In this work, a NiCo bimetal loaded on porous carbon (NiCo-C/NF) grown on nickel foam (NF) was obtained via the pyrolysis of a NiCo bimetal MOF (NiCo-MOF/NF) under a nitrogen atmosphere at 500 °C. Compared with NiCo-MOF/NF, NiCo-C/NF had a larger specific surface and uniform mesoporous structure. As an electrocatalyst in the OER, this new type of electrode operated with better stability in an alkaline solution (1.0 mol L−1 KOH), the overpotential when the current density reached 10 mA cm−2 was only 260 mV, and the electrode also exhibited long-term durability in a stability test for 10 h without significant changes. The excellent activity and stability toward the OER can be attributed to the synergistic effect of the NiCo bimetal and the abundant active sites exposed after the carbonization of NiCo-MOF, which compensated for the defect of the insufficient conductivity of the material and promoted the evolution of oxygen in the catalytic process.

Biological motors, ubiquitous in living systems, convert chemical energy into different kinds of mechanical motions critical to cellular functions. Gene product 16 (gp16) in bacteriophage ϕ29 is among the most powerful biomotors known, which adopts a multisubunit ring-shaped structure and hydrolyzes ATP to package double-stranded DNA (dsDNA) into a preformed procapsid. Here we report the crystal structure of the C-terminal domain of gp16 (gp16-CTD). Structure-based alignment and molecular dynamics simulations revealed an essential binding surface of gp16-CTD for prohead RNA, a unique component of the motor complex. Furthermore, our simulations highlighted a dynamic interplay between the N-terminal domain and the CTD of gp16, which may play a role in driving movement of DNA into the procapsid. Lastly, we assembled an atomic structural model of the complete ϕ29 dsDNA packaging motor complex by integrating structural and experimental data from multiple sources. Collectively, our findings provided a refined inchworm-revolution model for dsDNA translocation in bacteriophage ϕ29 and suggested how the individual domains of gp16 work together to power such translocation.

Coronaviruses (CoV) have caused a number of major epidemics in humans and animals, including the current pandemic of coronavirus disease 2019 (COVID-19), which has brought a renewed focus on the evolution and interspecies transmission of coronaviruses. Swine acute diarrhea syndrome coronavirus (SADS-CoV), which was recently identified in piglets in southern China, is an alphacoronavirus that originates from the same genus of horseshoe bats as severe acute respiratory syndrome CoV (SARS-CoV) and that was reported to be capable of infecting cells from a broad range of species, suggesting a considerable potential for interspecies transmission. Given the importance of the coronavirus spike (S) glycoprotein in host range determination and viral entry, we report a cryo-electron microscopy (cryo-EM) structure of the SADS-CoV S trimer in the prefusion conformation at a 3.55-Å resolution. Our structure reveals that the SADS-CoV S trimer assumes an intrasubunit quaternary packing mode in which the S1 subunit N-terminal domain (S1-NTD) and the S1 subunit C-terminal domain (S1-CTD) of the same protomer pack together by facing each other in the lying-down state. SADS-CoV S has several distinctive structural features that may facilitate immune escape, such as a relatively compact architecture of the S trimer and epitope masking by glycan shielding. Comparison of SADS-CoV S with the spike proteins of the other coronavirus genera suggested that the structural features of SADS-CoV S are evolutionarily related to those of the spike proteins of the other genera rather than to the spike protein of a typical alphacoronavirus. These data provide new insights into the evolutionary relationship between spike glycoproteins of SADS-CoV and those of other coronaviruses and extend our understanding of their structural and functional diversity. IMPORTANCE In this article, we report the atomic-resolution prefusion structure of the spike protein from swine acute diarrhea syndrome coronavirus (SADS-CoV). SADS-CoV is a pathogenic alphacoronavirus that was responsible for a large-scale outbreak of fatal disease in pigs and that was reported to be capable of interspecies transmission. We describe the overall structure of the SADS-CoV spike protein and conducted a detailed analysis of its main structural elements. Our results and analyses are consistent with those of previous phylogenetic studies and suggest that the SADS-CoV spike protein is evolutionarily related to the spike proteins of betacoronaviruses, with a strong similarity in S1-NTDs and a marked divergence in S1-CTDs. Moreover, we discuss the possible immune evasion strategies used by the SADS-CoV spike protein. Our study provides insights into the structure and immune evasion strategies of the SADS-CoV spike protein and broadens the understanding of the evolutionary relationships between coronavirus spike proteins of different genera.

Mitochondrial morphology shifts rapidly to manage cellular metabolism, organelle integrity, and cell fate. It remains unknown whether innate nucleic acid sensing, the central and general mechanisms of monitoring both microbial invasion and cellular damage, can reprogram and govern mitochondrial dynamics and function. Here, we unexpectedly observed that upon activation of RIG-I-like receptor (RLR)-MAVS signaling, TBK1 directly phosphorylated DRP1/DNM1L, which disabled DRP1, preventing its high-order oligomerization and mitochondrial fragmentation function. The TBK1-DRP1 axis was essential for assembly of large MAVS aggregates and healthy antiviral immunity and underlay nutrient-triggered mitochondrial dynamics and cell fate determination. Knockin (KI) strategies mimicking TBK1-DRP1 signaling produced dominant-negative phenotypes reminiscent of human DRP1 inborn mutations, while interrupting the TBK1-DRP1 connection compromised antiviral responses. Thus, our findings establish an unrecognized function of innate immunity governing both morphology and physiology of a major organelle, identify a lacking loop during innate RNA sensing, and report an elegant mechanism of shaping mitochondrial dynamics.

The Legionella pneumophila effector MavC is a transglutaminase that carries out atypical ubiquitination of the host ubiquitin (Ub)‐conjugation enzyme UBE2N by catalyzing the formation of an isopeptide bond between Gln40Ub and Lys92UBE2N, which leads to inhibition of signaling in the NF‐κB pathway. In the absence of UBE2N, MavC deamidates Ub at Gln40 or catalyzes self‐ubiquitination. However, the mechanisms underlying these enzymatic activities of MavC are poorly understood at the molecular level. This study reports the structure of the MavC–UBE2N–Ub ternary complex representing a snapshot of MavC‐catalyzed crosslinking of UBE2N and Ub, which reveals the way by which UBE2N–Ub binds to the Insertion and Tail domains of MavC. Based on the structural and experimental data, the catalytic mechanism for the deamidase and transglutaminase activities of MavC is proposed. Finally, by comparing the structures of MavC and MvcA, the homologous protein that reverses MavC‐induced UBE2N ubiquitination, several essential regions and two key residues (Trp255MavC and Phe268MvcA) responsible for their respective enzymatic activities are identified. The results provide insights into the mechanisms for substrate recognition and ubiquitination mediated by MavC as well as explanations for the opposite activity of MavC and MvcA in terms of regulation of UBE2N ubiquitination., The pathogen Legionella pneumophila evades immune detection by deploying the transglutaminase effector MavC to ubiquitinate the host ubiquitin‐conjugating enzyme UBE2N. This work presents the structure of MavC–UBE2N–Ub ternary complex and sheds light on the molecular basis for MavC‐induced transglutamination and its mechanistic differences with its homolog MvcA, which counteracts MavC activity by deubiquitinating modified UBE2N in later phases of infection.

Spring viremia of carp virus (SVCV) is a highly pathogenic Vesiculovirus in the common carp. The phosphoprotein (P protein) of SVCV is a multifunctional protein that acts as a polymerase cofactor and an antagonist of cellular interferon (IFN) response. Here, we report the 1.5-Å-resolution crystal structure of the P protein central domain (P(CD)) of SVCV (SVCV(PCD)). The P(CD) monomer consists of two β sheets, an α helix, and another two β sheets. Two P(CD) monomers pack together through their hydrophobic surfaces to form a dimer. The mutations of residues on the hydrophobic surfaces of P(CD) disrupt the dimer formation to different degrees and affect the expression of host IFN consistently. Therefore, the oligomeric state formation of the P protein of SVCV is an important mechanism to negatively regulate host IFN response. IMPORTANCE SVCV can cause spring viremia of carp with up to 90% lethality, and it is the homologous virus of the notorious vesicular stomatitis virus (VSV). There are currently no drugs that effectively cure this disease. P proteins of negative-strand RNA viruses (NSVs) play an essential role in many steps during the replication cycle and an additional role in immunosuppression as a cofactor. All P proteins of NSVs are oligomeric, but the studies on the role of this oligomerization mainly focus on the process of virus transcription or replication, and there are few studies on the role of P(CD) in immunosuppression. Here, we present the crystal structure of SVCV(PCD). A new mechanism of immune evasion is clarified by exploring the relationship between SVCV(PCD) and host IFN response from a structural biology point of view. These findings may provide more accurate target sites for drug design against SVCV and provide new insights into the function of NSV(PCD).

The proliferation and migration of vascular smooth muscle cells (VSMCs) are involved in the pathogenesis of intracranial aneurysm (IA) formation and rupture. Interleukin enhancer binding factor 2 (ILF2) is known as the nuclear factor of activated T cells and regulates cell growth. This study was aimed to explore the effects of ILF2 on IA progression. Human brain VSMCs (hBVSMCs) were transfected with pCDNA3.1(+), pCDNA3.1(+)-ILF2, siRNA-negative control, and siRNA-ILF2. The transfection efficiency was then evaluated by determining ILF2 expression. The cell viability and apoptosis were determined using Cell Counting Kit-8 and Annexin V-FITC cell apoptosis assay kit, respectively. Real-time quantification PCR (RT-qPCR) was applied to measure the expression levels of apoptosis-related and inflammation-related genes. Finally, western blot was used to detect the expression level of Fas cell surface death receptor 95 (CD95) and Caspase 8. Overexpression of ILF2 could significantly increase cell viability and decrease cell apoptosis (P

The current outbreak of Coronavirus Disease 2019 (COVID-19) by a novel betacoronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has aroused great public health concern. Coronavirus has a history of causing epidemics in human and animals. In 2017 an outbreak in piglets by a novel coronavirus was emerged designated as swine acute diarrhea syndrome coronavirus (SADS-CoV) which is originated from the same genus of horseshoe bats (Rhinolophus) as Severe Acute Respiratory Syndrome CoV (SARS-CoV) having a broad species tropism. In addition to human cells, it can also infect cell lines from diverse species. Coronavirus host range is determined by its spike glycoprotein (S). Given the importance of S protein in viral entry to cells and host immune responses, here we report the cryo-EM structure of the SADS-CoV S in the prefusion conformation at a resolution of 3.55 Å. Our study reveals that SADS-CoV S structure takes an intra-subunit quaternary packing mode where the NTD and CTD from the same subunit pack together by facing each other. The comparison of NTD and CTD with that of the other four genera suggests the evolutionary process of the SADS-CoV S. Moreover, SADS-CoV S has several characteristic structural features, such as more compact architecture of S trimer, and masking of epitopes by glycan shielding, which may facilitate viral immune evasion. These data provide new insights into the evolutionary relationships of SADS-CoV S and would extend our understanding of structural and functional diversity, which will facilitate to vaccine development.

The Legionella pneumophila effector MavC induces ubiquitination of the E2 ubiquitin‐conjugating enzyme UBE2N by transglutamination, thereby abolishing its function in the synthesis of K(63)‐type polyubiquitin chains. The inhibition of UBE2N activity creates a conundrum because this E2 enzyme is important in multiple signaling pathways, including some that are important for intracellular L. pneumophila replication. Here, we show that prolonged inhibition of UBE2N activity by MavC restricts intracellular bacterial replication and that the activity of UBE2N is restored by MvcA, an ortholog of MavC (50% identity) with ubiquitin deamidase activity. MvcA functions to deubiquitinate UBE2N‐Ub using the same catalytic triad required for its deamidase activity. Structural analysis of the MvcA‐UBE2N‐Ub complex reveals a crucial role of the insertion domain in MvcA in substrate recognition. Our study establishes a deubiquitination mechanism catalyzed by a deamidase, which, together with MavC, imposes temporal regulation of the activity of UBE2N during L. pneumophila infection.

Intracranial aneurysm (IA) is a devastating disease, the pathogenesis of which remains to be elucidated. The present study aimed to determine the molecular mechanism of IA and to identify potential therapeutic targets using bioinformatics analysis. The GSE54083 dataset, which includes data from patients with ruptured IA and superficial temporal artery controls, was downloaded from the Gene Expression Omnibus, and differentially expressed genes (DEGs) were identified in the ruptured IA samples using the limma package in R. Subsequently, the Database for Annotation, Visualization and Integrated Discovery software was used to perform function and pathway enrichment analyses and the Search Tool for the Retrieval of Interacting Genes database was used to construct the protein‑protein interaction (PPI) network. Then, microRNA (miRNA) target and transcription factor (TF) target pairs were identified using the miR2Disease, MiRwalk2, ITFP and TRANSFAC databases. Finally, an integrated network of TF‑target‑miRNAs was constructed using Cytoscape. A total of 402 upregulated DEGs and 375 downregulated DEGs were identified from the ruptured IA samples compared with the superficial temporal artery samples. The majority of the upregulated DEGs were significantly enriched in the immune system development category, including CD40 ligand (CD40LG) and CD40 and the downregulated DEGs, such as striatin (STRN), were enriched in neuron projection development. In addition, nitric oxide synthase 1 (NOS1), a target of miRNA‑125b, and myosin heavy chain 11 (MYH11), a target of minichromosome maintenance complex component 4 (MCM4), had higher degree scores in the integrated network. These findings suggest that CD40, CD40LG, NOS1, STRN, MCM4, MYH11 and miR‑125b may be potential therapeutic targets for the treatment of IA.

The preparation of high-efficiency, stable and low-cost oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalysts is always a challenge for new energy systems. In this work, a simple hydrothermal synthesis method was used to obtain FeMn bimetallic organic materials (FeMn-MOF/NF) grown on foamed nickel (NF) in one step. Moreover, FeMn-MOF/NF(1:1) had larger electrochemical specific surface area and unique nano-flower-like structure. The overpotentials of OER and HER in alkaline solution at a current density of 50 mA·cm−2 were 290 mV and 260 mV, respectively, and the total water splitting potential at this current density is only 1.7 V. The excellent activity and stability were attributed to the synergistic effect of FeMn. The bimetal and abundant active sites could promote the release of oxygen during the catalytic process.

Nickel-based nanowire arrays with different cobalt content were prepared via a modified template-assisted electrodeposition method for hydrogen evolution reaction. The experimental results proved that, compared with samples of other ratios, the nanowire arrays with a nickel-cobalt atomic ratio of 32:1 exhibited better hydrogen evolution performance, and an overpotential of 103 mV was required to obtain a current density of 10mA cm−2, while the nanowire arrays with a ratio of nickel-cobalt of 3:1 required an overpotential of 171 mV to achieve the same current density. The density functional theory (DFT) calculations performed were consistent with the experimental results that Ni-based materials doped with 1Co had better electrocatalytic activity than those doped with 2Co. The excellent hydrogen evolution performance of catalyst was attributed to the synergy between nickel and cobalt atoms and the nanowire structure increased the specific surface area exposing more active sites for hydrogen adsorption and adsorption.

Interferon (IFN) is a vital antiviral factor in host in the early stages after the viral invasion. Meanwhile, viruses have to survive by taking advantage of the cellular machinery and complete their replication. As a result, viruses evolved several immune escape mechanisms to inhibit host IFN expression. However, the mechanisms used to escape the host's IFN system are still unclear for infectious hematopoietic necrosis virus (IHNV). In this study, we report that the N protein of IHNV inhibits IFN1 production in rainbow trout by degrading the MITA. Firstly, the upregulation of IFN1 promoter activity stimulated by poly I:C was suppressed by IHNV infection. Consistent with this result, the overexpression of the N protein of IHNV blocked the IFN1 transcription that was activated by poly I:C and MITA. Secondly, MITA was remarkably decreased by the overexpression of N protein at the protein level. Further analysis demonstrated that the N protein targeted MITA and promoted the ubiquitination of MITA. Taken together, these data suggested that the production of rainbow trout IFN1 could be suppressed by the N protein of IHNV via degrading MITA.

Proteasomes are highly abundant and conserved protease complexes that eliminate unwanted proteins in the cells. As a single-chain ATP-independent nuclear proteasome activator, proteasome activator 200 (PA200) associates with 20S core particle to form proteasome complex that catalyzes polyubiquitin-independent degradation of acetylated histones, thus playing a pivotal role in DNA repair and spermatogenesis. Here, we present cryo–electron microscopy (cryo-EM) structures of the human PA200-20S complex and PA200 at 2.72 Å and 3.75 Å, respectively. PA200 exhibits a dome-like architecture that caps 20S and uses its C-terminal YYA (Tyr-Tyr-Ala) to induce the α-ring rearrangements and partial opening of the 20S gate. Our structural data also indicate that PA200 has two openings formed by numerous positively charged residues that respectively bind (5,6)-bisdiphosphoinositol tetrakisphosphate (5,6[PP]2-InsP4) and inositol hexakisphosphate (InsP6) and are likely to be the gates that lead unfolded proteins through PA200 and into the 20S. Besides, our structural analysis of PA200 found that the bromodomain (BRD)-like (BRDL) domain of PA200 shows considerable sequence variation in comparison to other human BRDs, as it contains only 82 residues because of a short ZA loop, and cannot be classified into any of the eight typical human BRD families. Taken together, the results obtained from this study provide important insights into human PA200-induced 20S gate opening for substrate degradation and the opportunities to explore the mechanism for its recognition of H4 histone in acetylation-mediated proteasomal degradation., Proteasomes are highly abundant and conserved protease complexes that eliminate unwanted proteins in the cells. The cryo-EM structures of PA200 and the PA200-20S proteasome complex reveal two openings on PA200 which bind inositol phosphates as cofactors, and novel insights into PA200-induced gate-opening of 20S.

Poliovirus (PV) 2CATPase is the most studied 2C protein in the Picornaviridae family. It is involved in RNA replication, encapsidation and uncoating and many inhibitors have been found that target PV 2CATPase. Despite numerous investigations to characterize its functions, a high-resolution structure of PV 2C has not yet been determined. We report here the crystal structure of a soluble fragment of PV 2CATPase to 2.55Å, containing an ATPase domain, a zinc finger and a C-terminal helical domain but missing the N-terminal domain. The ATPase domain shares the common structural features with EV71 2C and other Superfamily 3 helicases. The C-terminal cysteine-rich motif folds into a CCCC type zinc finger in which four cysteine ligands and several auxiliary residues assist in zinc binding. By comparing with the known zinc finger fold groups, we found the zinc finger of 2C proteins belong to a new fold group, which we denote the “Enterovirus 2C-like” group. The C-terminus of PV 2CATPase forms an amphipathic helix that occupies a hydrophobic pocket located on an adjacent PV 2CATPase in the crystal lattice. The C-terminus mediated PV 2C-2C interaction promotes self-oligomerization, most likely hexamerization, which is fundamental to the ATPase activity of 2C. The zinc finger is the most structurally diverse feature in 2C proteins. Available structural and virological data suggest that the zinc finger of 2C might confer the specificity of interaction with other proteins. We built a hexameric ring model of PV 2CATPase and visualized the previously identified functional motifs and drug-resistant sites, thus providing a structure framework for antiviral drug development., Author summary Since the launch of the Global Polio Eradication Initiative, the number of poliomyelitis cases has significantly reduced but obstacles to disease eradication remain. In the endgame phase, anti-poliovirus drugs will be critical in controlling transmission of vaccine-derived polioviruses and in treating patients with chronic infection. However, no effective anti-poliovirus drugs are yet available. The 2CATPase encoded by poliovirus is one of the most important drug targets, and many inhibitors of 2C have been found. We report here the crystal structure of a soluble portion of PV 2CATPase, containing an ATPase domain, a zinc finger and a C-terminal helical domain. Our findings not only revealed common and individual structural features in the picornaviral 2C protein family, but also allowed us to visualize a large collection of functional motifs and drug-resistant sites identified from the decades-long investigations of poliovirus 2CATPase. Our findings are invaluable for understanding the function of picornavirus 2C proteins and the development of antiviral drugs.

Human coronavirus (CoV) HKU1 is a pathogen causing acute respiratory illnesses and so far little is known about its biology. HKU1 virus uses its S1 subunit C-terminal domain (CTD) and not the N-terminal domain like other lineage A β-CoVs to bind to its yet unknown human receptor. Here we present the crystal structure of HKU1 CTD at 1.9 Å resolution. The structure consists of three subdomains: core, insertion and subdomain-1 (SD-1). While the structure of the core and SD-1 subdomains of HKU1 are highly similar to those of other β-CoVs, the insertion subdomain adopts a novel fold, which is largely invisible in the cryo-EM structure of the HKU1 S trimer. We identify five residues in the insertion subdomain that are critical for binding of neutralizing antibodies and two residues essential for receptor binding. Our study contributes to a better understanding of entry, immunity and evolution of CoV S proteins., Human coronavirus HKU1 can cause severe respiratory diseases in young children and immunocompromised patients. Here, the authors present the structure of the C-terminal domain of the viral spike glycoprotein S1 subunit, which is important for host cell receptor binding.

Structure of EV71 2C unveils the structural basis of the functional mechanism of carboxyl terminus–mediated self-oligomerization., Enterovirus 71 (EV71) is the major pathogen responsible for outbreaks of hand, foot, and mouth disease. EV71 nonstructural protein 2C participates in many critical events throughout the virus life cycle; however, its precise role is not fully understood. Lack of a high-resolution structure made it difficult to elucidate 2C activity and prevented inhibitor development. We report the 2.5 Å–resolution crystal structure of the soluble part of EV71 2C, containing an adenosine triphosphatase (ATPase) domain, a cysteine-rich zinc finger with an unusual fold, and a carboxyl-terminal helical domain. Unlike other AAA+ ATPases, EV71 2C undergoes a carboxyl terminus–mediated self-oligomerization, which is dependent on a specific interaction between the carboxyl-terminal helix of one monomer and a deep pocket formed between the ATPase and the zinc finger domains of the neighboring monomer. The carboxyl terminus–mediated self-oligomerization is fundamental to 2C ATPase activity and EV71 replication. Our findings suggest a strategy for inhibition of enterovirus replication by disruption of the self-oligomerization interface of 2C.

First, the axle-load skid-resistance conversion formula of asphalt pavement was established in accordance with the equivalent principle of skid-resistance performance attenuation which is similar to the way of axle-load equivalent conversion for asphalt pavements structure design. The way to determine the axle number coefficient and wheel number coefficient was also proposed. Second, the prediction method of skid-resistance life of asphalt pavement was put forward on the basis of the axle-load skid-resistance equivalent conversion formula. Afterwards, the skid-resistance performance attenuation tests for asphalt mixture SMA16 were carried out on a selected expressway under various wheel pressures. Finally, by using the deduction of fatigue equation of asphalt mixture for reference, the skid-resistance fatigue equation for SMA16 based on BPN value was derived to predict the skid-resistance life of the expressway pavement. The results indicate that it is feasible to study skid-resistance performance...

Intracranial aneurysm (IA) is a localized dilation of the blood vessel. The present study was designed to explore the mechanisms of rupture of IA. GSE13353 (including 11 ruptured and 8 unruptured IA samples) and GSE15629 (including 8 ruptured and 6 unruptured IA samples) were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) identified using limma and MetaDE packages were merged, and a protein-protein interaction (PPI) network analysis was performed using Cytoscape software. Pathway enrichment analysis was performed for the nodes of the PPI network using the fisher algorithm. The 100 most prominent genes in the network were designated candidate genes and a hierarchical clustering analysis was performed. The tune.svm function of e1071 package was used to construct a support vector machine (SVM) classifier, and the Candidate Cancer Gene Database was applied to analyze the characterization of gene-associated cancer. Furthermore, the genes involved in the SVM classifier were assessed via principal component analysis (PCA). In the ruptured samples, 1,292 DEGs and 1,029 DEGs separately were identified by limma and MetaDE packages. The 100 most prominent genes in the network included fibronectin 1 (FN1), amyloid β (A4) precursor protein (APP), nuclear RNA export factor 1 (NXF1) and signal transducer and activator of transcription 3 (STAT3). Pathway enrichment analysis identified that toll-like receptor 3 (TLR3) was enriched in the Toll-like receptor signaling pathway. A total of 15 genes (including FN1) were used to construct the SVM classifier. NXF1 was identified to be associated with Nervous System Cancer. PCA revealed that APP, NXF1 and STAT3 were the 3 principal components. TLR3, FN1, APP, NXF1 and STAT3 may affect the rupture of IA.

Vehicles move on asphalt pavements repeatedly at high frequency and the stress due to temperature changing also acts on asphalt pavements repeatedly at low frequency. Many defining ways on fatigue damage have been used to study fatigue damage developing law of asphalt mixtures. But comprehensive comparing should be done between different fatigue damage defining ways. Laboratory low frequency fatigue tests and high frequency fatigue tests of asphalt mixtures were developed with Material Test System (MTS-810). The damage developing laws within fatigue life of asphalt mixtures were analyzed respectively with fatigue damage defining ways based on strain amplitude, residual strain, dynamic modulus and dissipated energy. The results show that fatigue damage developing process based on different defining ways are different from each other and the critical damage values are also different from each other. The analyzing results show that the fatigue damage developing curve based on dissipated energy defining way is quite distinct from the others. So it is best to define fatigue damage with dissipated energy and fatigue damage defining ways based on strain amplitude, residual strain, dynamic modulus are not appropriate to express fatigue damage.

The effects of fiber modifiers on the performance of asphalt mixtures were investigated. Cellulose fiber, polyester fiber, and basalt mineral fiber were adopted as modifiers, and the dynamic modulus test, indirect tension fatigue test, and wheel track test were conducted in order to study the properties of asphalt mixtures containing various fibers. The test results indicate that the viscoelastic property of asphalt mixtures can be improved by the addition of fiber modifiers, which resulted in an increase of the dynamic modulus and a reduction in the phase angle. Dynamic modulus master curves also confirmed that fiber addition caused a general increase in the dynamic modulus for all mixtures evaluated within the range of the loading frequency, especially at low frequencies. The fatigue property and rutting resistance of fiber modified asphalt mixtures could be enhanced significantly.