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Thogotoviruses are important zoonotic viruses infecting a variety of domestic animals, as well as humans. Among these viruses, Bourbon virus (BRBV) is one of the several human-infecting members, which emerged in the US in recent years and caused human deaths. Here, we report the crystal structure of the BRBV envelope glycoprotein in the postfusion conformation. The structure adopts the typical fold of a class III viral fusion protein and displays an extensive positively charged electrostatic potential pattern, which resembles the glycoprotein of Dhori virus and is consistent with our previous predictions. In addition, compared to other previously defined class III viral fusion proteins, the structures of all thogotovirus glycoproteins and homologs are more similar to herpes virus glycoprotein Bs than to the rhabdovirus G proteins. Thus, class III viral fusion proteins are quite diverse in structure, and sub-classes may have developed during evolution. [ABSTRACT FROM AUTHOR]

Accumulating evidence indicates that MERS-CoV originated from bat coronaviruses (BatCoVs). Previously, we demonstrated that both MERS-CoV and BatCoV HKU4 use CD26 as a receptor, but how the BatCoVs evolved to bind CD26 is an intriguing question. Here, we solved the crystal structure of the S1 subunit C-terminal domain of HKU5 (HKU5-CTD), another BatCoV that is phylogenetically related to MERS-CoV but cannot bind to CD26. We observed that the conserved core subdomain and those of other betacoronaviruses (betaCoVs) have a similar topology of the external subdomain, indicating the same ancestor of lineage C betaCoVs. However, two deletions in two respective loops located in HKU5-CTD result in conformational variations in CD26-binding interface and are responsible for the non-binding of HKU5-CTD to CD26. Combined with sequence variation in the HKU5-CTD receptor binding interface, we propose the necessity for surveilling the mutation in BatCoV HKU5 spike protein in case of bat-to-human interspecies transmission. [ABSTRACT FROM AUTHOR]

Influenza viruses cause seasonal flu each year and pandemics or epidemic sporadically, posing a major threat to public health. Recently, a new influenza D virus (IDV) was isolated from pigs and cattle. Here, we reveal that the IDV utilizes 9-O-acetylated sialic acids as its receptor for virus entry. Then, we determined the crystal structures of hemagglutinin-esterase-fusion glycoprotein (HEF) of IDV both in its free form and in complex with the receptor and enzymatic substrate analogs. The IDV HEF shows an extremely similar structural fold as the human-infecting influenza C virus (ICV) HEF. However, IDV HEF has an open receptor-binding cavity to accommodate diverse extended glycan moieties. This structural difference provides an explanation for the phenomenon that the IDV has a broad cell tropism. As IDV HEF is structurally and functionally similar to ICV HEF, our findings highlight the potential threat of the virus to public health. [ABSTRACT FROM AUTHOR]

The receptor-binding specificity of influenza A viruses is a major determinant for the host tropism of the virus, which enables interspecies transmission. In 2013, the first human case of infection with avian influenza A (H6N1) virus was reported in Taiwan. To gather evidence concerning the epidemic potential of H6 subtype viruses, we performed comprehensive analysis of receptor-binding properties of Taiwan-isolated H6 HAs from 1972 to 2013. We propose that the receptor-binding properties of Taiwan-isolated H6 HAs have undergone three major stages: initially avian receptor-binding preference, secondarily obtaining human receptor-binding capacity, and recently human receptor-binding preference, which has been confirmed by receptor-binding assessment of three representative virus isolates. Mutagenesis work revealed that E190V and G228S substitutions are important to acquire the human receptor-binding capacity, and the P186L substitution could reduce the binding to avian receptor. Further structural analysis revealed how the P186L substitution in the receptor-binding site of HA determines the receptor-binding preference change. We conclude that the human-infecting H6N1 evolved into a human receptor preference. [ABSTRACT FROM AUTHOR]

Short-chain pentraxins (PTXs), including CRP and SAP, are innate pattern recognition receptors that play vital roles in the recognition and elimination of various pathogenic bacteria by triggering the classical complement pathway through C1q. Similar to antibodies, pentraxins can also activate opsonisation and phagocytosis by interacting with Fc receptors (FcRs). Various structural studies on human PTXs have been performed, but there are no reports about the crystal structure of bony fish pentraxins. Here, the crystal structures of zebrafish PTX ( Dare -PTX-Ca and Dare -PTX) are presented. Both Dare -PTX-Ca and Dare -PTX are cyclic trimers, which are new forms of crystallised pentraxins. The structures reveal that the ligand-binding pocket (LBP) in the recognition face of Dare -PTX is deep and narrow. Homology modelling shows that LBPs from different Dare -PTX loci differ in shape, reflecting their specific recognition abilities. Furthermore, in comparison with the structure of hCPR, a new C1q binding mode was identified in Dare -PTX. In addition, the FcR-binding sites of hSAP are partially conserved in Dare -PTX. These results will shed light on the understanding of a primitive PTX in bony fish, which evolved approximately 450 million years ago. [ABSTRACT FROM AUTHOR]

Interferon gamma (IFN-γ) is an important cytokine that induces antiviral, antiproliferative, and immunomodulatory effects on target cells, and is also crucial in the early defense against intracellular parasites, such as Listeria monocytogenes and Toxoplasma gondii. The biological activity of IFN-γ relies upon the formation of a complex with its 2 receptors, the interferon gamma alpha chain (IFNGR1) and beta chain (IFNGR2), which are type II cytokine receptors. Structural models of ligand-receptor interaction and complex structure of chicken IFNs with their receptors have remained elusive. Here we report the first structure of Gallus gallus (chicken) IFNGR1 (chIFNGR1) at 2.0 Å by molecule replacement according to the structure of selenomethionine substituted chIFNGR1. The structural comparison reveals its structural similarities with other class II cytokine receptors, despite divergent primary sequences. We further investigate the ligand-receptor interaction properties of chicken IFN-γ (chIFN-γ) and chIFNGR1 using size-exclusion chromatography and surface plasmon resonance techniques. These data aid in the understanding of the interaction of chicken (avian) IFN-γ with its receptors and its signal transduction. [ABSTRACT FROM AUTHOR]

The controlling path and controlling segment are the basis for repetitive project scheduling. In this paper the controlling path is defined as the longest path in duration that determines the minimum project duration, including the controlling segments and controlling constraints on it. The controlling segments are defined as the subactivities on the controlling path. A method to identify the controlling path and controlling segments is proposed, on the basis of the technology of identifying the potential controlling points. To investigate how the project duration is determined, three types of controlling segments are defined and analyzed, namely, the forward controlling segment, the point controlling segment, and the backward controlling segment. This paper presents a convenient and correct way to identify the controlling path and controlling segments conforming to the constraints of projects. [ABSTRACT FROM AUTHOR]

C-reactive protein (CRP) is an acute phase protein that is found in blood, the concentration of which in plasma rises rapidly in response to inflammation. It functions as a pattern-recognition molecule, recognizing dead cells and various pathogenic agents and eliminating them by utilizing the classical complement pathway and activating macrophages. CRP is phylogenetically highly conserved in invertebrates and mammals. To date, information on the CRP gene has been reported from numerous species of animals, but little is known about the structure of CRP from species other than humans. In order to solve the structure of CRP from bony fish, the CRP gene from zebrafiah ( Danio rerio) was cloned and expressed in Escherichia coli. The zebrafish CRP ( Dare-CRP) was then purified and crystallized. The crystal diffracted to 2.3 Å resolution and belonged to space group R3, with unit-cell parameters a = b = 114.7, c = 61.0 Å. The Matthews coefficient and solvent content were calculated to be 3.28 Å3 Da−1 and 62.55%, respectively. Determination of the zebrafish CRP structure should be helpful in investigating the evolution of CRPs in the innate immune system. [ABSTRACT FROM AUTHOR]

Abstract: The human CD8 functions as a co-receptor for specific T cell recognition, and only one complex structure of human CD8αα binding to HLA-A*0201 has been solved, revealing the molecular basis of CD8 interacting with its ligand pHLA. Here, we present the complex structures of human CD8αα bound to HLA-A*2402, which demonstrate two opposite α3 domain CD loop shifts (either pull or push) in the HLA heavy chain upon CD8 engagement. Taking the previously reported mouse CD8–pMHC complex structures into account, from the structural view, all of the data indicate the plasticity of CD8 binding to pMHC/HLA, which facilitates its co-receptor function for T cells. The plasticity of CD8 binding appears not to affect the specificity of TCR recognition, as no peptide conformation change extends to the pMHC interface for TCR contacting. [Copyright &y& Elsevier]

CD8αα homodimers or CD8αβ heterodimers form on the T-cell surface, where they are essential as co-receptors for MHC class I molecules in activation of the CTL response. To date, swine have been found to show the highest percentage of lymphocytes with surface expression of CD8α. Crystallographic analysis of swine CD8α (sCD8α) to 1.8 Å resolution revealed that the crystals belonged to space group P3221, with unit-cell parameters a = 80.97, b = 80.97, c = 95.19 Å. The Matthews coefficient and the solvent content were calculated to be 3.23 Å3 Da−1 and 61.89%, respectively. These results may aid further structural and functional analyses of sCD8α. [ABSTRACT FROM AUTHOR]

Abstract: This paper firstly presents an overview of wind energy potential in China and discusses the features of small wind power system deployment. Then it reviews the current status of small wind power development in China. The future perspectives of and barriers to small wind power development in China are predicted and analyzed. Finally some policies for promoting small wind power development in China are recommended. This study provides a comprehensive overview of the current status of small wind power in China and some insights into the prospects of small wind power market in China. [Copyright &y& Elsevier]

In order to illustrate the structure of the swine MHC class I (SLA-I) molecule and to evaluate the cytotoxic T lymphocyte (CTL) response against porcine reproductive and respiratory syndrome virus (PRRSV), the ternary complex of the SLA-I molecule termed SLA-1*1502 with β2-microglobulin and the CTL epitope TMPPGFELY (PRRSV-NSP9TY9) derived from PRRSV nonstructural protein 9 (residues 198-206) was assembled and crystallized. The crystal diffracted X-rays to 2.2 Å resolution and belonged to space group P212121, with unit-cell parameters a = 66.1, b = 74.1, c = 98.6 Å; it contained one molecule in the asymmetric unit. The Matthews coefficient and the solvent content were calculated to be 2.74 Å3 Da−1 and 55.17%, respectively. The results will be helpful in obtaining insight into the structural basis of the presentation of viral epitopes by SLA-I. [ABSTRACT FROM AUTHOR]

Presents the results of research on the secondary structures of proteins. The two classes: regular structure and nonregular structure; Defining of helices and sheets as "regular" structures because their residues, which have repeating main-chain torsion angles; Arrangement of the backbone N-H and C-O groups in a periodic pattern of hydrogen bonding; Nonregular secondary structures having nonrepeating backbone torsion angles; Sequence analysis of nonregular secondary structures; Indication that these nonregular parts can be predicted by wavelet analysis.

A recombinant form of cyclic imide hydrolase from Pseudomonas putida YZ-26 has been crystallized by the hanging-drop method. X-ray diffraction data were collected to 1.9 Å resolution. The crystals belonged to the orthorhombic space group C2221, with unit-cell parameters a = 111.91, b = 176.04, c = 176.06 Å. Assuming the presence of four molecules in the asymmetric unit gives a VM value of 3.10 Å3 Da−1 and a solvent content of 60.31%. [ABSTRACT FROM AUTHOR]

Nectin-2 belongs to a family of immunoglobulin-like cell adhesion molecules that are characterized by the presence of three immunoglobulin-like domains (V, C2 and C2) in the extracellular region. The V domain plays important roles in cell adhesion, NK cell activation and the entry of some herpesvirus. In this study, the V domain of human nectin-2 was expressed in Escherichia coli in the form of inclusion bodies, which were subsequently denatured and refolded. The soluble protein was crystallized using the hanging-drop vapour-diffusion method. The crystals diffracted to 1.85 Å resolution and belonged to space group P21, with unit-cell parameters a = 52.3, b = 43.9, c = 56.1 Å, β = 118.2°. [ABSTRACT FROM AUTHOR]

Alanine racemase (DadXOF4), a dimeric endogenous PLP-dependent alkaline enzyme from alkaliphilic Bacillus pseudofirmus OF4, was expressed in Escherichia coli and purified with a His6 tag in a form suitable for X-ray crystallographic analysis. Crystals were grown by the hanging-drop vapour-diffusion method at 291 K using a solution containing 1.4 M sodium/potassium phosphate pH 8.2. The protein crystallized in space group P212121, with two protein molecules in the asymmetric unit. [ABSTRACT FROM AUTHOR]

Protective vaccines are crucial for preventing and controlling coronavirus disease 2019 (COVID-19). Updated vaccines are needed to confront the continuously evolving and circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. These vaccines should be safe, effective, amenable to easily scalable production, and affordable. Previously, we developed receptor binding domain (RBD) dimer-based protein subunit vaccines (ZF2001 and updated vaccines) in mammalian cells. In this study, we explored a strategy for producing RBD-dimer immunogens in Pichia pastoris. We found that wild-type P. pastoris produced hyperglycosylated RBD-dimer protein containing four N-glycosylation sites in P. pastoris. Therefore, we engineered the wild type P. pastoris (GS strain) into GSΔOCH1pAO by deleting the OCH1 gene (encoding α-1,6-mannosyltransferase enzyme) to decrease glycosylation, as well as by overexpressing the HIS4 gene (encoding histidine dehydrogenase) to increase histidine synthesis for better growth. In addition, RBD-dimer protein was truncated to remove the R328/F329 cleavage sites in P. pastoris. Several homogeneous RBD-dimer proteins were produced in the GSΔOCH1pAO strain, demonstrating the feasibility of using the P. pastoris expression system. We further resolved the cryo-EM structure of prototype-Beta RBD-dimer complexed with the neutralizing antibody CB6 to reveal the completely exposed immune epitopes of the RBDs. In a murine model, we demonstrated that the yeast-produced RBD-dimer induces robust and protective antibody responses, which is suitable for boosting immunization. This study developed the yeast system for producing SARS-CoV-2 RBD-dimer immunogens, providing a promising platform and pipeline for the future continuous updating and production of SARS-CoV-2 vaccines. Author summary: SARS-CoV-2 continuously circulates, resulting in infections and re-infections globally. COVID-19 vaccines can provide protection against disease and death caused by SARS-CoV-2. However, the immune responses induced by vaccination will wane gradually. In addition, new SARS-CoV-2 sub-variants emerge and show immune evasion. Therefore, inoculating with the updated COVID-19 vaccines is recommended for enhancing protection against the circulating SARS-CoV-2 sub-variants. Pichia pastoris is an eukaryotic system that enables fast and low-cost producing proteins with easy scale-up. In this study, we developed a strategy for producing SARS-CoV-2 RBD-dimer immunogens in glycoengineered Pichia pastoris with homogeneous glycosylation and high stability. The RBD antigen can be updated with the sequence of circulating sub-variants. In addition, mouse experiments demonstrated that the yeast-produced RBD-dimer vaccines induced robust and protective immune responses. This study provides a simple and promising approach to produce yeast-derived SARS-CoV-2 RBD-dimers as a boosting vaccine and guides the basis for the production of the other vaccines in Pichia pastoris. [ABSTRACT FROM AUTHOR]

The widely used rotavirus (RV) vaccine, Rotateq, contained reassortment strains of human and bovine G1/2/3/4P[5] RVs. The functional and structural features of bovine G1P[5] VP8* were investigated. Bovine G1P[5] VP8* was identified to interact with sialic acids and sialic acid-containing glycans. In addition, P[5] VP8* recognized α-Gal histo-blood group antigens (HBGAs). Bovine G1P[5] VP8* did not hemagglutinate the tested red blood cells. The crystal structure of P[5] VP8* was determined at 1.7 Å. Structural superimposition revealed that P[5] VP8* was most close to human P[8] VP8*, while much further to VP8*s of porcine P[7] and rhesus P[3]. Sequence alignment showed that amino acids of the putative glycan binding site in P[5] VP8* were different to those in P[3]/P[7] VP8*s, indicating that P[5] VP8* may interact with glycans using different mechanism. This study provided more understanding of P[5] RV infection and the interactions of RV VP8* and glycans. • Bovine G1P[5] WI79-9 VP8* bound to sialic acids (SA) and SA-glycans according to the glycan binding assays. • Bovine G1P[5] VP8* recognized αGal histo-blood group antigens, such as αGal trisaccharide. • Crystal structure of bovine G1P[5] RV VP8* was determined and P[5] VP8* was most close to P[8] VP8* but not to P[3] VP8*. • P[5] VP8* possessed various amino acids compared to other VP8*and may interact with the glycans by different pattern. [ABSTRACT FROM AUTHOR]

Since SARS-CoV-2 Omicron variant emerged, it is constantly evolving into multiple sub-variants, including BF.7, BQ.1, BQ.1.1, XBB, XBB.1.5 and the recently emerged BA.2.86 and JN.1. Receptor binding and immune evasion are recognized as two major drivers for evolution of the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein. However, the underlying mechanism of interplay between two factors remains incompletely understood. Herein, we determined the structures of human ACE2 complexed with BF.7, BQ.1, BQ.1.1, XBB and XBB.1.5 RBDs. Based on the ACE2/RBD structures of these sub-variants and a comparison with the known complex structures, we found that R346T substitution in the RBD enhanced ACE2 binding upon an interaction with the residue R493, but not Q493, via a mechanism involving long-range conformation changes. Furthermore, we found that R493Q and F486V exert a balanced impact, through which immune evasion capability was somewhat compromised to achieve an optimal receptor binding. We propose a "two-steps-forward and one-step-backward" model to describe such a compromise between receptor binding affinity and immune evasion during RBD evolution of Omicron sub-variants. Synopsis: SARS-CoV-2 evolution leads to the rapid and continuous emergence of sub-variants. This study identifies key amino acids which mediate sub-variant infection potential by balancing host receptor binding affinity and immune escape. The cryo-EM structures of the receptor binding domains (RBDs) of Omicron sub-variants BF.7, BQ.1, BQ.1.1, XBB and XBB.1.5 in complex with human ACE2 were determined. R346T substitution enhances ACE2 binding via an interplay with R493, but not Q493 substitution, due to long-range conformation alterations. The mutations R493Q and F486V maintain an optimal receptor binding affinity of the RBD, while R493Q reduces immune evasion capability. Cryo-EM structures of Omicron sub-variant receptor binding domains with human ACE2 receptor reveal the key residues that balance receptor binding and immune evasion potential. [ABSTRACT FROM AUTHOR]

Rotavirus (RV) is a common cause of acute gastroenteritis in young children. While P[8] and P[4] are the most prevalent RV genotypes in humans, other genotypes are also reported in human infections occasionally, including human P[25]. The glycan binding and structural characteristics of human P[25] were explored in our study. Human P[25] VP8* recognized type A histo-blood group antigen (HBGA) in the glycan microarray/oligosaccharide binding assay and could specifically hemagglutinate type A blood cells. Moreover, the P[25] VP8* structure was determined at 2.6 Å, revealing a similar conformation and a conserved putative glycan binding site as that of P[14] VP8*. This study provided further knowledge of the glycan binding and structural features of P[25] RV VP8*, promoting our understanding of the infection, prevalence, and host range of the P[III] RVs. • Determine the crystal structure of human P[25] RV VP8* and uncover the VP8* structural characteristics. • Confirm that human P[25] VP8* specifically interacted with A-type histo-blood group antigen. • P[25] VP8* was most close to P[14] VP8* and possessed basically the same residues and conformation as that in P[14] VP8*. • A-type histo-blood group antigen may play an important role in the RV prevalence and transmission. [ABSTRACT FROM AUTHOR]

A correction to the article "An Open Receptor-Binding Cavity of Hemagglutinin-Esterase-Fusion Glycoprotein from Newly-Identified Influenza D Virus: Basis for Its Broad Cell Tropism," that as published in the 2016 issue is presented.

SARS-CoV-2 variants with severe immune evasion are a major challenge for COVID-19 prevention, especially the circulating Omicron XBB/BQ.1.1/BF.7 strains. Thus, the next-generation of broad-spectrum vaccines are urgently needed. Previously, we developed a COVID-19 protein subunit vaccine, ZF2001, based on the RBD-homodimer as the immunogen. To adapt SARS-CoV-2 variants, we developed chimeric RBD-heterodimers to induce broad immune responses. In this study, we further explored the concept of tandem RBD homotrimer and heterotrimer. Prototype SARS-CoV-2 RBD-homotrimer, prototype-Delta-BA.1 (PDO) RBD-heterotrimer and Delta-BA.2-BA.5 (DBA2BA5) RBD-heterotrimer were designed. Biochemical and cryo-EM structural characterization demonstrated total epitope exposure of the RBD-trimers. In mouse experiments, PDO and DBA2BA5 elicited broad SARS-CoV-2 neutralization. Potent protection against SARS-CoV-2 variants was observed in challenge assays and was correlated with neutralizing antibody titer. This study validated the design strategy of tandem RBD-heterotrimers as multivalent immunogens and presented a promising vaccine candidate, DBA2BA5, eliciting broad-spectrum immune responses, including against the circulating XBB/BF.7/BQ.1.1. Author summary: SARS-CoV-2 variants continue to emerge and circulate. Omicron sub-variants show severe evasion of the immune response induced by early-approved vaccines. Bivalent mRNA vaccines (prototype and Omicron BA. 5) have been approved for use in the United States and other countries. However, the co-circulation of SARS-CoV-2 variants (such as BA. 5.2, BF. 7, BQ. 1.1 and XBB) poses a challenge to disease control. The next-generation of COVID-19 vaccines need to induce potent and broad-spectrum immune responses. Here, we demonstrate a design strategy for trivalent SARS-CoV-2 vaccines with RBD-heterotrimers, which are single protein molecules without any linker sequences or trimerization domain. Biochemical and cryo-EM structural characterization demonstrated the total epitope exposure of RBD-trimers. Animal experiments showed that RBD-heterotrimers induce broad-spectrum protective immune responses. As a proof-of-concept, this trivalent immunogen design strategy is promising and practical for preventing the continuous circulation of SARS-CoV-2. This study provides guidance for future vaccine design against coronavirus and other viruses such as the influenza and dengue viruses. [ABSTRACT FROM AUTHOR]

The role of nitric oxide (NO) in response to chilling stress in walnut ( Juglans regia L.) seedlings was investigated. Walnut shoots were treated in vitro with sodium nitroprusside (SNP), NO scavenger 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (PTIO), NO synthase (NOS) inhibitor N -nitro- L -Arg-methyl ester ( L -NAME), and nitrate reductase (NR) inhibitor sodium tungstate. Their effects on chilling tolerance, the contents of soluble sugar, proline, and total phenol, reduced glutathione (GSH) and redox state (GSH/GSSG), and the activities of NOS and NR and NO level were analyzed. The results showed that low temperatures at 4 °C induced electrolyte leakage, lipid peroxidation and photosynthetic efficiency suppression, which were dramatically alleviated by exogenous application of SNP. The levels of soluble sugar, proline, total phenol, GSH and GSH/GSSG increased evidently in the presence of SNP under chilling stress. The above protective effect of SNP could be reversed by NO scavenger PTIO or NOS inhibitor. However, NR inhibitors did not affect the protective effect of SNP. Moreover, measurements of NOS activity and NO production showed that both NOS activity and endogenous NO content increased markedly under chilling stress. The NO production was markedly reduced by NOS inhibitors, but not affected by NR inhibitors in the presence or absence of chilling stress. Taken together, these results suggest that NOS-dependent NO production may confer chilling tolerance in walnut shoots in vitro by enhancing the levels of soluble sugar, proline, total phenol, GSH and GSH/GSSG to alleviate electrolyte leakage, lipid peroxidation and photosynthetic efficiency suppression induced by chilling stress. [ABSTRACT FROM AUTHOR]

An early and yet indispensable step in the alphaherpesvirus infection is the engagement of host receptors by the viral envelope glycoprotein D (gD). Of the thus-far identified gD receptors, nectin-1 is likely the most effective in terms of its wide usage by multiple alphaherpesviruses for cell entry. The molecular basis of nectin-1 recognition by the gD protein is therefore an interesting scientific question in the alphaherpesvirus field. Previous studies focused on the herpes simplex virus (HSV) of the Simplexvirus genus, for which both the free gD structure and the gD/nectin-1 complex structure were reported at high resolutions. The structural and functional features of other alphaherpesviral gDs, however, remain poorly characterized. In the current study, we systematically studied the characteristics of nectin-1 binding by the gD of a Varicellovirus genus member, the pseudorabies virus (PRV). We first showed that PRV infects host cells via both human and swine nectin-1, and that its gD exhibits similar binding affinities for nectin-1 of the two species. Furthermore, we demonstrated that removal of the PRV gD membrane-proximal residues could significantly increase its affinity for the receptor binding. The structures of PRV gD in the free and the nectin-1-bound states were then solved, revealing a similar overall 3D fold as well as a homologous nectin-1 binding mode to its HSV counterpart. However, several unique features were observed at the binding interface of PRV gD, enabling the viral ligand to utilize different gD residues (from those of HSV) for nectin-1 engagement. These observed binding characteristics were further verified by the mutagenesis study using the key-residue mutants of nectin-1. The structural and functional data obtained in this study, therefore, provide the basis of receptor recognition by PRV gD. [ABSTRACT FROM AUTHOR]

The line of balance method that provides continuous and uninterrupted use of resources is one of the best methods for repetitive project resource management. This paper develops a resource leveling algorithm based on the backward controlling activity in line of balance. The backward controlling activity is a kind of special activity, and if its duration is prolonged the project duration could be reduced. It brings two advantages to the resource leveling: both the resource allocated on the backward activity and the project duration are reduced. A resource leveling algorithm is presented which permits the number of crews of the backward controlling activity to be reduced until the terminal situation is reached, where the backward controlling activity does not exist or the number of crews cannot be reduced. That adjustment enables the productivity of all activities to be consistent. An illustrative pipeline project demonstrates the improvement in resource leveling. And this study designed a MATLAB program to execute the design algorithm. The proposed model could help practitioners to achieve the goals of both resource leveling and project duration reduction without increasing any resource. [ABSTRACT FROM AUTHOR]

Bat‐origin RshSTT182 and RshSTT200 coronaviruses (CoV) from Rhinolophus shameli in Southeast Asia (Cambodia) share 92.6% whole‐genome identity with SARS‐CoV‐2 and show identical receptor‐binding domains (RBDs). In this study, we determined the structure of the RshSTT182/200 receptor binding domain (RBD) in complex with human angiotensin‐converting enzyme 2 (hACE2) and identified the key residues that influence receptor binding. The binding of the RshSTT182/200 RBD to ACE2 orthologs from 39 animal species, including 18 bat species, was used to evaluate its host range. The RshSTT182/200 RBD broadly recognized 21 of 39 ACE2 orthologs, although its binding affinities for the orthologs were weaker than those of the RBD of SARS‐CoV‐2. Furthermore, RshSTT182 pseudovirus could utilize human, fox, and Rhinolophus affinis ACE2 receptors for cell entry. Moreover, we found that SARS‐CoV‐2 induces cross‐neutralizing antibodies against RshSTT182 pseudovirus. Taken together, these findings indicate that RshSTT182/200 can potentially infect susceptible animals, but requires further evolution to obtain strong interspecies transmission abilities like SARS‐CoV‐2. Synopsis: Bat‐origin coronaviruses RshSTT182 and RshSTT200 share 92.6% genome identity with SARS‐CoV‐2. The structure of the RshSTT182/200 spike protein RBD in complex with human ACE2 and analysis of its ACE2 receptor‐binding spectra indicate that while RshSTTT182/200 has a broad host range, it is narrower than that of SARS‐CoV‐2. The binding affinity of the RshSTT182/200 RBD to hACE2 was ~3 orders of magnitude lower than that of the SARS‐CoV‐2 RBD.RshSTT182‐pseudotyped viruses are able to enter hACE2‐expressing cells at low levels.The structure of the RshSTT182/200 RBD in complex with hACE2 reveals key residues involved in receptor binding.Bat‐origin RshSTT182/200 display a broad host range but show lower receptor‐binding affinity than SARS‐CoV‐2.SARS‐CoV‐2‐induced antibodies can cross‐neutralize RshSTT182. [ABSTRACT FROM AUTHOR]

Foot-and-mouth disease virus (FMDV) poses a significant threat to the livestock industry. Through their recognition of the conserved epitopes presented by the swine leukocyte antigen (SLA), T cells play a pivotal role in the antiviral immunity of pigs. Herein, based on the peptide binding motif of SLA-2*HB01, from an original SLA-2 allele, a series of functional T-cell epitopes derived from the dominant antigen VP1 of FMDV with high binding capacity to SLA-2 were identified. Two parallel peptides, Hu64 and As64, from the O and Asia I serotypes, respectively, were both crystallized with SLA-2*HB01. Compared to SLA-1 and SLA-3, the SLA-2 structures showed the flexibility of residues in the P4, P6, and P8 positions and in their potential interface with TCR. Notably, the peptides Hu64 and As64 adopted quite similar overall conformation when bound to SLA-2*HB01. Hu64 has two different conformations, a more stable 'chair' conformation and an unstable 'boat' conformation observed in the two molecules of one asymmetric unit, whereas only a single 'chair' conformation was observed for As64. Both Hu64 and As64 could induce similar dominant T-cell activities. Our interdisciplinary study establishes a basis for the in-depth interpretation of the peptide presentation of SLA-I, which can be used toward the development of universal vaccines. [ABSTRACT FROM AUTHOR]

The association of Zika virus ( ZIKV) infections with microcephaly and neurological diseases has highlighted an emerging public health concern. Here, we report the crystal structure of the full-length ZIKV nonstructural protein 1 ( NS1), a major host-interaction molecule that functions in flaviviral replication, pathogenesis, and immune evasion. Of note, a long intertwined loop is observed in the wing domain of ZIKV NS1, and forms a hydrophobic 'spike', which can contribute to cellular membrane association. For different flaviviruses, the amino acid sequences of the 'spike' are variable but their common characteristic is either hydrophobic or positively charged, which is a beneficial feature for membrane binding. Comparative studies with West Nile and Dengue virus NS1 structures reveal conserved features, but diversified electrostatic characteristics on both inner and outer faces. Our results suggest different mechanisms of flavivirus pathogenesis and should be considered during the development of diagnostic tools. [ABSTRACT FROM AUTHOR]

Antibody-mediated humoral immunity plays a pivotal role in flavivirus control. Neutralizing antibodies targeting viral envelope (E) protein, provide protection against flaviviruses in vivo but can also promote virus infection by antibody-dependent enhancement when antibodies are weakly neutralizing or in subneutralizing concentrations. The molecular basis for antibody-mediated virus neutralization can be revealed by structural studies of monoclonal antibodies complexed with the E protein or virion. In addition, the flavivirus non-structural protein NS1 can also induce host antibody production, and some of these antibodies can provide protection against virus challenge. In this review, we summarize the known structures of flavivirus neutralizing or protective antibodies bound to their epitopes and describe the underlying molecular mechanisms. © 2016 IUBMB Life, 68(10):783-791, 2016 [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has an extremely broad host range that includes hippopotami, which are phylogenetically closely related to whales. The cellular ACE2 receptor is one of the key determinants of the host range. Here, we found that ACE2s from several marine mammals and hippopotami could efficiently bind to the receptor-binding domain (RBD) of both SARS-CoV and SARS-CoV-2 and facilitate the transduction of SARS-CoV and SARS-CoV-2 pseudoviruses into ACE2-expressing cells. We further resolved the cryo-electron microscopy complex structures of the minke whale ACE2 and sea lion ACE2, respectively, bound to the RBDs, revealing that they have similar binding modes to human ACE2 when it comes to the SARS-CoV-2 RBD and SARS-CoV RBD. Our results indicate that marine mammals could potentially be new victims or virus carriers of SARS-CoV-2, which deserves further careful investigation and study. It will provide an early warning for the prospective monitoring of marine mammals. [ABSTRACT FROM AUTHOR]

In DFT watermarking algorithms, the watermarksare often embedded directly in the transformation coefficients, causing large errors in watermarked data. To overcome such disadvantage of these algorithms, a blind watermarking algorithm for copyright protection of vector geospatial data based on error reduction is proposed. This algorithm amplifies the DFT transform coefficients and embeds the watermarks in the amplitude coefficients and phase coefficients by DFT transform, and the watermark is embedded several times. In addition, the voting principle is utilized to detect the watermark. No original data is needed in the watermark extraction procedure. The experiments have shown that spatial accuracy of the watermarked data is acceptable and the algorithm is robust to a variety of geometric transformation attacks. [ABSTRACT FROM AUTHOR]

The recently emerged BA.2.86, JN.1, EG.5, EG.5.1, and HV.1 variants have a growth advantage. In this study, we explore the structural bases of receptor binding and immune evasion for the Omicron BA.2.86, JN.1, EG.5, EG.5.1, and HV.1 sub-variants. Our findings reveal that BA.2.86 exhibits strong receptor binding, whereas its JN.1 sub-lineage displays a decreased binding affinity to human ACE2 (hACE2). Through complex structure analyses, we observed that the reversion of R493Q in BA.2.86 receptor binding domain (RBD) plays a facilitating role in receptor binding, while the L455S substitution in JN.1 RBD restores optimal affinity. Furthermore, the structure of monoclonal antibody (mAb) S309 complexed with BA.2.86 RBD highlights the importance of the K356T mutation, which brings a new N-glycosylation motif, altering the binding pattern of mAbs belonging to RBD-5 represented by S309. These findings emphasize the importance of closely monitoring BA.2.86 and its sub-lineages to prevent another wave of SARS-CoV-2 infections. [Display omitted] • BA.2.86, JN.1, EG.5, EG.5.1, and HV.1 apo S structures and their hACE2 bound structures • An additional N-glycosylation of BA.2.86 RBD influences its binding to mAb S309 • Electrostatic changes in BA.2.86 contribute to immune evasion • JN.1 RBD L455S mutation maintains optimal receptor binding and enhances immune evasion Li et al. present the spike structures of the recently emerged BA.2.86, JN.1, EG.5, EG.5.1, and HV.1 SARS-CoV-2 variants and systematically analyzed these sub-variants. Compared to their ancestor BA.2, large scale of electrostatic changes were observed in the BA.2.86 and JN.1 RBDs, and the K356T mutation yields a novel N-glycosylation motif. [ABSTRACT FROM AUTHOR]

Nectin and nectin-like (Necl) co-receptor axis, comprised of receptors DNAM-1, TIGIT, CD96, PVRIG, and nectin/Necl ligands, is gaining prominence in immuno-oncology. Within this axis, the inhibitory receptor PVRIG recognizes Nectin-2 with high affinity, but the underlying molecular basis remains unknown. By determining the crystal structure of PVRIG in complex with Nectin-2, we identified a unique CC' loop in PVRIG, which complements the double-lock-and-key binding mode and contributes to its high affinity for Nectin-2. The association of the corresponding charged residues in the F-strands explains the ligand selectivity of PVRIG toward Nectin-2 but not for Necl-5. Moreover, comprehensive comparisons of the binding capacities between co-receptors and ligands provide innovative insights into the intra-axis immunoregulatory mechanism. Taken together, these findings broaden our understanding of immune recognition and regulation mediated by nectin/Necl co-receptors and provide a rationale for the development of immunotherapeutic strategies targeting the nectin/Necl axis. [Display omitted] • A unique CC' loop in PVRIG complements the double-lock-and-key binding mode to Nectin-2 • The PVRIG CC' loop contributes to high affinity binding of Nectin-2 • Charged residues central to the binding interface contribute to ligand selectivity • Comprehensive analysis of the interactions within the nectin/Necl co-receptor axis Hu et al. determined the crystal structure of the immune receptor PVRIG bound to Nectin-2. These findings contribute to a better understanding of immune recognition and immunoregulation within nectin/Necl co-receptor axis and provide the structural basis for further therapeutic development and target selection in immune checkpoint therapies. [ABSTRACT FROM AUTHOR]

The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway functions as a central hub for transmitting signals from more than 50 cytokines, playing a pivotal role in maintaining hematopoiesis, immune balance, and tissue homeostasis. Dysregulation of this pathway has been implicated in various diseases, including immunodeficiency, autoimmune conditions, hematological disorders, and certain cancers. Proteins within this pathway have emerged as effective therapeutic targets for managing these conditions, with various approaches developed to modulate key nodes in the signaling process, spanning from receptor engagement to transcription factor activation. Following the success of JAK inhibitors such as tofacitinib for RA treatment and ruxolitinib for managing primary myelofibrosis, the pharmaceutical industry has obtained approvals for over 10 small molecule drugs targeting the JAK-STAT pathway and many more are at various stages of clinical trials. In this review, we consolidate key strategies employed in drug discovery efforts targeting this pathway, with the aim of contributing to the collective understanding of small molecule interventions in the context of JAK-STAT signaling. We aspire that our endeavors will contribute to advancing the development of innovative and efficacious treatments for a range of diseases linked to this pathway dysregulation. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Nectin and nectin-like proteins are cell adhesion molecules that mediate the formation of cell adherens junctions by forming homo- or heterodimers. Some members of this protein family can also be used by immune receptors to mediate immune recognition. For instance, nectin-like 2 (Necl-2) is used as a ligand for the immune system by interaction with the immune receptor CRTAM (class-I MHC-restricted T cell associated molecule), which is mainly expressed on the surface of cytotoxic lymphocyte cells. However, the Necl-2/CRTAM binding mode and its relationship to cell adhesion are not known. Here, we report a Necl-2/CRTAM complex structure, demonstrating that Necl-2 binding to CRTAM competes with the dimerization of CRTAM and possibly Necl-2. Necl-2 occupies the CRTAM homodimer interface, making homodimerization impossible. Mutational and functional analyses identified key amino acids (double “lock-and-key”) responsible for the binding. Our work illustrates how the cell adhesion molecule Necl-2 competitively binds the immune receptor CRTAM. [ABSTRACT FROM AUTHOR]

Measles virus is a major public health concern worldwide. Three measles virus cell receptors have been identified so far, and the structures of the first two in complex with measles virus hemagglutinin (MV-H) have been reported. Nectin-4 is the most recently identified receptor in epithelial cells, and its binding mode to MV-H remains elusive. In this study, we solved the structure of the membrane-distal domain of human nectin-4 in complex with MV-H. The structure shows that nectin-4 binds the MV-H ?4-?5 groove exclusively via its N-terminal IgV domain; the contact interface is dominated by hydrophobic interactions. The binding site in MV-H for nectin-4 also overlaps extensively with those of the other two receptors. Finally, a hydrophobic pocket centered in the ?4-?5 groove is involved in binding to all three identified measles virus receptors, representing a potential target for antiviral drugs. [ABSTRACT FROM AUTHOR]

Background. Severe acute respiratory syndrome coronavirus (SARS-CoV), which emerged with highly contagious and life-threatening characteristics in 2002, remains a potential risk for future outbreaks. Membrane (M) and envelope (E) proteins are major structural proteins of the SARS-CoV. The M protein has been determined as a protective antigen in humoral responses. However, its potential roles in stimulating cellular immunity remain elusive.Methods. In this study, a panel of peptides derived from M and E proteins were tested by in vitro refolding, T2 cell-binding assays, and responses stimulated by cytotoxic T-lymphocyte (CTL) epitopes in HLA-A2.1/Kb transgenic mice and human peripheral blood mononuclear cells (PBMCs).Results. A nonameric epitope Mn2 and a decameric epitope Md3 derived from the M protein were identified and used for the evaluation of M protein-specific immunity. Responses stimulated by M protein-specific CTL epitopes have been found in the PBMCs of donors who had recovered from SARS infection. Additionally, the transmembrane domain of the M protein may contain a T cell epitope cluster revealed by the immunogenic and structural analysis of a panel of truncated peptides overlapping with Mn2 and Md3.Conclusions. The M protein of SARS-CoV holds dominant cellular immunogenicity. This, together with previous reports of a strong humoral response against the M protein, may help to further explain the immunogenicity of SARS and serves as potential targets for SARS-CoV vaccine design. [ABSTRACT FROM PUBLISHER]

Phosphoribosylaminoimidazole-succinocarboxamide synthase (SAICAR synthase) plays an essential role in the de novo biosynthesis of purine nucleotides. In this study, the SAICAR synthase from Streptococcus suis was cloned and overexpressed in Escherichia coli. The subsequent product was purified and crystallized using the hanging-drop vapour-diffusion method. The crystals diffracted to 2.8 Å resolution and belonged to space group P2, with unit-cell parameters a = 70.2, b = 52.2, c = 153.9 Å, β = 102.8°. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome virus 2 (SARS-CoV-2) invades host cells by interacting with receptors/coreceptors, as well as with other cofactors, via its spike (S) protein that further mediates fusion between viral and cellular membranes. The host membrane protein, angiotensin-converting enzyme 2 (ACE2), is the major receptor for SARS-CoV-2 and is a crucial determinant for cross-species transmission. In addition, some auxiliary receptors and cofactors are also involved that expand the host/tissue tropism of SARS-CoV-2. After receptor engagement, specific proteases are required that cleave the S protein and trigger its fusogenic activity. Here we discuss the recent advances in understanding the molecular events during SARS-CoV-2 entry which will contribute to developing vaccines and therapeutics. Both severe acute respiratory syndrome virus 2 (SARS-CoV-2) and SARS-CoV mainly invade human lungs, although increasing evidence shows that SARS-CoV-2 can also infect many other tissues to develop systematic infection and multiple organ damage, and can also hijack T cells to directly paralyze host immunity. Angiotensin-converting enzyme 2 (ACE2) is the major receptor for SARS-CoV-2 infection and is a crucial determinant for cross-species transmission of the virus; SARS-CoV-2 can establish infections in a panel of domestic or wild animals via their ACE2 orthologs. Several proteins and non-protein molecules have been found to interact with SARS-CoV-2 S protein and serve as potential alternative/auxiliary attachment receptors/coreceptors to facilitate SARS-CoV-2 entry into specific types of host cells. Membrane fusion of SARS-CoV-2 requires two proteolytic events of S protein by host proteases, and the S1/S2 boundary of SARS-CoV-2 S protein harbors a polybasic insertion that expands the spectrum of available proteases and thus the tropism for different tissues. [ABSTRACT FROM AUTHOR]

This study characterized the effect of green manures (February orchid, hairy vetch, rattail fescue and a no-green-manure control) and the termination method (flail or disk) on nutrient contents, enzyme activities, microbial biomass, microbial community structure of rhizosphere soil and vegetative growth of walnut tree. All three selected green manures significantly enhanced the water content, organic C, total N and available P. The rattail fescue significantly decreased the mineral N. Total organic C, total N, mineral N and available P were significantly greater under flail than under disk. Hairy vetch and February orchid significantly improved levels of soil β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activity, whereas rattail fescue improved only β-glucosidase activity. All of the green manures significantly decreased phenoloxidase activity. β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activities were significantly greater under flail relative to disk. The termination method had no significant effect on phenoloxidase activity. The different types of green manures and termination methods significantly altered the soil microbial biomass and microbial community structure. The green-manure treatments were characterized by a significantly greater abundance of Gram-positive (Gram +) bacteria, total bacteria and saprophytic fungi compared to the control. Hairy vetch significantly decreased the abundance of arbuscular mycorrhizal fungi (AMF) while February orchid and rattail fescue increased their abundance compared to the no-green-manure treatment. The abundance rates of Gram+ bacteria, actinomycetes, saprophytic fungi and AMF were significantly greater in soils under flail than under disk. In terms of vegetative growth of walnut tree, hairy vetch showed the greatest positive effects. The growth of walnut tree was significantly greater under flail relative to disk. Our results indicate that green-manure application benefits the rhizosphere soil micro-ecology, rhizosphere soil nutrient contents and tree growth. Overall, the hairy vetch and flail combined treatment is recommended for walnut orchards in northern China. [ABSTRACT FROM AUTHOR]

Pangolins have been suggested as potential reservoir of zoonotic viruses, including SARS‐CoV‐2 causing the global COVID‐19 outbreak. Here, we study the binding of two SARS‐CoV‐2‐like viruses isolated from pangolins, GX/P2V/2017 and GD/1/2019, to human angiotensin‐converting enzyme 2 (hACE2), the receptor of SARS‐CoV‐2. We find that the spike protein receptor‐binding domain (RBD) of pangolin CoVs binds to hACE2 as efficiently as the SARS‐CoV‐2 RBD in vitro. Furthermore, incorporation of pangolin CoV RBDs allows entry of pseudotyped VSV particles into hACE2‐expressing cells. A screen for binding of pangolin CoV RBDs to ACE2 orthologs from various species suggests a broader host range than that of SARS‐CoV‐2. Additionally, cryo‐EM structures of GX/P2V/2017 and GD/1/2019 RBDs in complex with hACE2 show their molecular binding in modes similar to SARS‐CoV‐2 RBD. Introducing the Q498H substitution found in pangolin CoVs into the SARS‐CoV‐2 RBD expands its binding capacity to ACE2 homologs of mouse, rat, and European hedgehog. These findings suggest that these two pangolin CoVs may infect humans, highlighting the necessity of further surveillance of pangolin CoVs. SYNOPSIS: Pangolins have been suggested as potential reservoir of zoonotic viruses including SARS‐CoV‐2. This study shows that spike proteins of two pangolin‐origin coronaviruses (CoVs) also bind human SARS‐CoV‐2 receptor ACE2, with mutation in one key residue extending host range at the molecular level. Cryo‐EM structures of receptor‐binding domains (RBDs) from two pangolin CoVs in complex with hACE2 reveal a binding mode similar to SARS‐CoV‐2.Compared to SARS‐CoV‐2, pangolin CoV spike proteins exhibit a broader in vitro binding range to ACE2 from different species.Pseudotyped viruses incorporating spike protein from the two pangolin CoVs can infect hACE2‐expressing cells.Introducing the Q498H substitution found in pangolin CoVs into the SARS‐CoV‐2 RBD expands its binding capacity to ACE2 homologs of mouse, rat and European hedgehog. [ABSTRACT FROM AUTHOR]

The genome composition of a given avian influenza virus is the primary determinant of its potential for cross‐species transmission from birds to humans. Here, we introduce a viral genome‐based computational tool that can be used to evaluate the human infectivity of avian isolates of influenza A H7N9 viruses, which can enable prediction of the potential risk of these isolates infecting humans. This tool, which is based on a novel class weight‐biased logistic regression (CWBLR) algorithm, uses the sequences of the eight genome segments of an H7N9 strain as the input and gives the probability of this strain infecting humans (reflecting its human infectivity). We examined the replication efficiency and the pathogenicity of several H7N9 avian isolates that were predicted to have very low or high human infectivity by the CWBLR model in cell culture and in mice, and found that the strains with high predicted human infectivity replicated more efficiently in mammalian cells and were more infective in mice than those that were predicted to have low human infectivity. These results demonstrate that our CWBLR model can serve as a powerful tool for predicting the human infectivity and cross‐species transmission risks of H7N9 avian strains. [ABSTRACT FROM AUTHOR]

There are no approved flaviviral therapies and the development of vaccines against flaviruses has the potential of being undermined by antibody-dependent enhancement (ADE). The flavivirus nonstructural protein 1 (NS1) is a promising vaccine antigen with low ADE risk but has yet to be explored as a broad-spectrum therapeutic antibody target. Here, we provide the structural basis of NS1 antibody cross-reactivity through cocrystallization of the antibody 1G5.3 with NS1 proteins from dengue and Zika viruses. The 1G5.3 antibody blocks multi-flavivirus NS1-mediated cell permeability in disease-relevant cell lines, and therapeutic application of 1G5.3 reduces viremia and improves survival in dengue, Zika, and West Nile virus murine models. Finally, we demonstrate that 1G5.3 protection is independent of effector function, identifying the 1G5.3 epitope as a key site for broad-spectrum antiviral development. [ABSTRACT FROM AUTHOR]

Outer membrane protein A (OmpA) of enterohaemorrhagic Escherichia coli (EHEC) plays multiple roles in bacterial physiology and pathogenesis, such as mediation of bacterial conjunction, maintenance of cell shape, induction of adhesion of EHEC to host cells etc. Better understanding of the functions of OmpA will help in the control of EHEC infections. OmpA is composed of two domains: the N-terminal domain and the C-terminal domain. The N-terminal domain is a β-barrel structure and embeds in the outer membrane of the bacterium. The structure and function of the C-terminal domain of OmpA (OmpAC) remain elusive. In this study, recombinant OmpAC from EHEC was purified and crystallized and a diffraction data set was collected to 2.7 Å resolution. The crystals belonged to space group I4132, with unit-cell parameter a = 158.99 Å. The Matthews coefficient and solvent content were calculated to be 2.55 Å3 Da−1 and 51.77%, respectively, for two molecules in the asymmetric unit. [ABSTRACT FROM AUTHOR]

2-Keto-3-deoxy-6-phosphogluconate (KDPG) adolase from pathogenic Streptococcus suis serotype 2 was crystallized using the hanging-drop vapour-diffusion method at 291 K. X-ray diffraction data were collected to 2.8 Å resolution. The crystal belonged to space group R32, with unit-cell parameters a = b = 126.4, c = 415.9 Å, α = β = 90, γ = 120°. Assuming the presence of six molecules in the asymmetric unit gave a VM value of 2.32 Å3 Da−1 and a solvent content of 47.12%. [ABSTRACT FROM AUTHOR]

Hepatitis E virus (HEV) is a non-enveloped, globular particle that is responsible for acute hepatitis. HEV is classified into the Hepeviridae family and can be divided into four species (A-D). All HEV variants that infect humans are reported to belong to species A (HEV-A), except species C (HEV-C), which was reported to infect humans in December 2018. We determined the crystal structure of the HEV-C E2s domain at 1.8 Å resolution. It contains a classical 12-stranded β-sandwich motif and forms dimers by hydrogen bonding, though the amino acid residues that form hydrogen bonds are quite different from the residues of HEV-A. The HEV-C E2s domain shares the common groove region with other structurally related viruses, and some subtle differences in this region may be related to host adoption or antibody binding. Antibody binding experiments and structural analysis revealed that HEV-C E2s is able to bind to the previously reported broad-spectrum antibody 8G12 but not bind to the antibody 8C11. Meanwhile, the structure analysis shows that HEV-C E2s does not have the key sites for binding to host cells as displayed by HEV-A (Genotype 1) E2s. These structural and biological findings present important implications for understanding the molecular mechanisms of host recognition and entry of HEV-C, as well as provide clues to the development of therapeutic antibodies and vaccines against HEV-C infection. • Classical 12-stranded β-sandwich motif and forms dimers by hydrogen bonding. • HEV-C E2s bind to the antibody 8G12 but not bind to the antibody 8C11. • HEV-C E2s lack the key sites for binding to host cells as HEV-A E2s. [ABSTRACT FROM AUTHOR]

COVID‐19, caused by SARS‐CoV‐2, has resulted in severe and unprecedented economic and social disruptions in the world. Nucleocapsid (N) protein, which is the major structural component of the virion and is involved in viral replication, assembly and immune regulation, plays key roles in the viral life cycle. Here, we solved the crystal structures of the N‐ and C‐terminal domains (N‐NTD and N‐CTD) of SARS‐CoV‐2 N protein, at 1.8 and 1.5 Å resolution, respectively. Both structures show conserved features from other CoV N proteins. The binding sites targeted by small molecules against HCoV‐OC43 and MERS‐CoV, which inhibit viral infection by blocking the RNA‐binding activity or normal oligomerization of N protein, are relatively conserved in our structure, indicating N protein is a promising drug target. In addition, certain areas of N‐NTD and N‐CTD display distinct charge distribution patterns in SARS‐CoV‐2, which may alter the RNA‐binding modes. The specific antigenic characteristics are critical for developing specific immune‐based rapid diagnostic tests. Our structural information can aid in the discovery and development of antiviral inhibitors against SARS‐CoV‐2 in the future. Synopsis: SARS‐CoV‐2 has emerged as a major health concern, and nucleocapsid (N) is a potential target for the development of antivirals to block ribonucleoprotein assembly. Here, the high‐resolution crystal structures of the N‐ and C‐terminal domains of SARS‐CoV‐2 N protein are reported, which provide a basis for antiviral drug discovery. Structures of the N‐ and C‐terminal domains (N‐NTD and N‐CTD) of SARS‐CoV-2 N protein, at 1.8 and 1.5 Å resolution, respectively.Both N‐NTD and N‐CTD display both conserved and specific features patterns in SARS‐CoV-2.Identification of features on N‐NTD that lend to structure‐based drug discovery. [ABSTRACT FROM AUTHOR]

The peptide obtained from walnut protein enzymatic hydrolysate had high ACE inhibitory activity. Through centrifugation, ultrafiltration, gel chromatography and high performance liquid chromatography (HPLC), the walnut oligo-peptide, which was denoted as P4-c with high ACE inhibitory activity was obtained. Three novel ACE inhibitory peptides, GVVPHN, EHSLDPLK and KTLLNFGPN, were identified from P4-c by high-resolution ion mobility mass spectrometry (IM-MS). The three novel ACE inhibitory peptides possessed good ACE inhibitory activity and the fraction GVVPHN had high ACE inhibitory activity with 27.3 µmol L−1 of IC50. The molar percentage of hydrophobic amino acids in the peptide GVVPHN was 50% while the hydrophobic amino acid contents of EHSLDPLK and KTLLNFGPN were 37.5% and 44.4%, respectively, which indicates ACE inhibitory activities were hydrophobicity of amino acid-dependent. [ABSTRACT FROM AUTHOR]

Bats harbor many zoonotic viruses, including highly pathogenic viruses of humans and other mammals, but they are typically asymptomatic in bats. To further understand the antiviral immunity of bats, we screened and identified a series of bat major histocompatibility complex (MHC) I Ptal-N*01:01–binding peptides derived from four different bat-borne viruses, i.e., Hendra virus (HeV), Ebola virus (EBOV), Middle East respiratory syndrome coronavirus (MERS-CoV), and H17N10 influenza-like virus. The structures of Ptal-N*01:01 display unusual peptide presentation features in that the bat-specific 3–amino acid (aa) insertion enables the tight “surface anchoring” of the P1-Asp in pocket A of bat MHC I. As the classical primary anchoring positions, the B and F pockets of Ptal-N*01:01 also show unconventional conformations, which contribute to unusual peptide motifs and distinct peptide presentation. Notably, the features of bat MHC I may be shared by MHC I from various marsupials. Our study sheds light on bat adaptive immunity and may benefit future vaccine development against bat-borne viruses of high impact on humans. [ABSTRACT FROM AUTHOR]

• Crystal structure of HLA-B*4001 was determined. • The salt bridges in HLA-B*4001 and H-2Kd have different structural characteristics. • MHC I mutations that disrupt the salt bridge alleviate peptide binding. • Mutations of the salt bridge-forming residues may impact TCR recognition, directly or indirectly. The viral peptides presentation by major histocompatibility complex class I (MHC I) molecules play a pivotal role in T-cell recognition and the subsequent virus clearance. This process is delicately adjusted by the variant residues of MHC I, especially the residues in the peptide binding groove (PBG). In a series of MHC I molecules, a salt bridge is formed above the N-terminus of the peptides. However, the potential impact of the salt bridge on peptide binding and T-cell receptor (TCR) recognition of MHC I, as well as the corresponding molecular basis, are still largely unknown. Herein, we determined the structures of HLA-B*4001 and H-2Kd in which two different types of salt bridges (Arg62-Glu163 or Arg66-Glu163) across the PBG were observed. Although the two salt bridges led to different conformation shifts of both the MHC I α helix and the peptides, binding of the peptides with the salt bridge residues was relatively conserved. Furthermore, through a series of in vitro and in vivo investigations, we found that MHC I mutations that disrupt the salt bridge alleviate peptide binding and can weaken the TCR recognition of MHC I-peptide complexes. Our study may provide key references for understanding MHC I-restricted peptide recognition by T-cells. [ABSTRACT FROM AUTHOR]