Differential effects of angiotensin II and aldosterone on human neutrophil adhesion and concomitant secretion of proteins, free amino acids and reactive oxygen and nitrogen species.

Invasion and adhesion of neutrophils into tissues and their concomitant secretion play an important role in the development of vascular pathologies, including abdominal aortic aneurysm (AAA). Chronic administration of angiotensin II is used to initiate AAA formation in mice. The role of aldosterone in this process is being studied.

Structural Insights into Plant Viruses Revealed by Small-Angle X-ray Scattering and Atomic Force Microscopy.

The structural study of plant viruses is of great importance to reduce the damage caused by these agricultural pathogens and to support their biotechnological applications. Nowadays, X-ray crystallography, NMR spectroscopy and cryo-electron microscopy are well accepted methods to obtain the 3D protein structure with the best resolution. However, for large and complex supramolecular structures such as plant viruses, especially flexible filamentous ones, there are a number of technical limitations to resolving their native structure in solution.

Peptide Models of the Cytoplasmic Tail of Influenza A/H1N1 Virus Hemagglutinin Expand Understanding its pH-Dependent Modes of Interaction with Matrix Protein M1.

Influenza A virus hemagglutinin (HA) is a major virus antigen. No cryo-electron microscopy or X-ray data can be obtained for the HA intraviral (cytoplasmic) domain (CT) post-translationally modified with long fatty acid residues bound to three highly conserved cysteines. We recently proposed a model of HA CT of Influenza A/H1N1 virus possessing an antiparallel beta structure based on the experimental secondary structure analysis of four 14-15 amino acid long synthetic peptides, corresponding to the HA CT sequence, with free or acetaminomethylated cysteines.

Structural and Immunoreactivity Properties of the SARS-CoV-2 Spike Protein upon the Development of an Inactivated Vaccine.

Inactivated vaccines are promising tools for tackling the COVID-19 pandemic. We applied several protocols for SARS-CoV-2 inactivation (by β-propiolactone, formaldehyde, and UV radiation) and examined the morphology of viral spikes, protein composition of the preparations, and their immunoreactivity in ELISA using two panels of sera collected from convalescents and people vaccinated by Sputnik V. Transmission electron microscopy (TEM) allowed us to distinguish wider flail-like spikes (supposedly the S-protein's pre-fusion conformation) from narrower needle-like ones (the post-fusion state).

The Mechanism of Selective Recognition of Lipid Substrate by hDHHC20 Enzyme.

S-acylation is a post-translational linkage of long chain fatty acids to cysteines, playing a key role in normal physiology and disease. In human cells, the reaction is catalyzed by a family of 23 membrane DHHC-acyltransferases (carrying an Asp-His-His-Cys catalytic motif) in two stages: (1) acyl-CoA-mediated autoacylation of the enzyme; and (2) further transfer of the acyl chain to a protein substrate. Despite the availability of a 3D-structure of human acyltransferase (hDHHC20), the molecular aspects of lipid selectivity of DHHC-acyltransferases remain unclear.

Molecular Dynamics of DHHC20 Acyltransferase Suggests Principles of Lipid and Protein Substrate Selectivity.

Lipid modification of viral proteins with fatty acids of different lengths (S-acylation) is crucial for virus pathogenesis. The reaction is catalyzed by members of the DHHC family and proceeds in two steps: the autoacylation is followed by the acyl chain transfer onto protein substrates. The crystal structure of human DHHC20 (hDHHC20), an enzyme involved in the acylation of S-protein of SARS-CoV-2, revealed that the acyl chain may be inserted into a hydrophobic cavity formed by four transmembrane (TM) α-helices.

Equilibrium Between Dimeric and Monomeric Forms of Human Epidermal Growth Factor is Shifted Towards Dimers in a Solution.

An interplay between monomeric and dimeric forms of human epidermal growth factor (EGF) affecting its interaction with EGF receptor (EGFR) is poorly understood. While EGF dimeric structure was resolved at pH 8.1, the possibility of EGF dimerization under physiological conditions is still unclear.

The Cytoplasmic Tail of Influenza A Virus Hemagglutinin and Membrane Lipid Composition Change the Mode of M1 Protein Association with the Lipid Bilayer.

Influenza A virus envelope contains lipid molecules of the host cell and three integral viral proteins: major hemagglutinin, neuraminidase, and minor M2 protein. Membrane-associated M1 matrix protein is thought to interact with the lipid bilayer and cytoplasmic domains of integral viral proteins to form infectious virus progeny. We used small-angle X-ray scattering (SAXS) and complementary techniques to analyze the interactions of different components of the viral envelope with M1 matrix protein.

COVID-19: Myths and Reality.

COVID-19, a new human respiratory disease that has killed nearly 3 million people in a year since the start of the pandemic, is a global public health challenge. Its infectious agent, SARS-CoV-2, differs from other coronaviruses in a number of structural features that make this virus more pathogenic and transmissible. In this review, we discuss some important characteristics of the main SARS-CoV-2 surface antigen, the spike (S) protein, such as (i) ability of the receptor-binding domain (RBD) to switch between the "standing-up" position (open pre-fusion conformation) for receptor binding and the "lying-down" position (closed pre-fusion conformation) for immune system evasion; (ii) advantage of a high binding affinity of the RBD open conformation to the human angiotensin-converting enzyme 2 (ACE2) receptor for efficient cell entry; and (iii) S protein preliminary activation by the intracellular furin-like proteases for facilitation of the virus spreading across different cell types.

The Structure of the Potato Virus A Particles Elucidated by Small Angle X-Ray Scattering and Complementary Techniques.

Potato virus A (PVA) protein coat contains on its surface partially unstructured N-terminal domain of the viral coat protein (CP), whose structural and functional characteristics are important for understanding the mechanism of plant infection with this virus. In this work, we investigated the properties and the structure of intact PVA and partially trypsinized PVAΔ32 virions using small-angle X-ray scattering (SAXS) and complimentary methods. It was shown that after the removal of 32 N-terminal amino acids of the CP, the virion did not disintegrate and remained compact, but the helical pitch of the CP packing changed.

NS1-mediated upregulation of ZDHHC22 acyltransferase in influenza a virus infected cells.

Influenza A viruses contain two S-acylated proteins, the ion channel M2 and the glycoprotein hemagglutinin (HA). Acylation of the latter is essential for virus replication. Here we analysed the expression of each of the 23 members of the family of ZDHHC acyltransferases in human airway cells, the site of virus replication.

Comparative Immunological Study in Mice of Inactivated Influenza Vaccines Used in the Russian Immunization Program.

A series of commercial inactivated influenza vaccines (IIVs) used in the Russian National Immunization Program were characterized to evaluate their protective properties on an animal model. Standard methods for quantifying immune response, such as hemagglutination inhibition (HAI) assay and virus neutralization (VN) assay, allowed us to distinguish the immunogenic effect of various IIVs from that of placebo. However, these standard approaches are not suitable to determine the role of various vaccine components in immune response maturation.

The cytoplasmic tail of influenza A/H1N1 virus hemagglutinin is β-structural.

Influenza A/H1N1 virus hemagglutinin (HA) is an integral type I glycoprotein that contains a large glycosylated ectodomain, a transmembrane domain, and a cytoplasmic tail (CT) of 10-14 amino acid residues. There are absolutely no data on the secondary or tertiary structure of the HA CT, which is important for virus pathogenesis. Three highly conserved cysteines are post-translationally modified by the attachment of fatty acid residues that pin the CT to the lipid membrane inside the virion.

Characterization of Inactivated Influenza Vaccines Used in the Russian National Immunization Program.

Background: today's standard quality control methods used to control the protein composition of inactivated influenza vaccines only take into account a few key reference components. They do not allow for thorough characterization of protein compositions. As a result, observation of unpredictable variations in major viral constituents and admixtures of cellular proteins within manufactured vaccines that may seriously influence the immunogenicity and safety of such vaccines has become a pressing issue in vaccinology.

Filamentous versus Spherical Morphology: A Case Study of the Recombinant A/WSN/33 (H1N1) Virus.

Influenza A virus is a serious human pathogen that assembles enveloped virions on the plasma membrane of the host cell. The pleiomorphic morphology of influenza A virus, represented by spherical, elongated, or filamentous particles, is important for the spread of the virus in nature. Using fixative protocols for sample preparation and negative staining electron microscopy, we found that the recombinant A/WSN/33 (H1N1) (rWSN) virus, a strain considered to be strictly spherical, may produce filamentous particles when amplified in the allantoic cavity of chicken embryos.

S-Acylation of Proteins.

Palmitoylation or S-acylation is the posttranslational attachment of fatty acids to cysteine residues and is common among integral and peripheral membrane proteins. Palmitoylated proteins have been found in every eukaryotic cell type examined (yeast, insect, and vertebrate cells), as well as in viruses grown in these cells. The exact functions of protein palmitoylation are not well understood.

Differential S-Acylation of Enveloped Viruses.

Post-translational modifications often regulate protein functioning. Covalent attachment of long chain fatty acids to cysteine residues via a thioester linkage (known as protein palmitoylation or S-acylation) affects protein trafficking, protein-protein and protein-membrane interactions. This post-translational modification is coupled to membrane fusion or virus assembly and may affect viral replication in vitro and thus also virus pathogenesis in vivo.

Matrix proteins of enveloped viruses: a case study of Influenza A virus M1 protein.

Influenza A virus, a member of the Orthomyxoviridae family of enveloped viruses, is one of the human and animal top killers, and its structure and components are therefore extensively studied during the last decades. The most abundant component, M1 matrix protein, forms a matrix layer (scaffold) under the viral lipid envelope, and the functional roles as well as structural peculiarities of the M1 protein are still under heavy debate. Despite multiple attempts of crystallization, no high resolution structure is available for the full length M1 of Influenza A virus.

The alpha helix 1 from the first conserved region of HIV1 gp120 is reconstructed in the short NQ21 peptide.

Investigations of short peptides that can be used in the next phase of synthetic HIV1 vaccine development are an urgent goal, as well as investigations of peptides that can be used in immunological tests with the aim to check the titer of antibodies against the alpha helix 1 from the first conserved region of HIV1 gp120 that are known to cause antibody-dependent cellular cytotoxicity (ADCC). The aim of this work was to study the structure of the NQ21 peptide corresponding to the less mutable part of the first conserved region of HIV1 gp120 (residues 94-114). The NQ21 peptide and its conjugate with biotin (biotin-NQ21) are absolutely alpha-helical in phosphate buffer solutions at pH = 6.

Structural and functional specificity of Influenza virus haemagglutinin and paramyxovirus fusion protein anchoring peptides.

Two enveloped virus families, Orthomyxoviridae and Paramyxoviridae, comprise a large number of dangerous pathogens that enter the host cell via fusion of their envelope with a target cell membrane at acidic or neutral pH. The Class I prototypic glycoproteins responsible for this reaction are the Influenza virus haemagglutinin (HA) protein or paramyxovirus fusion (F) protein. X-ray crystallography and cryoelectron microscopy data are available for the HA and F ectodomains in pre- and post-fusion conformations, revealing similar spiky architectures, albeit with clear differences in the details.

Site-specific S-acylation of influenza virus hemagglutinin: the location of the acylation site relative to the membrane border is the decisive factor for attachment of stearate.

S-Acylation of hemagglutinin (HA), the main glycoprotein of influenza viruses, is an essential modification required for virus replication. Using mass spectrometry, we have previously demonstrated specific attachment of acyl chains to individual acylation sites. Whereas the two cysteines in the cytoplasmic tail of HA contain only palmitate, stearate is exclusively attached to a cysteine positioned at the end of the transmembrane region (TMR).

Co-evolution analysis to predict protein-protein interactions within influenza virus envelope.

Interactions between integral membrane proteins hemagglutinin (HA), neuraminidase (NA), M2 and membrane-associated matrix protein M1 of influenza A virus are thought to be crucial for assembly of functionally competent virions. We hypothesized that the amino acid residues located at the interface of two different proteins are under physical constraints and thus probably co-evolve. To predict co-evolving residue pairs, the EvFold ( http://evfold.