Article: Estimation of the evolutionary stability of the Influenza A virus: Prediction of variable regions in the domain structure of the M1 protein[show abstract] [hide abstract]
ABSTRACT: Influenza virus is a human pathogen that is responsible for several pandemics with high death rates. Two programs were written for the statistical analysis of the coding regions of genes from extensive samples of Influenza A virus. While inner viral proteins appeared to be evolutionarily stable, surface antigens and the NS1 nonstructural protein are highly variable. Using programs to predict the evolutionarily variable regions inside the M1 protein sequence it was shown that the N-domain is the most conserved domain while the M- and C-domains are the most variable. In addition, the C-domain was shown to be the most unfolded one, according to prediction by the DISOPRED algorithm and, thus, possesses the most structural plasticity.Moscow University Biological Sciences Bulletin 04/2012; 65(4):221-223.
Article: Nonequilibrium processes in reactions of hot tritium atoms with cooled solid targets. Influence of the atomizer temperature on formation of labeled substances[show abstract] [hide abstract]
ABSTRACT: A system consisting of a cold target and “hot” atoms generated by dissociation of tritium on a tungsten wire was studied with the aim to determine conditions for preparing tritium-labeled organic compounds with the maximal radiochemical yield. The influence of the atomizer temperature on the result of the reaction of tritium atoms with amino acids and tetraalkylammonium bromides was studied; homological series of the substrates were examined with the aim to evaluate the contributions of functional groups and hydrocarbon tail to the processes occurring in the target. The dependence of the yield of the labeled parent compound on the atomizer temperature varied in the range 1600–2000 K was determined. The rates of decarboxylation and deamination sharply grew with increasing temperature of the tungsten wire. The highest yield of labeled amino acids was attained at an atomizer temperature of 1800–1900 K, and at higher temperature their yield decreased. The difference between the activation energies of the elimination of the carboxy and amino groups and of the isotope exchange of hydrogen for tritium in the C-H bond appeared to be 93 and 59 kJ mol−1, respectively. For alkyltrimethylammonium bromides with the alkyl radicals C12H25, C14H29, and C16H33, the yield of the labeled parent compound reached 80–90% and was virtually independent of the atomizer temperature. The capability of tritium atoms to penetrate into the targets was evaluated. For the exponential model of the attenuation of the flow of tritium atoms inside the target, the attenuation factor for freeze-dried amino acids and alkyltrimethylammonium bromides as targets was 1.8 nm−1.Radiochemistry 04/2012; 49(2):186-189.
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ABSTRACT: The density of glycoprotein (GP) distribution on the virion surface substantially influences the virus infectivity and pathogenicity. A method to quantitatively determine the area occupied by surface GP spikes was proposed for influenza virus (Flu) strain A/PR/8/34 on the basis of data of tritium bombardment and dynamic light scattering. The latter was used to measure the diameter of intact virions and subviral particles (Flu virions lacking GP spikes after bromelain digestion). Intact virions and subviral particles were bombarded with a hot tritium atom flux, and the specific radioactivity of the matrix M1 protein was analyzed. The tritium label was incorporated into the amino acid residues of a thin exposed protein layer and partly penetrated through the lipid bilayer of the viral envelope, labeling M1, located under the lipid bilayer. The tritium label distribution among different amino acid residues was the same in M1 isolated from subviral particles and M1 isolated from intact virions, demonstrating that the M1 spatial structure remained unchanged during proteolysis of GP spikes. The difference in specific radioactivity between the M1 proteins isolated from intact virions and subviral particles was used to calculate the GP-free portion of the viral surface. Approximating the Flu virion as a sphere, the GP-covered area was estimated at 1.4 × 104 nm2, about 40% of the total virion surface. This was consistent with the cryoelectron tomography data published for Flu strain A/X-31. The approach can be applied for other enveloped high pathogenic viruses, such as HIV and the Ebola virus.Molecular Biology 11/2008; 42(6):973-975. · 0.66 Impact Factor
Article: Cold co-extraction of hemagglutinin and matrix M1 protein from influenza virus A by a combination of non-ionic detergents allows for visualization of the raft-like nature of the virus envelope.[show abstract] [hide abstract]
ABSTRACT: Membrane solubilization with a mixture of cold non-ionic detergents has been applied to isolate detergent-resistant membranes from intact virus A lipid bilayer. Association of the viral envelope glycoproteins and M1 into a raft lipid-protein complex was verified via detergent insolubility experiments, and the M1:HA stoichiometry of the proposed supramolecular complex was estimated via amino acid analysis. Electron microscopy and dynamic light scattering data revealed that these lipid-protein rafts form unilamellar vesicles with HA spikes on their surfaces similar to influenza virus virions. Together, our data suggest that the cold co-extraction technique visualizes the raft-like nature of the viral envelope and demonstrates the interaction of matrix M1 protein with the envelope.Archives of Virology 11/2008; 153(10):1977-80. · 2.11 Impact Factor
A. L. Ksenofontov, E. N. Dobrov, N. V. Fedorova, V. A. Radyukhin, G. A. Badun, A. M. Arutyunyan, E. N. Bogacheva, L. A. Baratova[show abstract] [hide abstract]
ABSTRACT: The M1 matrix protein of the influenza virus is one of the main structural components of the virion that performs several different functions in the infected cell. X-ray analysis (with 2.08 Å resolution) has been performed for the N-terminal part of the M1 protein (residues 2–158) but not for its C-terminal domain (159–252). In the present study, we analyzed the structure of the M1 protein of the influenza virus A/Puerto Rico/8/34 (H1N1) strain in acidic solution using tritium planigraphy. The incorporation of tritium label into the domains of the M1 protein were studied; the C domain and the interdomain loops are preferentially accessible to tritium. Analytical centrifugation and dynamic laser light scattering demonstrated anomalous hydrodynamic parameters and low structuredness of the M1 protein, which has also been confirmed by circular dichroism data. Bioinformatic analysis of the M1 protein sequence revealed intrinsically unstructured segments that were concentrated in the C domain and interdomain loops between the N-, M-, and C domains. We suggest that the multifunctionality of the M1 protein in a cell is determined by the plasticity of its tertiary structure, which is caused by the presence of intrinsically unstructured segments. Keywordsmatrix protein M1 of the influenza virus–3D structure–tritium bombardment–bioinformatic analysis–circular dichroismMolecular Biology 04/2012; 45(4):634-640. · 0.66 Impact Factor