Effect of lipid composition on the "membrane response" induced by a fusion peptide.

To understand the initial stages of membrane destabilization induced by viral proteins, the factors important for binding of fusion peptides to cell membranes must be identified. In this study, effects of lipid composition on the mode of peptides' binding to membranes are explored via molecular dynamics (MD) simulations of the peptide E5, a water-soluble analogue of influenza hemagglutinin fusion peptide, in two full-atom hydrated lipid bilayers composed of dimyristoyl- and dipalmitoylphosphatidylcholine (DMPC and DPPC, respectively). The results show that, although the peptide has a common folding motif in both systems, it possesses different modes of binding.

Helix Interactions in Membranes: Lessons from Unrestrained Monte Carlo Simulations.

We describe one of the first attempts at unrestrained modeling of self-association of α-helices in implicit heterogeneous membrane-mimic media. The computational approach is based on the Monte Carlo conformational search for peptides in dihedral angles space. The membrane is approximated by an effective potential.

Genome-wide identification and mapping of variable sequences in the genomes of Burkholderia mallei and Burkholderia pseudomallei.

Burkholderia mallei and Burkholderia pseudomallei, closely related Gram-negative bacteria, are the causative agents of such serious infectious diseases of humans and animals as glanders and melioidosis, respectively. Despite numerous studies of these pathogens, the detailed mechanisms of their pathogenesis is still poorly understood. One of the serious obstacles to revealing factors responsible for pathogenicity lies in the considerable natural variability of B.

Localization of Poa semilatent virus cysteine-rich protein in peroxisomes is dispensable for its ability to suppress RNA silencing.

Subcellular localization of the Poa semilatent virus cysteine-rich gammab protein was studied by using different approaches. In infected tissue, gammab was detected mainly in the P30 fraction as monomers, dimers and oligomers. Green fluorescent protein-fused gammab was found to localize in punctate bodies in the cytoplasm.

Genome-wide comparison reveals great inter- and intraspecies variability in B. pseudomallei and B. mallei pathogens.

Burkholderia mallei and B. pseudomallei, closely related Gram-negative bacteria, are causative agents of serious infectious diseases of humans and animals: glanders and melioidosis, respectively. Despite numerous studies of these pathogens, the detailed mechanism of their pathogenesis is still unknown.

Peptides and proteins in membranes: what can we learn via computer simulations?

Membrane and membrane-active peptides and proteins play a crucial role in numerous cell processes, such as signaling, ion conductance, fusion, and others. Many of them act as highly specific and efficient drugs or drug targets, and, therefore, attract growing interest of medicinal chemists. Because of experimental difficulties with characterization of their spatial structure and mode of membrane binding, essential attention is given now to molecular modeling techniques.

Effect of cholinergic and adrenergic receptor blockade on arrhythmogenic activity of endothelin-1 during inhibition of nitric oxide synthesis in awake mice.

We studied the effects of blockade of nicotinic receptors in sympathetic and parasympathetic ganglia (hexamethonium), muscarinic receptors (atropine), and beta1-adrenoceptors (atenolol) on arrhythmogenic activity of endothelin-1 during inhibition of nitric oxide synthesis with Nomega-nitro-L-arginine in NMRI mice. Atropine reduced, while hexamethonium completely abolished the arrhythmogenic effect of endothelin-1 during nitric oxide synthase inhibition. Atenolol potentiated arrhythmogenic activity of Nomega-nitro-L-arginine, but endothelin-1 had no effect on the incidence of arrhythmias under these conditions.

Development of the force field parameters for phosphoimidazole and phosphohistidine.

Phosphorylation of histidine-containing proteins is a key step in the mechanism of many phosphate transfer enzymes (kinases, phosphatases) and is the first stage in a wide variety of signal transduction cascades in bacteria, yeast, higher plants, and mammals. Studies of structural and dynamical aspects of such enzymes in the phosphorylated intermediate states are important for understanding the intimate molecular mechanisms of their functioning. Such information may be obtained via molecular dynamics and/or docking simulations, but in this case appropriate force field parameters for phosphohistidine should be explicitly defined.

Molecular modelling of the nucleotide-binding domain of Wilson's disease protein: location of the ATP-binding site, domain dynamics and potential effects of the major disease mutations.

WNDP (Wilson's disease protein) is a copper-transporting ATPase that plays an essential role in human physiology. Mutations in WNDP result in copper accumulation in tissues and cause a severe hepato-neurological disorder known as Wilson's disease. Several mutations were surmised to affect the nucleotide binding and hydrolysis by WNDP; however, how the nucleotides bind to normal and mutated WNDP remains unknown.

Expression of type IV collagen by Lewis pulmonary carcinoma cells.

Study of the expression of type IV collagen by Lewis pulmonary carcinoma cells (PLMG-T, PLMG-M1, PLMG-M2) showed that these cells produce type IV collagen. The expression of type IV collagen in PLMG-T and PLMG-M2 cells approximately 2-fold surpassed that in PLMG-M1 cells. The number of active cells (synthesizing type IV collagen) in PLMG-M1 culture was 1.

Arrhythmogenic effects of endothelin-1 under conditions of NO-synthase blockade with L-NAME in NMRI mice.

Arrythmogenic effects of endothelin-1 were studied in NMRI mice under conditions of NO-synthase blockade with N omega-nitro-L-arginine methyl ester. Intravenous injection of endothelin-1 increased heart rate variability in awake mice. NO-synthase blockade potentiated the arrythmogenic effects of endothelin-1.

Effects of central endothelin-1 in normotensive and spontaneously hypertensive rats.

Changes in blood pressure and sympathetic nerve activity induced by local injection of endothelin-1 into the rostroventrolateral medulla were studied in narcotized stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive WKY rats. Endothelin-1 produced similar biphasic response in both rat strains: a transient increase in blood pressure and sympathetic nerve activity followed by progressive hypotension and bradycardia. Pretreatment with ETB-receptor antagonist BQ788 inhibited sympathetic activation induced by endothelin-1, while pretreatment with the ETA-receptor antagonist N-acetyl-[D-Trp16]-endothelin-1 abolished the subsequent hypotension.

Effect of beta-endorphin and beta-endorphin-like peptide immunorphin on the growth of human leukemic cells in vitro.

The influence of beta-endorphin and immunorphin on human leukemic cell growth in vitro was studied. It was shown that both peptides increase the growth of T-lymphoblastoid cells in a dose-dependent manner. The effect of these peptides on the 3H-thymidine incorporation into T-lymphoblastoid cell line Jurkat was not reversed by the antagonist of opioid receptor naloxone.

Immunodetection and fluorescent microscopy of transgenically expressed hordeivirus TGBp3 movement protein reveals its association with endoplasmic reticulum elements in close proximity to plasmodesmata.

The subcellular localization of the hydrophobic TGBp3 protein of Poa semilatent virus (PSLV, genus Hordeivirus) was studied in transgenic plants using fluorescent microscopy to detect green fluorescent protein (GFP)-tagged protein and immunodetection with monoclonal antibodies (mAbs) raised against the GFP-based fusion expressed in E. coli. In Western blot analysis, mAbs efficiently recognized the wild-type and GFP-fused PSLV TGBp3 proteins expressed in transgenic Nicotiana benthamiana, but failed to detect TGBp3 in hordeivirus-infected plants.

Dysfunctionality of a tobacco mosaic virus movement protein mutant mimicking threonine 104 phosphorylation.

Replication of tobacco mosaic virus (TMV) is connected with endoplasmic reticulum (ER)-associated membranes at early stages of infection. This study reports that TMV movement protein (MP)-specific protein kinases (PKs) associated with the ER of tobacco were capable of phosphorylating Thr(104) in TMV MP. The MP-specific PKs with apparent molecular masses of about 45-50 kDa and 38 kDa were revealed by gel PK assays.

Phenotypic characteristics of lewis lung carcinoma cells.

We studied adhesive properties and physiological activity in vivo of cells from Lewis lung carcinoma and its metastases. These cells differed in tumorogenic activity and metastatic potential in the syngeneic system. In vivo non-metastasizing cells are characterized by a lower content of surface lectins to tetrasaccharides SiaLex [Neu5Aca2-3Galb1-4(Fuca1-3) GlcNAcb] and SiaLea [Neu5Aca2-3Galb1-3(Fuca1-4)GlcNAcb] and trisaccharide HSO3Lex [HSO32-3Galb1-4(Fuca1-3)GlcNAcb] compared to cells forming metastases in the syngeneic system.

Recombinant human insulin IX. Investigation of factors, influencing the folding of fusion protein-S-sulfonates, biotechnological precursors of human insulin.

The peculiarities of molecular structures and the influence of reaction conditions on the folding efficiency of fusion proteins-biotechnological precursors of human insulin, expressed in Escherichia coli as inclusion bodies have been investigated. The fusion proteins contained proinsulin sequence with various leader peptides connected by an Arg residue to the insulin B-chain. The kind and the size of leader peptide do not have essential influence on folding efficiency.

Monte Carlo simulations of voltage-driven translocation of a signal sequence.

Transmembrane potentials play important but poorly understood roles in many biological processes, including signal sequence-mediated protein translocation across bacterial membranes. In this study we applied Monte Carlo techniques to simulate the way the potential acts on a signal sequence. The simulations demonstrate that in the absence of a potential the signal sequence prefers insertion in both helical hairpin and transmembrane alpha-helical conformations.

Effect of myelopeptide-2 on the development of spontaneous and urethane-induced tumors in mice.

We studied the effect of endogenous immunoregulatory myelopeptide-2 on the development of spontaneous and urethane-induced lung adenomas. Long-term treatment with myelopeptide-2 (25 injections) in parallel with urethane poisoning decreased animal mortality caused by this carcinogen. Short-term treatment with myelopeptide-2 decreased the number of spontaneous and urethane-induced lung tumors in mice.

Interaction of cardiotoxins with membranes: a molecular modeling study.

Incorporation of beta-sheet proteins into membrane is studied theoretically for the first time, and the results are validated by the direct experimental data. Using Monte Carlo simulations with implicit membrane, we explore spatial structure, energetics, polarity, and mode of insertion of two cardiotoxins with different membrane-destabilizing activity. Both proteins, classified as P- and S-type cardiotoxins, are found to retain the overall "three-finger" fold interacting with membrane core and lipid/water interface by the tips of the "fingers" (loops).

A cytochrome c mutant with high electron transfer and antioxidant activities but devoid of apoptogenic effect.

A cytochrome c mutant lacking apoptogenic function but competent in electron transfer and antioxidant activities has been constructed. To this end, mutant species of horse and yeast cytochromes c with substitutions in the N-terminal alpha-helix or position 72 were obtained. It was found that yeast cytochrome c was much less effective than the horse protein in activating respiration of rat liver mitoplasts deficient in endogenous cytochrome c as well as in inhibition of H(2)O(2) production by the initial segment of the respiratory chain of intact rat heart mitochondria.

Role of the rostroventrolateral medulla in moxonidine-induced changes in cardiochronotropic regulation.

The cardiac component of baroreflex and sympathetic tone of the heart were studied in SHR-SP rats receiving moxonidine intragastrically or into the rostroventrolateral medulla. Moxonidine administered intragastrically in a dose of 10 mg/kg had no effect on cardiac sympathetic tone, but reduced the intracardiac rhythm and enhanced baroreflex bradycardia. Local injection of moxonidine into the rostroventrolateral medulla decreased cardiac sympathetic tone, but did not change the amplitude of baroreflex chronotropic responses.

Methods for preparation of recombinant cytokine proteins V. mutant analogues of human interferon-gamma with higher stability and activity.

Mutant analogues of recombinant human immune interferon (IFN-gamma) with higher stability and biological activity were prepared. Depending on the analogue, protein structure modification might involve introduction of an intramonomer disulfide bond (through replacements of Glu7Cys and Ser69Cys), C-terminal shortening by 10 amino acid residues, as well as Gln133Leu substitution in truncated variant. Isolation, purification, and renaturation of the IFN-gamma analogues expressed in Escherichia coli as inclusion bodies were performed according to the scheme developed earlier for wild-type protein.

The domain organization and properties of individual domains of DNA topoisomerase V, a type 1B topoisomerase with DNA repair activities.

Topoisomerase V (Topo V) is a type IB (eukaryotic-like) DNA topoisomerase. It was discovered in the hyperthermophilic prokaryote Methanopyrus kandleri and is the only topoisomerase with associated apurinic/apyrimidinic (AP) site-processing activities. The structure of Topo V in the free and DNA-bound states was probed by limited proteolysis at 37 degrees C and 80 degrees C.

New experimental model of multiple myeloma.

NSO/1 (P3x63Ay 8Ut) and SP20 myeloma cells were inoculated to BALB/c OlaHsd mice. NSO/1 cells allowed adequate stage-by-stage monitoring of tumor development. The adequacy of this model was confirmed in experiments with conventional cytostatics: prospidium and cytarabine caused necrosis of tumor cells and reduced animal mortality.