High-resolution structural insights into the heliorhodopsin family.

Rhodopsins are the most abundant light-harvesting proteins. A new family of rhodopsins, heliorhodopsins (HeRs), has recently been discovered. Unlike in the known rhodopsins, in HeRs the N termini face the cytoplasm. The function of HeRs remains unknown. We present the structures of the bacterial HeR-48C12 in two states at the resolution of 1.5 Å, which highlight its remarkable difference from all known rhodopsins. The interior of HeR's extracellular part is completely hydrophobic, while the cytoplasmic part comprises a cavity (Schiff base cavity [SBC]) surrounded by charged amino acids and containing a cluster of water molecules, presumably being a primary proton acceptor from the Schiff base. At acidic pH, a planar triangular molecule (acetate) is present in the SBC. Structure-based bioinformatic analysis identified 10 subfamilies of HeRs, suggesting their diverse biological functions. The structures and available data suggest an enzymatic activity of HeR-48C12 subfamily and their possible involvement in fundamental redox biological processes.

ESR - a retinal protein with unusual properties from Exiguobacterium sibiricum.

This review covers the properties of a retinal protein (ESR) from the psychrotrophic bacterium Exiguobacterium sibiricum that functions as a light-driven proton pump. The presence of a lysine residue at the position corresponding to intramolecular proton donor for the Schiff base represents a unique structural feature of ESR. We have shown that Lys96 successfully facilitates delivery of protons from the cytoplasmic surface to the Schiff base, thus acting as a proton donor in ESR. Since proton uptake during the photocycle precedes Schiff base reprotonation, we conclude that this residue is initially in the uncharged state and acquires a proton for a short time after Schiff base deprotonation and M intermediate formation. Involvement of Lys as a proton donor distinguishes ESR from the related retinal proteins - bacteriorhodopsin (BR), proteorhodopsin (PR), and xanthorhodopsin (XR), in which the donor function is performed by residues with a carboxyl side chain. Like other eubacterial proton pumps (PR and XR), ESR contains a histidine residue interacting with the proton acceptor Asp85. In contrast to PR, this interaction leads to shift of the acceptor's pKa to more acidic pH, thus providing its ability to function over a wide pH range. The presence of a strong H-bond between Asp85 and His57, the structure of the proton-conducting pathways from cytoplasmic surface to the Schiff base and to extracellular surface, and other properties of ESR were demonstrated by solving its three-dimensional structure, which revealed several differences from known structures of BR and XR. The structure of ESR, its photocycle, and proton transfer reactions are discussed in comparison with homologous retinal proteins.

[Metal content of local foods in Pechenga district of Murmansk region].

Within international project KolArctic "Food safety and health in frontier area of Russia, Finland and Norway", the study covered local food sampling in Pechenga district of Murmansk region during autumn of 2013, including fish (from 6 lakes), game, mushrooms, wild and cultivated berries, vegetables from private gardens situated at various distances from Nickel and Zapolarnyi settlements, also polling among 400 residents. Levels of 13 metals in the foods were assessed in "Taifun" laboratory. MACs for cadmium was 1.5-2 times exceeded in mushrooms (lamellate and tubular), that for mercury was up to 3 times exceeded in aspen mushrooms. Fresh-water fish appeared to contain the highest levels of mercury, close to MAC. Assessing levels of other metals that were previously normalized in USSR, the findings are 1.5 times exceeded MAC for copper in milk mushrooms, MAC for nickel was 4.5 times exceeded in wild berries, 2.5 times exceeded in cultivated berries, 2 times exceeded in potatoes and 2.5 to 30 times exceeded in mushrooms. Mushrooms have to be considered as major sorbents of total complex of the metals under study. Fresh-water fish is foodstuff mostly contaminated with mercury. Highly toxic nickel has to be considered as a major factor of exposure (and health risk) among the population under study. The data obtained help to specify recommendations on restricting some food items and reducing health risk for the residents subjected to industrial releases from "Pechenganickel" enterprise.

High-resolution structure of a membrane protein transferred from amphipol to a lipidic mesophase.

Amphipols (APols) have become important tools for the stabilization, folding, and in vitro structural and functional studies of membrane proteins (MPs). Direct crystallization of MPs solubilized in APols would be of high importance for structural biology. However, despite considerable efforts, it is still not clear whether MP/APol complexes can form well-ordered crystals suitable for X-ray crystallography. In the present work, we show that an APol-trapped MP can be crystallized in meso. Bacteriorhodopsin (BR) trapped by APol A8-35 was mixed with a lipidic mesophase, and crystallization was induced by adding a precipitant. The crystals diffract beyond 2 Å. The structure of BR was solved to 2 Å and found to be indistinguishable from previous structures obtained after transfer from detergent solutions. We suggest the proposed protocol of in meso crystallization to be generally applicable to APol-trapped MPs.

[Evolutionary admonition: allergy].

The paper concerns phylogeny development of allergic reactivity, the most probable antecedents of allergic IgE antibodies, high affinity IgE receptor (Fc(epsilon)RI), presents comparative character of IgE - Fc(epsilon)RI and IgY- CHIR-AB1 interactions. The paper has given an insight of allergy as evolutionary selected reactivity for highly organized animals. This reactivity is directed to organization of allergen-specific inflammation and serves as biologically expedient, high-specific and high-sensitive reaction in response to allergen entering into the organism because of barrier tissue dysfunction. Such insight has raised a question on consequences of thoroughgoing allergy reactivity elimination for highly organized animals and their posterity.

Structural insights into light-driven anion pumping in cyanobacteria.

Transmembrane ion transport is a key process in living cells. Active transport of ions is carried out by various ion transporters including microbial rhodopsins (MRs). MRs perform diverse functions such as active and passive ion transport, photo-sensing, and others. In particular, MRs can pump various monovalent ions like Na+, K+, Cl-, I-, NO3-. The only characterized MR proposed to pump sulfate in addition to halides belongs to the cyanobacterium Synechocystis sp. PCC 7509 and is named Synechocystis halorhodopsin (SyHR). The structural study of SyHR may help to understand what makes an MR pump divalent ions. Here we present the crystal structure of SyHR in the ground state, the structure of its sulfate-bound form as well as two photoreaction intermediates, the K and O states. These data reveal the molecular origin of the unique properties of the protein (exceptionally strong chloride binding and proposed pumping of divalent anions) and sheds light on the mechanism of anion release and uptake in cyanobacterial halorhodopsins. The unique properties of SyHR highlight its potential as an optogenetics tool and may help engineer different types of anion pumps with applications in optogenetics.

Principal component analysis highlights the influence of temperature, curvature and cholesterol on conformational dynamics of lipids.

Membrane lipids are inherently highly dynamic molecules. Currently, it is difficult to probe the structures of individual lipids experimentally at the timescales corresponding to atomic motions, and consequently molecular dynamics simulations are used widely. In our previous work, we have introduced the principal component analysis (PCA) as a convenient framework for comprehensive quantitative description of lipid motions. Here, we present a newly developed open source script, PCAlipids, which automates the analysis and allows us to refine the approach and test its limitations. We use PCAlipids to determine the influence of temperature, cholesterol and curvature on individual lipids, and show that the most prominent lipid tail scissoring motion is strongly affected by these factors and allows tracking of phase transition. Addition of cholesterol affects the conformations and selectively changes the dynamics of lipid molecules, impacting the large-amplitude motions. Introduction of curvature biases the conformational ensembles towards more extended structures. We hope that the developed approach will be useful for understanding the molecular basis of different processes occurring in lipid membrane systems and will stimulate development of complementary experimental techniques probing the conformations of individual lipid molecules.

Unusual features of the c-ring of F1FO ATP synthases.

Membrane integral ATP synthases produce adenosine triphosphate, the universal "energy currency" of most organisms. However, important details of proton driven energy conversion are still unknown. We present the first high-resolution structure (2.3 Å) of the in meso crystallized c-ring of 14 subunits from spinach chloroplasts. The structure reveals molecular mechanisms of intersubunit contacts in the c14-ring, and it shows additional electron densities inside the c-ring which form circles parallel to the membrane plane. Similar densities were found in all known high-resolution structures of c-rings of F1FO ATP synthases from archaea and bacteria to eukaryotes. The densities might originate from isoprenoid quinones (such as coenzyme Q in mitochondria and plastoquinone in chloroplasts) that is consistent with differential UV-Vis spectroscopy of the c-ring samples, unusually large distance between polar/apolar interfaces inside the c-ring and universality among different species. Although additional experiments are required to verify this hypothesis, coenzyme Q and its analogues known as electron carriers of bioenergetic chains may be universal cofactors of ATP synthases, stabilizing c-ring and prevent ion leakage through it.

New Insights on Signal Propagation by Sensory Rhodopsin II/Transducer Complex.

The complex of two membrane proteins, sensory rhodopsin II (NpSRII) with its cognate transducer (NpHtrII), mediates negative phototaxis in halobacteria N. pharaonis. Upon light activation NpSRII triggers a signal transduction chain homologous to the two-component system in eubacterial chemotaxis. Here we report on crystal structures of the ground and active M-state of the complex in the space group I212121. We demonstrate that the relative orientation of symmetrical parts of the dimer is parallel ("U"-shaped) contrary to the gusset-like ("V"-shaped) form of the previously reported structures of the NpSRII/NpHtrII complex in the space group P21212, although the structures of the monomers taken individually are nearly the same. Computer modeling of the HAMP domain in the obtained "V"- and "U"-shaped structures revealed that only the "U"-shaped conformation allows for tight interactions of the receptor with the HAMP domain. This is in line with existing data and supports biological relevance of the "U" shape in the ground state. We suggest that the "V"-shaped structure may correspond to the active state of the complex and transition from the "U" to the "V"-shape of the receptor-transducer complex can be involved in signal transduction from the receptor to the signaling domain of NpHtrII.

[Molecular basis of allergy control].

The article describes the picture of the interaction between IgE and its high-affinity receptor (Fc(epsilon)RI) leading to cellular triggering and clinical manifestations of IgE-dependent allergy. New understanding of the key event of an allergic response has enabled new pharmacological interventions at this stage.

[The effect of structural-chemical characteristics of water-soluble polyelectrolyte complexes of ovalbumin on their immunological properties]. / O vliianii strukturno-khimicheskikh osobennostei vodorastvorimykh poliélektrolitnykh kompleksov oval'bumina na ikh immunologicheskie svoistva.

Immunogenicity of soluble protein antigens in the complexes with synthetic polyions may be regarded as depending both on the nature of polymer carrier and the structure of the protein-polyelectrolyte complex. The immunogenicity of stable soluble complexes of ovalbumin (OA) with polycation - quaternized poly-4-vinylpyridine (C-1) and copolymer of acrylic acid and 2-methyl-5-vinylpyridine (C-2) have been evaluated. Immunization of mice by C-1 have induced a vigorous formation of the anti-OA IgG antibodies and IgE homocytotropic antibodies, while immunogenicity of OA in C-2 was comparable with that of OA alone. The analysis of the structural-chemical features of the complexes investigated has shown that enhanced immunogenicity of C-1 may be due to (1) the non-homogeneous distribution of protein globulae among polycation macromolecules and to (2) the formation of complex with an asymmetrical structure, to (3) the high ability of C-1 to adsorb on a surface of the lymphoid cells and to induce a formation of intercellular aggregates. An enhancing of a stability and a size of C-2 in the presence of Cu2+ shows no influence on a immunogenicity of OA. An immunogenicity of both types of complexes does not depend upon the access of determinants of OA to antibodies so far as it has been shown that complex formation in both cases are not accompanied by an alteration of antigenicity and allergenicity of OA.

[A combination of kordaron with ritmilen: its effect on the electrophysiology of the heart and its clinical effectiveness]. / Kombinatsiia kordarona s ritmilinom: vliianie na élektrofiziologiiu serdtsa i klinicheskaia Teffektivnost'.

Combined effect of cordarone and ritmilen on myocardial electrophysiology was assessed in an acute medicated test, on the basis of electrophysiologic studies and transesophageal pacing test, in patients with resistant paroxysmal supraventricular tachycardia. The cordarone-ritmilen combination has proved efficient in 82.4% of cases and caused a significant change of the P-Q interval and effective refractory period (ERPav, ERPrv, ERPiv). The Q-T interval increased but never resulted in ventricular arrhythmias. Good antiarrhythmic effect was seen in 70.4% after 12 months. There were side effects in 10.7% of cases.

[Determination of ovalbumin-specific IgG antibodies in mouse sera by immunoenzyme analysis using horseradish peroxidase-conjugated staphylococcal protein A]. / Opredelenie spetsificheskikh IgG-antitel k oval'buminu v syvorotkakh myshei metodom immunofermentnogo analiza s ispol'zovaniem stafilokokkovogo proteina A, kon''iugirovannogo s peroksidazoi khrena.

The article deals with the possibility of using staphylococcal protein A conjugated with horse-radish peroxidase for the detection of specific IgG-antibodies to ovalbumin in mice by the indirect and competitive EIA techniques. Studies on specifying the parameters of the EIA system for the detection of specific IgG-antibodies are in progress.

[First experiences with the effect of low-energy electric impulse on the atrioventricular junction in various types of paroxysmal supraventricular tachycardia]. / Pervyi opyt nizkoénergeticheskogo élektroimpu'lsnogo vozdeistviia na atrioventrikuliarnoe soedinenie serdtsa pri nekotorykh paroksizma'lnykh nadzheludochkovykh takhikardiiakh.

Efficient treatment of paroxysmal supraventricular reciprocal tachycardias (nodal and orthodromal) was studied in 29 patients by applying low-energy discharges (mean 2.3 +/- 0.1 kV) to the area of the atrioventricular junction. Late results of the treatment were assessed 7-22 months later. Cessation of tachycardia paroxysms was observed in 10 patients, their lower frequency (by more than 50%) was seen in 14 cases. The value of discharge energy, their numbers, relations between potential amplitudes produced by atria and His' bundle, feasibility of paroxysm induction, presence or absence of bundle-branch block were not prognostic criteria for efficiency of this mode of therapy in the present investigation. In the authors' opinion, the method is promising in the treatment of atrioventricular nodal and orthodromal paroxysmal tachycardias.

[The therapeutic use of diucifon-activated immunocytes in adoptive transfer in mice with burn trauma complicated by Pseudomonas aeruginosa infection]. / Lechebnoe primenenie aktivirovannykh diutsifonom immunotsitov v usloviiakh adoptivnogo perenosa u myshei s ozhogovoi travmoi, oslozhnennoi sinegnoinoi infektsiei.

The effectiveness of the therapeutic use of diucyphone-stimulated syngeneic spleen cells was studied in mice with a burn trauma complicated by P. aeruginosa infection. For this purpose CBA mice were subjected to a burn of degree IIIa, covering 30% of their body surface, the wound was infected with P. aeruginosa strain, and 24 hours later spleen cells were taken from some of these animals. The spleen cells, incubated for 3 hours with or without diucyphone at a concentration of 10-100 micrograms/ml, were washed and reinfused intravenously to the remaining animals. The injection of diucyphone-treated spleen cells was shown to greatly increase the survival rate of the animals, to accelerate healing processes and to enhance the proliferative response of spleen cells to mitogens (phytohemagglutinin, concanavalin A) and interleukin-2. A conclusion was made on the efficacy of the therapeutic use of diucyphone-activated immunocompetent cells in cases of immunodeficiency induced by burn infection.

[Clinico-immunologic characteristics of acute toxic-allergic reactions to drugs and current methods for their treatment]. / Kliniko-immunologicheskaia kharakteristika ostrykh toksiko-allergicheskikh reaktsii na medikamenty i sovremennye metody ikh lecheniia.

The paper is concerned with clinicoimmunological and allergological characterization of 29 cases of acute toxic allergic reactions (ATAR) to drugs. Four degrees of severity of disease were identified; the most severe form was toxic epidermal necrolysis caused by the use of sulfanilamides and pyrazolones in patients with acute respiratory virus and bacterial infections. Blood analysis in patients with III-IV degree of severity showed a sharp decrease in Ctot and C3 up to 0, an increase in the level of circulating immunocomplexes and "average molecules". Cellular immunity in III degree of severity was decreased. The main principles of therapy using extracorporeal immunocorrective methods were worked out. A leukocyte natural migration inhibition test was used for specific diagnosis of intolerance to medication.

[Staged analysis of the lowered proliferative response of human lymphocytes to mitogens]. / Poétapnyi analiz snizhennogo proliferativnogo otveta limfotsitov cheloveka na mitogeny.

The current concepts of the mechanisms of initiation and regulation of the proliferative response of lymphoid cells underlie a series of research performed by the authors. Using the modern methods an attempt was made to analyze comprehensively the causes of its lowering in patients with congenital immune deficiency (ataxia-telangiectasia, the Louis-Bar syndrome). It was established that irresponsiveness of the patients' cells to mitogens is not associated with the inability of these cells to interact with mitogen, to produce the growth factor of T cells or adsorb it on their membrane. It is suggested that the derangement is likely to be connected with the blockade of the postmembrane component of the proliferation trigger. It is also assumed that the analysis of the low proliferative response employed by the authors can be successfully used for other pathologies.

[Comparative antihistamine and anti-allergic effects of various antihistamine preparations]. / Sravnitel'noe izuchenie antigistaminnoi i antiallergicheskoi aktivnosti nekotorykh protivogistaminnykh preparatov.

AIM: To compare antihistaminic and antiallergic activity of antihistaminic drugs of the latest generation (ebastin, cetirisine, fexofenadine, loratadine) and antihistaminic drugs of the first generation (clemastin) in the same patients with pollenosis. MATERIAL AND METHODS: Skin prick-titration with 10-dilution histamine and specific allergen, provocative nasal titration with 2-dilution histamine and allergen before and after a single intake of H1-antagonists were made in 30 patients in stable clinical remission of pollenosis during maximal antihistamine activity of the above drugs. RESULTS: Systemic administration of the known H1-antagonists suppresses histamine sensitivity of both skin and nasal mucosa in the same degree. Drugs with more potent antihistaminic activity (fexofenadin and cetirisin) inhibited allergen-induced reactions more effectively. The order of the tested drugs by suppression of allergen-provoked skin and nasal reactions (by lowering antiallergic activity) is the following: fexofenadin and cetirisin > ebastin and loratadin > clemastin. CONCLUSION: The above drugs of the latest generation seem to posses antiallergic activity not only due to antihistaminic effect but also due to other mechanisms. Different suppressive action of H1-antagonists reflects also individual sensitivity to different drugs. The factor of individual sensitivity of the patients to a pharmacological action of the drug may be crucial in the selection of the most effective medicine for each patient. This is confirmed by the data of individual sensitivity of the patient to antihistaminic and antiallergic action of H1-antagonists. The illustrated method may be helpful for individual selection of H1-antagonists for treatment of patients with allergic diseases.

[A shock reaction from insect bites in patients with urticaria pigmentosa]. / Shokovaia reaktsiia pri uzhalenii nasekomym u bol'nykh pigmentnoi krapivnitsei.

The examination of 11 urticaria pigmentosa (UP) patients included allergological history, skin prick, scarification tests and intracutaneous tests with noninfectious and bee poison allergens, total and specific serum IgE measurements, in vitro reaction of histamine release from peripheral blood basophils induced by bee poison. The response of mastocytosis patients to insect sting was characterized by a rapid (within 5 min) development of severe systemic reactions or shock. The skin reactions and serum antibodies to bee poison were not registered in 9 of 11 patients. They also had a negative reaction of allergen-specific histamine release from basophils. This gives evidence for nonimmunological, pseudoallergic mechanism of the shock reaction. The latter can be prevented by bee poison immunotherapy. IgE-antibody-mediated allergic reaction to bee sting could not be excluded in 2 patients. For them specific immunotherapy with bee poison, possibly with purified poison preparations containing the allergens alone, are indicated.