[Base plate as a logical controller, matching receptor and other functions of bacteriophage T4]. / Bazal'naia plastinka--logicheskii modul', soglasuiushchii retseptornye i ispolnitel'nye funktsii bakteriofaga T4.

It has been shown that the complex functioning of the baseplate of the bacteriophage T4 is based on the high level hierarchy in the structure organization and on the interaction of protein components forming the hub and the "channels" of short and long fibers. The presence of structure proteins with stabilizing and destabilizing functions has been revealed. It has been shown that the process of binding of long tail fibers with cell receptors is a cooperative process. In general the baseplate can be considered as a logic module providing the transition from the adsorbtion to the nonreversible reorganization in the bacteriophage functioning.

[Does taxis exist in bacterial viruses?]. / Sushchestvuet li taksis u bakterial'nykh virusov?

By way of example of interaction of T4 bacteriophage with E. coli bacterium the scenario of enhancement of sorption of phages on bacteria through the remote mechanism of their cyclic interaction has been considered. An enlargement of the typical phage size, when its fibrillae are opened, underlies this mechanism. Modification of the structure of phages also occurs through the medium by release of products of bacterial metabolism into it. Allied questions related to investigation of physicochemical and biological processes, which require to take into account "fluffing" of microparticles. The medium-induced change of volume of microparticles leads to spatial cooperative effects with non-linear dynamics. Such phenomena are possible in all diffusional processes in biology, chemistry and physics.

Structural changes in Escherichia coli membranes induced by bacteriophage T4 at different temperatures.

This paper presents some further evidence for our model of DNA translocation into Escherichia coli cells by bacteriophage T4 (see Tarahovsky, Y. S., Khusainov, A. A., Deev, A. A., Kim, Y. V. 1991. FEBS Lett. 289:18-22). When lowering the temperature, we succeeded in slowing down the infection process and in observing a few separate stages by electron microscopy. Also, potassium leakage at different temperatures was measured. At 0-6 degrees C the phage was found to be irreversibly adsorbed on the cell surface, its tail to be contracted, and the outer membrane to be invaginated. Membrane fusion and formation of broad intermembrane bridges with a hole for potassium leakage were shown to start above 7 degrees C. At about 17-20 degrees C the diameter of the bridge decreased considerably, which could correspond to the sealing of the membrane.

Lysis of Escherichia coli cells induced by bacteriophage T4.

Structural changes in the envelope of Escherichia coli cells accompanying their lysis from without by bacteriophage T4 have been studied. The hypothesis concerning the role of collapse of membrane potential and formation of periplasmic vesicles in the process of lysis from without has been advanced.

[From disorder to order using the example of the function of phage T4 baseplate]. / Ot besporiadka k uporiadochennosti: na primere funktsionirovaniia bazal'noi plastinki faga T4.

The structure of key elements of T4 baseplate distal part was investigated by electron microscopy and image processing. The functional aspects of interaction of distal part structures in cell infection process were discussed. According to the results obtained earlier the baseplate functioning was suggested to be like a synchronization process of the complex protein structure caused by variation of external factors.

The structural and functional organization of the baseplate distal part of T4 bacteriophage.

The structural organization of the baseplate distal part of bacteriophage T4 has been studied. The investigations resulted in revealing the functional role of gene products '11' and '12' in the course of baseplate reorganization and DNA injection. A new model of 'arrangement' of gp12 in the intact particle is suggested. A functional interrelationship between long fibers of the phage and the protein complex of baseplate distal part has been established.

Effect of thermoinduced changes in T4 bacteriophage structure on the process of molecular recognition of 'host' cells.

By means of high-precision acoustic measurements and by methods of fluorescent and electron microscopy, investigations have been performed of thermoinduced conformational changes in T4 bacteriophage and its thermolabile mutants altered in baseplate proteins (gene products 7, 8, 10). A relationship was found between the conformational changes in T4 bacteriophage structure in the temperature range of 33-45 degrees C and the efficiency of bacteriophage adsorption and the changes in the orientation of long tail fibers. The possibility of heat regulation of 'recognition' of 'host' cells by bacterial viruses is suggested.

[The role of temperature as a factor of structure and functional fit of a "prey" virus based on the example of phage T4]. / Rol' temperatury kak faktora strukturno-funktsional'noi podstroike "khishchnika k zhertve" na primere faga T4.

By means of high-precision acoustic measurements and by the methods of fluorescent and electron microscopy investigations were performed of thermoinduced conformational changes in T4 bacteriophage and its thermolabile mutants altered in baseplate proteins (gene products "7", "8", "10"). A relationship was found between the conformational changes in T4 bacteriophage structure in the temperature range of 33-45 degrees C and the efficiency of bacteriophage adsorption and changes in the orientation of long tail fibers. Possibility of heat regulation of "recognition" of "host" cells by bacterial viruses is suggested.

Membrane fusion during infection of Escherichia coli cells by phage T4.

Phage T4 infection of Escherichia coli was studied by thin-section and freeze-fracture electron microscopy. It was found that phage T4 induces the formation of a bridge between the outer and inner membranes of E. coli. A membrane fusion during the infection is suggested.

[Kinetic features of aberration occurrence in thermally-induced reorganization of T4 phage]. / Kineticheskie osobennosti vozniknoveniia aberrantnosti pri termoindutsirovannoi reorganizatsii faga T4.

The reorganization process of bacteriophage T4B in the course of heating at various rates was studied. Reduction of the heating rate from 1 to 8.10(-4) degree per min showed that the content of normally reorganized particles was increased.

The detection of temperature induced structural changes in T4B and T7 bacteriophages by means of high precision acoustic velocity measurements.

High precision measurements of the velocity of 7-7.5 MHz ultrasonic waves in suspensions of both T4B and T7 bacteriophages as a function of temperature revealed the presence of a distinct transition in the physiological range of 35-45 degrees C. Data from acoustic measurements, sedimentation analysis and electron microscopy enabled us to identify this transition as being caused by the protein component of the phage and not the DNA. This transition does not depend on the position of the long tail fibers and may be part of some normal physiological process within the bacteriophage which presumably enhances its recognition and attachment to its host cell.

[Model of reversible phage interaction with cell receptors]. / Model' obratimogo vzaimodeistviia faga s kletochnymi retseptorami.

A model of the bacteriophage behavior at the reversible adsorption stage was investigated. The ratio of concentration of long fibres bound with receptors on bacterial surface to the total concentration of the fibres was taken to be efficiency range of reversible adsorption. To determine this value the expressions for concentrations of all the intermediate forms of the long fibres binding were obtained. The relationship between reversible adsorption efficiency and concentrations of receptors with various values of corresponding constants was computed. The conditions providing different types of cooperativeness in the behavior of the baseplate elements in the process of reversible adsorption were analysed.