ABSTRACT
Conformational changes in bacteriophage tail proteins after heating and ionic strength alteration leading to dissociation of tail sheath have been studied using protein fluorescence, differential scanning microcalorimetry and electron microscopy methods. Autonomous structural changes in tube-baseplate proteins have been revealed. They take place under the same conditions as those which release the bonds holding the sheath protein subunits to those of the tube in isolated sheathed tails. The conformational changes in the tube-baseplates are reversible similarly to the process of assembly and disassembly of the extended sheath. Morphological changes in the tube have been found at the temperature above the transition registered by protein fluorescence but not by calorimetry. This suggests that revealed spectral alterations reflect changes in quaternary structure of tail tube in particular.
Subject(s)
T-Phages/analysis , Viral Proteins/analysis , Calorimetry, Differential Scanning , Fluorescence , Microscopy, Electron , Protein Conformation , Temperature , Viral Tail ProteinsABSTRACT
Treating of the bacteriophage T4B with cetyltrimethylammonium bromide results in extension of long fibers and contraction of tail sheaths. The unreorganized hexagonal baseplate attachment to the distal end of the tail core remains intact. Such aberrantly contracted phages are shown to retain the ability to absorb on the bacterial surface. The absorption is inhibited by sucrose and does not require the presence of 1-tryptophan. The aberrantly contracted phages lose the infection ability.
Subject(s)
Cetrimonium Compounds/pharmacology , Quaternary Ammonium Compounds/pharmacology , T-Phages/physiology , Adsorption , Cetrimonium , Cytopathogenic Effect, Viral , T-Phages/drug effects , Tryptophan/pharmacologyABSTRACT
Heat-induced structural transitions of bacteriophage T4 ghosts have been studied using differential scanning microcalorimetry and electron microscopy. The tail reorganization process is not an exothermic one. It is shown to correlate well with a heat absorption peak at maximum of 70 degrees C, but the sheath contraction and the hexagon -to-star base-plate transition themselves appear to proceed without any significant changes in enthalpy.
